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Previous studies suggested that degradation of contractile tissue requires cleavage of the costamere, a structural protein complex that holds sarcomeres in place. This study examined if costamere turnover is affected by a rotator cuff tear in a previously established ovine model. We found the activity of focal adhesion kinase (FAK), a main regulator of costamere turnover, was unchanged at 2 weeks but decreased by 27% 16 weeks after surgical release of the infraspinatus tendon. This was accompanied by cleavage of the costamere protein talin into a 190 kDa fragment while full length talin remained unchanged. At 2 weeks after tendon release, muscle volume decreased by 17 cm from an initial 185 cm(3) , the fatty tissue volume was halved, and the contractile tissue volume remained unchanged. After 16 weeks, the muscle volume decreased by 36 cm(3) , contractile tissue was quantitatively lost, and the fat content increased by 184%. Nandrolone administration mitigated the loss of contractile tissue by 26% and prevented fat accumulation, alterations in FAK activity, and talin cleavage. Taken together, these findings imply that muscle remodeling after tendon release occurs in two stages. The early decrease of muscle volume is associated with reduction of fat; while, the second stage is characterized by substantial loss of contractile tissue accompanied by massive fat accumulation. Regulation of costamere turnover is associated with the loss of contractile tissue and seems to be impacted by nandrolone treatment. Clinically, the costamere may represent a potential intervention target to mitigate muscle loss after a rotator cuff tear. © 2017 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res.

Background Open reduction and internal fixation (ORIF) of complex fractures of the proximal humerus may yield unsatisfactory results. This study analyzed the results obtained after revision of failed ORIF of proximal humeral fractures using reverse total shoulder arthroplasty (RTSA). Methods Fifty-four shoulders of 53 patients with a subjectively unacceptable outcome after ORIF of a complex fracture of the proximal humerus were revised with RTSA. At a minimum follow-up of 2 years (mean follow-up, 46 months; range, 24-108 months), 44 shoulders were clinically and radiographically reviewed for the purpose of this study. Six patients had been lost to follow-up, and 4 patients (7%) were excluded from functional analysis because of revision surgeries. Results The mean absolute Constant score improved from 26 (range, 4-54) to 55 (range, 19-80) points; the mean relative Constant score improved from 32% (range, 4%-85%) to 67% (range, 27%-94%) of an age- and gender-matched, normal shoulder. The mean subjective shoulder value improved from 29% (range, 0%-90%) preoperatively to 67% (range, 5%-95%) at final follow-up. Nineteen patients rated their outcome excellent, 16 good, and 7 fair; 2 patients were dissatisfied. Conclusion RTSA is a valuable salvage procedure after failed ORIF of a proximal humeral fracture with relatively low revision rates. Shoulder function, patient satisfaction, and pain levels can be reliably improved.

Achieving sufficient mechanical purchase of pedicle screws in osteoporotic or previously instrumented bone is technically and biologically challenging. Techniques using different kinds of pedicle screws or methods of cement augmentation have been used to address this challenge, but are associated with difficult revisions and complications. The purpose of this biomechanical trial was to investigate the use of biocompatible textile materials in combination with bone cement to augment pullout strength of pedicle screws while reducing the risk of cement extrusion. Pedicle screws (6/40mm) were either augmented with standard bone-cement (Palacos LV + G) in one group (BC, n = 13) or with bone-cement enforced by Vicryl mesh in another group (BCVM, n = 13) in osteoporosis-like saw bone blocks. Pullout testing was subsequently performed. In a second experimental phase, similar experiments were performed using human cadaveric lumbar vertebrae (n = 10). In osteoporosis-like saw bone blocks, a mean screw pullout force of 350N (± 125) was significantly higher with the Bone cement (BC) compared to bone-cement enforced by Vicryl mesh (BCVM) technique with 240N (± 64) (p = 0.030). In human cadaveric lumbar vertebrae the mean screw pullout force was 784 ± 366N with BC and not statistically different to BCVM with 757 ± 303N (p = 0.836). Importantly, cement extrusion was only observed in the BC group (40%) and never with the BCVM technique. In vitro textile reinforcement of bone cement for pedicle screw augmentation successfully reduced cement extrusion compared to conventionally delivered bone cement. The mechanical strength of textile delivered cement constructs was more reproducible than standard cementing. This article is protected by copyright. All rights reserved

The shape of the acromion differs between patients with degenerative rotator cuff tears and individuals without rotator cuff pathology. It can be assessed in the sagittal plane (acromion type, acromion slope) and in the coronal plane (lateral acromion angle, acromion index, critical shoulder angle). The inter-observer reliability is better for the measurements in the coronal plane. A large lateral extension (high acromion index or high critical shoulder angle) and a lateral down-sloping of the acromion (low lateral acromion angle) are associated with full-thickness supraspinatus tears. The significance of glenoid inclination for rotator cuff disease is less clear. The postulated patho-mechanism is the compression of the supraspinatus tendon between the humeral head and the acromion. Bursal side tears might be caused by friction and abrasion of the tendon. Articular side tears could be due to impairment of the gliding mechanism between tendon fibrils leading to local stress concentration. Further research is needed to understand the exact pathomechanism of tendon degeneration and tear. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160076. Originally published online at www.efortopenreviews.org

UBERBLICK: Das Schultergelenk ist das beweglichste Kugelgelenk im menschlichen Korper. Geht die erforderliche Stabilitat verloren, unterscheidet man aktuell drei grose Typen der Instabilitat: die statischen, die dynamischen und die willkurlichen. Unser Zuricher Autorenteam stellt sie vor und zeigt die jeweils geeigneten Therapiemoglichkeiten auf.

Achieving sufficient mechanical purchase of pedicle screws in osteoporotic or previously instrumented bone is technically and biologically challenging. Techniques using different kinds of pedicle screws or methods of cement augmentation have been used to address this challenge, but are associated with difficult revisions and complications. The purpose of this biomechanical trial was to investigate the use of biocompatible textile materials in combination with bone cement to augment pullout strength of pedicle screws while reducing the risk of cement extrusion. Pedicle screws (6/40 mm) were either augmented with standard bone-cement (Palacos LV + G) in one group (BC, n = 13) or with bone-cement enforced by Vicryl mesh in another group (BCVM, n = 13) in osteoporosis-like saw bone blocks. Pullout testing was subsequently performed. In a second experimental phase, similar experiments were performed using human cadaveric lumbar vertebrae (n = 10). In osteoporosis-like saw bone blocks, a mean screw pullout force of 350 N (±125) was significantly higher with the Bone cement (BC) compared to bone-cement enforced by Vicryl mesh (BCVM) technique with 240 N (±64) (p = 0.030). In human cadaveric lumbar vertebrae the mean screw pullout force was 784 ± 366 N with BC and not statistically different to BCVM with 757 ± 303 N (p = 0.836). Importantly, cement extrusion was only observed in the BC group (40%) and never with the BCVM technique. In vitro textile reinforcement of bone cement for pedicle screw augmentation successfully reduced cement extrusion compared to conventionally delivered bone cement. The mechanical strength of textile delivered cement constructs was more reproducible than standard cementing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:212-216, 2018.

Previous studies suggested that degradation of contractile tissue requires cleavage of the costamere, a structural protein complex that holds sarcomeres in place. This study examined if costamere turnover is affected by a rotator cuff tear in a previously established ovine model. We found the activity of focal adhesion kinase (FAK), a main regulator of costamere turnover, was unchanged at 2 weeks but decreased by 27% 16 weeks after surgical release of the infraspinatus tendon. This was accompanied by cleavage of the costamere protein talin into a 190 kDa fragment while full length talin remained unchanged. At 2 weeks after tendon release, muscle volume decreased by 17 cm3 from an initial 185 cm3, the fatty tissue volume was halved, and the contractile tissue volume remained unchanged. After 16 weeks, the muscle volume decreased by 36 cm3, contractile tissue was quantitatively lost, and the fat content increased by 184%. Nandrolone administration mitigated the loss of contractile tissue by 26% and prevented fat accumulation, alterations in FAK activity, and talin cleavage. Taken together, these findings imply that muscle remodeling after tendon release occurs in two stages. The early decrease of muscle volume is associated with reduction of fat; while, the second stage is characterized by substantial loss of contractile tissue accompanied by massive fat accumulation. Regulation of costamere turnover is associated with the loss of contractile tissue and seems to be impacted by nandrolone treatment. Clinically, the costamere may represent a potential intervention target to mitigate muscle loss after a rotator cuff tear. © 2017 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 36:272–281, 2018.

Objectives On standard axillary radiographs of normal shoulders, the clavicle may appear subluxated posteriorly. This subluxation might be viewed as an indication for surgical stabilization in acromioclavicular (AC) injury. The purpose of this study was to assess the reliability of identification of anteroposterior displacements of the AC joint on standard axillary radiographs of the human shoulder. Methods We performed 170 radiographs of the AC joint in 10 cadaveric shoulders using various projection angles. The distance from the anterior margin of the acromion to the distal clavicle was measured to identify an "optimal" view to image the true anteroposterior alignment of normal AC joints. Results On the standard axillary view of intact shoulders, we found an average posterior translation of 1.7 mm (range, -3 to 7; SD, 2.8) and of 0.9 mm (range, -5 to 5; SD, 2.8) in an "optimal view," tilted 15 degees dorsal and 15 degees lateral. Conclusions The standard axillary radiograph has a very high sensitivity but poor accuracy in identifying a posterior clavicular translation in the AC joint. We could not identify a reliable modification of the axillary radiographic projection to improve the accuracy. Therefore, an apparent posterior subluxation of the clavicle identified on an axillary radiograph is more likely a false positive finding than an identification of a true pathology.

Resume Les nœuds chirurgicaux sont particulierement sollicites par les sutures a haute resistance. Notre hypothese est que les sutures dans une configuration en boucle a double brin diminuent le nombre d’extremites de sutures libres a nouer et presentent des avantages mecaniques. Methodologie Cette etude biomecanique in vitro a teste 12 nœuds differents sur machine avec une vitesse de traction constante. Le nœud « cow hitch », sa version modifiee et les demi-cles conventionnelles ont egalement ete testes sur des tendons de bovin. Le materiau de suture est un polyester non resorbable tresse. L’interet principal est la securite du nœud (raideur) a la rupture (deplacement ≥ 3 mm). Les interets secondaires sont la taille du nœud et la securite de la boucle. Resultat Les nœuds en boucle a double brin sont jusqu’a trois fois plus resistants que les nœuds a un et demi et a simple brin. Le « cow hitch » est le plus rigide (moyenne 185 [IC a 95 % : 172–197] N/mm) (p Conclusion Les configurations de nœuds en boucle a double brin sont mecaniquement plus resistantes et plus rigides, moins volumineuses et conservent mieux la tension appliquee durant le nouage que les nœuds conventionnels. Les nœuds les plus performants et techniquement les plus simples qui conviennent le mieux pour exploiter les enormes capacites mecaniques des sutures a haute resistance sont le « cow hitch » et le nœud Nice. Niveau de preuve Non applicable du a la nature biomecanique de l’etude.

Purpose: High-strength sutures allow tightening of a suture knot beyond the strength of the surgeon, possibly inflicting skin damage through the gloves. This study was undertaken to evaluate whether such effort is useful and how much tensioning on a surgical knot is necessary. Methods: Three different suture materials were tested: No. 2 Vicryl™, FibreWire™, and PDS™. First, the force spontaneously applied on sutures during experimental knot tightening ("tying load”) was measured in fifteen experienced surgeons. Second, with each suture material, surgical square knots were tied with increasing, standardized loads (range 0.5-50N) using a custom-made apparatus. Thereby, knot seating after tying was evaluated, and by loading the knots to failure, evaluation for failure mode and failure load was performed. Results: FibreWire™ 5-throw square knots always failed by complete slipping of all knots (resolving), independent on the tying load. A nonlinear decrease of knot slippage and increased failure load were seen with increasing tying loads for all sutures. Major differences were seen between 0.5 and 10 N for FibreWire™ (slippage: 25mm) and PDS™ (99.6mm), whereas Vicryl™ showed major differences (22.7mm) between 0.5 and 2N. Increasing the tying load from 10 to 50N decreased the mean knot slippage from 12 (FibreWire™, ±2.6 SD), 9 (PDS™, ±1.8 SD) and 8 (Vicryl™, ±1.3 SD) mm to 6 (±2.9 SD), 3 (±1.5 SD) and 4mm (±0.9 SD), respectively. Conclusion: Slippage and self-seating of the knots under load is unavoidable even with highest tying loads. Relatively minor but possibly important differences can be seen for tying loads exceeding 2N (Vicryl™) and 10N (PDS™ and FibreWire™) for failure load and knot slippage. But also with a tying load of 50N, a minimal slippage of approximately 3mm seems unavoidable for all suture types. However, it is important to state that intense tightening does not prevent knot resolution and is only necessary in clinical situations that demand very tight sutures. Numbers and proper appliance of throws are more relevant than tying strength to reach the maximum failure load.

Anatomical reduction and fixation, early functional treatment, and prevention of posttraumatic osteoarthritis are the utmost goals in the treatment of articular fractures in the lower extremity. Especially in articular fractures of the ankle, where a high load transfer is omitted through a very smal

Background The source of pain in patellofemoral osteoarthritis is not fully understood. The purpose of this study was to identify the origin of pain using intraosseous pain catheters and to show early results with an osteotomy that is potentially denervating and hydrostatic pressure-relieving. Methods Five patients with patellofemoral osteoarthritis and pain with straight downward patellofemoral compression were included. All underwent arthroscopic placement of two 0.8mm catheters into the medial and lateral patella prior to subsequent patellar facetectomy with an incomplete horizontal patellar osteotomy. The catheters were first flushed with 0.5ml saline, then with local anaesthetic to determine pain response. After a mean of 44months the latest clinical examination was performed. Results Instillation of less than 0.5ml of saline provoked sharp pain, which could be localised by all patients as medial or lateral within the patella. Subsequent instillation of local anaesthetic suppressed the mean patellar tenderness during axial compression from VAS 6 to VAS 1. In one of the five patients, patellar osteotomy did not relieve symptoms and further surgical intervention was required. The remaining four patients experienced a clinical improvement with a mean subjective knee value of 55 (range 40 to 65) out of 100. Conclusion This is the first report on intraosseous catheters applying local anaesthetics into bone. There is a surprisingly precise intraosseous spatial resolution of pain perception in the patella and triggering of pain in osteoarthritis appears at least in part to occur through intraosseous increase of hydrostatic pressure. Level of Evidence: Level IV, Case Series.

Background Corrective osteotomies of malunited fractures of the proximal and distal humerus are among the most demanding orthopedic procedures. Whereas the restoration of the normal humeral anatomy is the ultimate goal, the quantification of the deformity as well as the transfer of the preoperative plan is challenging. The purpose of this study was to provide a guideline for 3-dimensional (3D) corrective osteotomies of malunited intra-articular fractures of the humerus and a detailed overview of existing and novel instruments to enlarge the toolkit for 3D preoperative planning and intraoperative realization using patient-specific guides. Methods We describe the preoperative 3D deformity analysis, relevant considerations for the preoperative plan, design of the patient-specific guides, and surgical technique of corrective osteotomies of the humerus. Results The presented technique demonstrates the benefit of computer-assisted surgery for complex osteotomies of the humerus from a preoperative deformity analysis to the creation of feasible surgical procedures and the generation of patient-specific guides. Conclusions A 3D analysis of a post-traumatic deformity of the humerus, 3D preoperative planning, and use of patient-specific guides facilitate corrective osteotomies of complex malunited humeral fractures.

Repetitive top-performance of overhead athletes induces a tremendous stress for the throwing shoulder. Throwers reach rotational speed of their arm of more than 7000°/s with joint compression and distraction forces of more than 1000 N. This performance is tributary to adaption of the shoulder muscles and the joint itself. These adaptions may, however lead to two specific problems of the throwing shoulder: 1. The posterosuperior internal impingement of the rotator cuff and labrum between glenoid and humeral head during late cooking phase; 2. A decreased internal rotation of the glenohumeral joint (GIRD) with compensatory problems of the scapula-stabilizing muscles. Precise analysis of kinematics and pathomechanics aims to improve understanding and treatment of those specific problems of the throwing shoulder.

Zusammenfassung. Repetitive sportliche Höchstleistungen der Überkopfsportler stellen eine enorme Belastung für das Schultergelenk dar. Werfer erlangen Wurfarmrotationsgeschwindigkeiten von über 7000°/s, wobei hierbei Gelenkskompressions- und Distraktionskräfte von über 1000 N entstehen. Dies ist nur durch eine Adaptation der Schultermuskulatur und des Schultergelenkes mit bis zu 29° vermehrter Humeruskopfretrotorsion möglich. Diese, bei Werfern besonders ausgeprägten Anpassungen, führen zu zwei typischen Problemen: 1. Das hintere Einklemmen der Rotatorenmanschette und des glenoidalen Labrums zwischen Gelenkspfanne und Humeruskopf («inneres Impingement») bei der Ausholbewegung; 2. Störende Innenrotationseinschränkung (GIRD) mit kompensatorischen Beschwerden der Scapula-stabilisierenden Muskulatur. Die präzise Analyse von Kinematik und Pathomechanik der Werferschulter hat zum Ziel, diese Überlastungsschäden zu verstehen und einer kausalen Therapie zuzuführen.

Elderly patients may be different from the average population in regard to the treatment of shoulder disorders. Challenges are the decreased quality of bone, tendons and cartilage, decreased blood perfusion and a generally aged biology. The advantages however are the often more realistic expectations and more cautious use of the extremity, and the limited life expectancy of prosthetic implants is a less pressing issue. Local pathologies such as in the AC-joint or long head of the biceps may also in the aged patient be treated with infiltration or arthroscopic means. If however large rotator cuff tears and osteoarthritis are present, (reverse) total shoulder implants are the treatment of choice due to the high reliability and uncomplicated rehabilitation.

The purposes of this study were (1) to establish a reproducible, standardized testing protocol to evaluate the performance of different shaver systems and blades in a controlled, laboratory setting, and (2) to determine the optimal use of different blades with respect to the influence of contact pressure and speed of blade rotation.A holding device was developed for reproducible testing of soft-tissue (tendon and meniscal) resection performance in a submerged environment, after loading of the shaver with interchangeable weights. The Karl Storz Powershaver S2 (Karl Storz, Tuttlingen, Germany), the Stryker Power Shaver System (Stryker, Kalamazoo, MI), and the Dyonics Power Shaver System (SmithNephew, Andover, MA) were tested, with different 5.5-mm shaver blades and varied contact pressure and rotation speed. For quality testing, serrated shaver blades were evaluated at 40× image magnification. Overall, more than 150 test cycles were performed.No significant differences could be detected between comparable blade types from different manufacturers. Shavers with a serrated inner blade and smooth outer blade performed significantly better than the standard smooth resectors (P.001). Teeth on the outer layer of the blade did not lead to any further improvement of resection (P = .482). Optimal contact pressure ranged between 6 and 8 N, and optimal speed was found to be 2,000 to 2,500 rpm. Minimal blunting of the shaver blades occurred after soft-tissue resection; however, with bone resection, progressive blunting of the shaver blades was observed.Arthroscopic shavers can be tested in a controlled setting. The performance of the tested shaver types appears to be fairly independent of the manufacturer. For tendon resection, a smooth outer blade and serrated inner blade were optimal.This is one of the first established independent and quantitative assessments of arthroscopic shaver systems and blades. We believe that this study will assist the surgeon in choosing the optimal tool for the desired effect.

Background:The structural failure rate of rotator cuff repair can exceed 50%. Important predictors for repair failure are preoperative fatty muscle infiltration and myotendinous retraction.Purpose:To quantitatively assess the prognostic value of preoperative retraction of both the supraspinatus muscle and tendon for the outcome of supraspinatus repair.Study Design:Cohort study; Level of evidence, 3.Methods:In 33 shoulders with complete supraspinatus tendon ruptures subjected to arthroscopic repair, magnetic resonance imaging (MRI) scans taken preoperatively and after a mean follow-up of 24 months were studied. The exact position of the lateral extension of the supraspinatus muscle and of the tendon end was evaluated and correlated with the preoperative stage of fatty infiltration (Goutallier) and the failure rate of tendon repair.Results:The mean lengthening of the muscle and tendon end was −3 mm and 4 mm in the failed repairs (n = 19) and 14 mm and 8 mm in the successful repairs (n = 14). If the supraspinatus had preoperative Goutallier stages 2 to 3 and a tendon length of less than 15 mm, the failure rate was 92%, but if the tendon length was greater than 15 mm, the failure rate was only 33%. With Goutallier stages 0 to 1, the corresponding failure rates were 57% and 25%, respectively.Conclusion:Rotator cuff repair lengthens the tendon, even if the repair fails. The possibility to lengthen the myotendinous unit is related to the preoperative length of the tendon. The combination of Goutallier grading and preoperative tendon length appears to be a more powerful predictor for the reparability of a tendon tear than Goutallier grading alone.

Purpose: This study was designed to compare the pull-out strength of simple suture stitches in human supraspinatus tendons with respect to the position of the rotator cable. Methods: Fifty-four tests were performed on 6 intact, human supraspinatus tendons, to assess the cutout strength of a simple suture configuration in different positions; medial to, lateral to, or within the rotator cable. Tendon thickness was measured and correlated for each positioned suture. Results: Suture positioning lateral to or in the rotator cable showed significantly lower suture retention properties compared with positioning the suture medial to the cable (p=0.002). In all tested specimens, the central stitch in the row medial to the rotator cable provided the optimum retention properties (mean: 191N; SD:±44; p

Background A well-defined, reproducible small animal model that allows quantitative assessment of musculotendinous changes would be desirable for investigations concerning rotator cuff pathology. Methods The supraspinatus tendon was released by osteotomy of the greater tuberosity in seven New Zealand rabbits. The musculotendinous unit was then allowed to retract during 6 weeks. Retraction was monitored with computed tomography (CT). At sacrifice, CT measurements of retraction were validated by measurement of the total length of the musculotendinous unit after sacrifice and by correlation with functional and structural properties of the musculotendinous unit at tendon release and at sacrifice. Results Mean (SD) retraction of the musculotendinous unit was 1.8 (0.2) cm on CT, precisely, and negatively correlated with the total length of the retracted musculotendinous unit at sacrifice ( r = –0.87, p = 0.011) but not significantly correlated with CT measurements of atrophy ( r = 0.20, p = 0.699) or fatty infiltration ( r = 0.13, p = 0.78). Mean (SD) muscle work decreased from 1.6 (0.23) Nm to 1.2 (1) Nm ( p = 0.056). Mean (SD) muscle fibre diameter decreased from 65 (10) μm to 48 (16) μm ( p = 0.063). This decrease was significantly correlated with the amount of fatty infiltration ( r = 0.79, p = 0.033). Discussion Tendon release using osteotomy of the rabbit greater tuberosity allows precise measurement of musculotendinous retraction and offers the possibility for functional muscular testing. Changes in the rabbit supraspinatus muscle caused by myotendinous retraction correspond to those observed in established sheep models.

The suture-tendon interface is often the weakest link in tendon to bone repair of massive rotator cuff tears. Genipin is a low-toxicity collagen crosslinker derived from the gardenia fruit that has been shown to augment collagen tissue strength and mechanically arrest tendon-tear progression. The purpose of the current study was to evaluate whether genipin crosslinking can sufficiently augment the suture-tendon interface to improve suture pullout strength using simple single-loop sutures and the modified Mason-Allen technique. The study also aimed to assess whether time of genipin treatment is a relevant factor in efficacy. In an ex vivo (cadaveric) sheep rotator cuff tendon model, a total of 142 suture pullout tests were performed on 32 infraspinatus tendons. Each tendon was prepared with three single-loop stitches. Two groups were pretreated by incubation in genipin solution for either 4 hours or 24 hours. Two corresponding control groups were incubated in phosphate buffered saline for the same periods. The same test protocol was applied to tendons using modified Mason-Allen technique stitch patterns. Each suture was loaded to failure on a universal materials testing machine. Suture pullout force, stiffness, and work to failure were calculated from force-displacement data, and then compared among the groups. Median single-loop pullout force on tendons incubated for 24 hours in genipin yielded an approximately 30% increase in maximum pullout force for single-loop stitches with a median of 73 N (range, 56–114 N) compared with 56 N (range, 40–69 N; difference of medians = 17 N; p = 0.028), with corresponding increases in the required work to failure but not stiffness. Genipin treatment for 4 hours showed no added benefit for suture-pullout behavior (46 N, [range, 35–95 N] versus 45 N, [range, 28–63 N]; difference of medians, 1 N; p = 1). No tested genipin crosslinking conditions indicated benefit for tendons grasped using the modified Mason-Allen technique after 4 hours (162 N, [range, 143–193 N] versus 140 N, [range, 129–151 N]; difference of medians, 22 N; p = 0.114) or after 24 hours of crosslinking (172 N, [range, 42–183 N] versus 164 N [range, 151–180 N]; difference of medians, 8 N; p = 0.886). Exogenous collagen crosslinking in genipin can markedly improve resistance to pullout at the tendon-suture interface for simple stitch patterns while the modified Mason-Allen stitch showed no benefit in an ex vivo animal model. Tendon strength augmentation by genipin pretreatment offers the potential to improve suture retention properties. Future studies are warranted for the development of clinically viable intraoperative delivery strategies and in vivo testing for safety and efficacy.

The long-term results over 20 years following meniscal repair in stable knees have not been described yet. The objective was therefore to analyze the clinical and radiological outcomes of successful, isolated, open meniscal repairs with an intact ACL after a mean follow-up of 20.6 years (range, 16-25) retrospectively in 26 patients. Clinical evaluation included objective (Lysholm, IKDC, Tegner) and subjective scores. Standard radiological assessment according to Ahlbäck's osteoarthritis classification and weight-bearing full-leg radiography for alignment were performed. Eight patients were excluded due to a re-rupture of the meniscus. In the 18 remaining patients (12 male, 6 female), the mean Lysholm and IKDC score was 97.8 points (range, 85-100) and 93% (range, 77-100) at the most recent follow-up, respectively. The Tegner activity scale averaged 4.2 (range, 3-7). Subjectively, 13 patients rated their outcome excellent, 4 good, and 1 fair. The radiological evaluation demonstrated an average development of "+1" grade (range, 0-"+2") osteoarthritic changes versus preoperatively; however, the contralateral healthy knee also revealed comparable (on average "+1" grade) degenerative changes reflecting natural history. The alignment was not significantly different between the operated and the contralateral leg. Overall, isolated open meniscal repair in stableness has the potential of a successful surgery with good to excellent long-term results. The development of osteoarthritic changes within the femorotibial compartments is mild and comparable to contralateral and the alignment of the axis is preserved. Therefore, repair of a ruptured meniscus is recommended whenever possible, even in isolated meniscal tears. However, a re-rupture rate of approximately 30% in isolated meniscal tears has to be acknowledged, which still reflects the need for biological enhancement of meniscal healing.

Purpose The indication for operative treatment of displaced midshaft clavicle fractures remains controversial. However, if plate fixation is considered, implant prominence and skin irritation are the most common causes for re-operation. Low profile implants as well as closely contouring plates to the individual anatomy may reduce these complications. The aim of this study was to compare the fitting accuracy and implant prominence of 3.5 mm pelvic reconstruction plates (PRP) with pre-contoured anatomical clavicle plates (PACP) for midshaft clavicle fractures. Methods Three-dimensional data of the largest, median and smallest male and female clavicle of an existing database of 89 cadaveric clavicles were included for analysis. A three-dimensional model of a commercially available PACP was used for digitally positioning of the plate on the segmented clavicles. Three-dimensional printouts of each clavicle were produced and the 3.5 mm reconstruction plates were manually bent and positioned by the senior author. Computed tomography scans and three-dimensional reconstructions were then obtained to digitally compare the fitting accuracy and implant prominence. Results Pelvic reconstruction plates offered superior fitting accuracy and lower implant prominence compared to PACP. The largest difference in implant prominence was observed in large sized female clavicles and measured 3.6 mm. Conclusion Both, the less costly PRP plates and commercially available PACP for midshaft fractures of the clavicle demonstrated a clinically acceptable fitting accuracy. The manually bent pelvic-reconstruction plates demonstrated reduced implant prominence with superior fitting. Hypothetically, this might contribute to a reduced rate of reoperation. Level of evidence Level IV cadaveric study.

In unicondylar knee prostheses, the relative angle and congruency of the femoral against the tibial component is not mechanically constrained and may vary with the surgical implantation technique. The contact area between both components was measured with increasing varus (0-20 degrees) and flexion angles (-20 degrees to 90 degrees) in five prosthesis models in the laboratory. The contact area varied with the relative position of the components and was critically reduced up to 70% at a varus range between >5 degrees and

The treatment of periprosthetic joint infection (PJI) of the shoulder with two-stage revision arthroplasty using an antibiotic-loaded cement spacer is established strategy, but there is sparse information regarding the likelihood of infection control and restoration of shoulder.(1) What is the likelihood of infection control after two-stage revision using an antibiotic cement spacer for patients with PJI of the shoulder? (2) What are the improvements in Constant and Murley scores at 2 years after these staged revisions?Between 2000 and 2013, we treated 48 patients with PJI of the shoulder using two-stage revision including an antibiotic-containing cement spacer during the first stage. Of those, 38 (79%) were available for review at a minimum of 24 months (mean, 52 ± 34 months). Ten patients (21%) were excluded because they were deceased (n = 3), moved abroad (n = 4), or refused followup (n = 3), leaving 38 for analysis in this retrospective study. During the first stage, removal of the prosthesis, débridement, and implantation of a gentamicin and vancomycin-filled cement spacer were performed by four different surgeons followed by antibiotic therapy (2 weeks intravenous plus 10 weeks oral). For the second stage, we generally tried a reverse total shoulder arthroplasty (RTSA; n = 26). In case of severe glenoid destruction, hemiarthroplasty (HA; n = 8) was used as a salvage option. In 14 patients the cement spacer was left in place because the patients refused further surgery or were not operable owing to medical reasons. The primary outcome included the proportion of patients achieving infection control 2 years after the second-stage procedure after implantation of the cement spacer. Infection control was determined as the absence of the Musculoskeletal Infection Society PJI criteria. The clinical outcome assessed with the Constant and Murley scores served as the secondary outcome parameter. A subgroup (RTSA; HA, spacer retention) analysis of the Constant and Murley scores was performed.Successful infection control was achieved in 36 of 38 patients (95%). Patients who underwent treatment with a cement spacer had increased Constant and Murley scores at latest followup compared with their pretreatment scores (mean ± SD, 27 ± 19 versus 43 ± 20; mean difference, 17; 95% CI, 10-24; p = 0.001). For patients who underwent staged treatment followed by second-stage RTSA (n = 23), the Constant and Murley scores increased (mean ± SD, 31 ± 20 versus 51 ± 20; mean difference, 20; 95% CI, 11-30; p = 0.001). The Constant and Murley scores did not improve in patients who underwent HA (mean ± SD, 22 ±15 versus 24 ± 90; mean difference, 3; 95% CI, -10 to 16; p = 0.509) or who retained the spacer (mean ± SD, 18 ±12 versus 35 ±10; mean difference, 19; 95% CI, -5 to 44; p = 0.093).Revision arthroplasty using an antibiotic-loaded cement spacer provided successful infection control in patients with periprosthetic shoulder infections in this small, retrospective series. Functional improvement was obtained after reimplantation of a reverse total shoulder prosthesis but was not seen after HA and cement spacer; however, baseline differences among patient groups very likely contributed to these differences, and they should not be attributed to implant selection alone.Level III, therapeutic study.

During arthroscopic knot tying, one of the suture limbs may break before completion of the knot. With a single suture limb left, it may not be possible to secure the knot against slipping, and the surgeon may be forced to use an additional anchor to obtain a secure repair. We present a tool and method that allow completion of the knot on a single suture limb. Alternatively, the method can be used to perform all-inside endoscopic or arthroscopic knot tying without removal of the instrument from the body.

In 13 patients, the development of supraspinatus muscle atrophy and fatty infiltration after rotator cuff tendon repair was quantified prospectively via magnetic resonance imaging. Intraoperative electrical nerve stimulation at repair showed that the maximal supraspinatus tension (up to 200 N) strongly correlated with the anatomic cross-sectional muscle area and with muscle fatty infiltration (ranging from 12 N/cm(2) in Goutallier stage 3 to 42 N/cm(2) in Goutallier stage 0). Within 1 year after successful tendon repair (n = 8), fatty infiltration did not recover, and atrophy improved partially at best; however, if the repair failed (n = 5), atrophy and fatty infiltration progressed significantly. The ability of the rotator cuff muscles to develop tension not only correlates with their atrophy but also closely correlates with their degree of fatty infiltration. With current repair techniques, atrophy and fatty infiltration appear to be irreversible, despite successful tendon repair. Unexpectedly, not only weak but also very strong muscles are at risk for repair failure.

Acetabular retroversion has been proposed to contribute to the development of osteoarthritis of the hip. For the diagnosis of this condition, conventional AP pelvic radiographs may represent a reliable, easily available diagnostic modality as they can be obtained with a reproducible technique allowing the anterior and posterior acetabular rims to be visible for assessment. This study was designed to: (i) determine cranial, central, and caudal anatomic acetabular version (AV) from cadaveric specimens; (ii) establish the validity and reliability of the radiographic measurements of central acetabular anteversion; and (iii) determine the validity and reliability of the radiographic "cross-over-sign" to detect acetabular retroversion. Using 43 desiccated pelvises (86 acetabuli) the anatomic AVs were measured at three different transverse planes (cranially, centrally, and caudally). From these pelvises, standardized AP pelvic radiographs were obtained. To directly measure central AV, a modified radiographic method is introduced for the use of AP pelvic radiographs. The validity and reliability of this radiographic method and of the radiographic cross-over-sign to detect cranial acetabular retroversion were determined. The mean central and caudal anatomic AVs were approximately 20 degrees , and the mean cranial AV was 8 degrees . Cranial retroversion (AV < 0 degrees ) was present in 19 of 86 hips (22%). A linear correlation was found between the central and cranial AV. Below 10 degrees of central AV, all acetabuli were cranially retroverted. Between 10 degrees and 20 degrees , 30% of the acetabuli were cranially retroverted, and above 20 degrees , only 1 of 45 acetabuli was cranially retroverted. The radiographic measurement of the central AV (20.3 +/- 6.5 degrees ) correlated strongly with the anatomic AV (20.1 +/- 6.4 degrees ). The sensitivity of the cross-over-sign to detect a cranial acetabular anteversion of less than 4 degrees was 96%, its specificity 95%, and the positive predictive and negative predictive values 90% and 98%, respectively. Both the modified radiographic anteversion measurements and the cross-over-sign demonstrated substantial inter- and intraobserver reliability. Retroversion is almost exclusively a problem of the cranial acetabulum. The cranial AV is on average 12 degrees lower than the central AV, with the latter directly measurable from AP pelvic radiographs. A central AV of less than 10 degrees was associated with cranial retroversion. The presence of a positive cross-over-sign is a highly reliable indicator of cranial AV of

Background In wheelchair-dependent individuals, pain often develops because of rotator cuff tendon failure and/or osteoarthritis of the glenohumeral joint. The purposes of this study were to investigate (1) specific rotator cuff tear patterns, (2) structural healing, and (3) clinical outcomes after arthroscopic rotator cuff repair in a cohort of wheelchair-dependent patients. Methods Forty-six shoulders with a mean follow-up of 46 months (range, 24-82 months; SD, 13 months) from a consecutive series of 61 shoulders in 56 patients (46 men and 10 women) undergoing arthroscopic rotator cuff repair were available for analysis. Clinical outcome analysis was performed using the Constant-Murley score, the Subjective Shoulder Value, and the American Shoulder and Elbow Surgeons score. The integrity of the repair was analyzed by ultrasound. Results Of the shoulders, 87% had supraspinatus involvement, 70% had subscapularis involvement, and 57% had an anterosuperior lesion involving both the supraspinatus and subscapularis. Despite an overall structural failure rate of 33%, the patients showed improvements in the Constant-Murley score from 50 points (range, 22-86 points; SD, 16 points) preoperatively to 80 points (range, 40-98 points; SD, 12 points) postoperatively and in the American Shoulder and Elbow Surgeons score from 56 points (range, 20-92 points; SD, 20 points) preoperatively to 92 points (range, 53-100 points; SD, 10 points) postoperatively, with a mean postoperative Subjective Shoulder Value of 84% (range, 25%-100%; SD, 17%). Conclusion Failure of the rotator cuff in weight-bearing shoulders occurs primarily anterosuperiorly. Arthroscopic rotator cuff repair leads to a structural failure rate of 33% but satisfactory functional results with high patient satisfaction at midterm follow-up.

Purpose To determine conditions for the safe use of radiofrequency (RF) tissue ablation probes that avoid damaging suture material. Methods Four sutures made of 3 different materials commonly used in arthroscopic procedures were analyzed in a saline bath related to effects of RF-produced heat by proximity, duration, and intensity settings measuring burn-through time and ultimate load to failure. The parameters tested were electrode-to-suture distance, power setting, and the presence of tendon tissue or metallic anchor eyelets. Outcome variables were the burn-through time and the ultimate failure load of differently treated suture samples. Results Mean burn-through time for suture in direct contact with the RF probe ranged from 57.2 to 14.7 seconds for ultra-high-molecular-weight polyethylene (UHMWPE) sutures, 1.1 seconds for polydioxanone suture, and 0.8 seconds for polyethylene terephthalate suture. One of the UHMWPE sutures was capable of withstanding 3 seconds of direct contact with the RF probe without any compromise in tensile strength. No suture material tested had any mechanical change as long as the RF probe was kept 1 mm from the suture. Conclusions Heat from RF tissue ablation probes can cause undetected damage. High-strength UHMWPE sutures were less sensitive to an RF treatment than polyester sutures. The use of different test substrates did not significantly influence the burn through time. Clinical Relevance Heat from RF probes can damage some suture material if direct contact is made even briefly. The use of RF devices may be safe for the suture when a distance between probe and suture of >1 mm is maintained. Suture made from UHMWPE may tolerate up to 3 seconds of RF probe contact and not sustain significant damage. Surgeons must use great care when using RF devices in the vicinity of suture placement.

Purpose: Chronic tearing of tendons is associated with molecular and structural alterations causing biomechanical changes, which compromise musculotendinous function and become limiting factors for tendon repair. This study investigated the histological response of chronically retracted sheep rotator cuff tendons to mechanical and pharmacological stimulation in view of tendon repair. Methods: Sixteen weeks after experimental release of the infraspinatus tendon in 20 sheep, the retracted musculotendinous unit was subjected to continuous traction either with [anabolic steroids (nandrolone) group/insulin-like growth factor (IGF) group] or without (control group) additional pharmacological treatment during 6weeks. A new degeneration score for tendinous tissues (DSTT), based on established knowledge on histological changes associated with tendon degeneration, was used for histological analysis at the time of tendon release, at the beginning of continuous re-lengthening and at repair in all animals. Results: The DSTT score (inter-observer correlation: r=0.83), quantifiably representing tendon degeneration, improved from 15.5 (SD 1.3) points before to 9.8 (SD 3.8) points after re-lengthening. It improved in a qualitatively and quantitatively similar fashion if pharmacological stimulation was added. The nandrolone group improved from 13.7 (SD 1.6) to 9.8 (SD 1.9) and the IGF group from 13.3 (SD 3.6) to 8.8 (SD 1.8) points. Conclusion: Mechanical stimulation significantly reduced tissue degeneration. However, the addition of a pharmacological stimulation with anabolic steroids or IGF had neither a measurable positive nor negative effect on the degenerative process. Therefore, this investigation does neither support the additional pharmacological use of the anabolic steroid nandrolone or of IGF decanoate for restoration of tendon degeneration, nor otherwise provide evidence for additional tendon damage, if those substances are used to alter the muscular metabolism.

Background It was the purpose of this paper to analyze structural, functional, and electrophysiologic variables that may determine preserved overhead function for patients with massive rotator cuff tears. Methods Nineteen patients (20 shoulders) were prospectively included in either the pseudoparalytic (n = 9) or the non-pseudoparalytic group (n = 11). Fatty infiltration was graded according to Goutallier, and anterior (subscapularis) and posterior (infraspinatus and teres minor) tear extension was graded 0 (no involvement) to 4 (full tear) on magnetic resonance imaging. Glenohumeral and scapulothoracic rhythm was assessed by fluoroscopic motion analysis, and electromyographic evaluation of the deltoid muscle was performed. Results We found no significant difference of fatty infiltration of the supraspinatus (3.9 vs 3.6), infraspinatus (3.9 vs 3.8), and teres minor (1.7 vs 0.6) or of the posterior tear extension (2.6 vs 2.0) between pseudoparalytic and non-pseudoparalytic shoulders. Global tear extension in the parasagittal plane (205° vs 163°) and subscapularis involvement (2.6 vs 1.2), however, showed significant differences between the two groups, and no patient with a full-thickness supraspinatus and infraspinatus tear with extension into the inferior half of the subscapularis was able to lift the arm to 90°. Fluoroscopic assessment revealed almost total loss of active glenohumeral abduction in the pseudoparalytic group. Conclusion Despite global tear extension, the single most important predictor for preserved shoulder function is the integrity of the inferior subscapularis insertion. Furthermore, electromyographic evaluation identifies a well-differentiated deltoid innervation as beneficial for a well-preserved shoulder function, but it does not protect from pseudoparalysis.

Background To compare instruments designed for arthroscopic suture handling during arthroscopic rotator cuff repair, to assess the force needed to penetrate the tendon, and to evaluate the residual defect size. Methods Twenty-one instruments were each tested ten times on thawed sheep infraspinatus tendons. The force needed to pierce the tendon with each instrument was measured using a custom setup. Bone wax plates were used to make the perforation marks visible and to quantify the lesions each instrument created. Results The force to pierce a tendon had a range of 5.6–18.5 N/mm. Within the group of suture retrievers, the angled instruments required in average 85 % higher forces than straight instruments. The lesion area had a range of 2–7 mm2. Suture retrievers produced significantly larger lesion sizes compared with suture shuttles. Conclusion For the identical task of passing a suture through a tendon, differences exist regarding the ease of tendon penetration and potential damage to the tendon for different tools. The design, function, and resulting lesion size may be relevant and important for surgical handling and to avoid excess structural damage to the tendon. These results suggest that choosing the most appropriate tools for arthroscopic suture stitching influences the ease of handling and final integrity of the tissue. Level of evidence Mechanical evaluation of surgical devices. Electronic supplementary material The online version of this article (doi:10.1186/s12891-015-0794-9) contains supplementary material, which is available to authorized users.

We released the infraspinatus tendons of six sheep, allowed retraction of the musculotendinous unit over a period of 40 weeks and then performed a repair. We studied retraction of the musculotendinous unit 35 weeks later using CT, MRI and macroscopic dissection. The tendon was retracted by a mean of 4.7 cm (3.8 to 5.1) 40 weeks after release and remained at a mean of 4.2 cm (3.3 to 4.7) 35 weeks after the repair. Retraction of the muscle was only a mean of 2.7 cm (2.0 to 3.3) and 1.7 cm (1.1 to 2.2) respectively at these two points. Thus, the musculotendinous junction had shifted distally by a mean of 2.5 cm (2.0 to 2.8) relative to the tendon. Sheep muscle showed an ability to compensate for approximately 60% of the tendon retraction in a hitherto unknown fashion. Such retraction may not be a quantitatively reliable indicator of retraction of the muscle and may overestimate the need for elongation of the musculotendinous unit during repair.

Purpose: This study was designed to comprehensively compare the mechanical properties of 4 types of braided polyblend sutures with widely used braided polyester and monofilament polydioxanone sutures. Methods: Polyblend polyethylene sutures (FiberWire [Arthrex, Naples, FL], Herculine [Linvatec, Largo, FL], Orthocord [DePuy Mitek, Raynham, MA], and Ultrabraid [Smith & Nephew Endoscopy, Andover, MA]), a braided polyester suture (Ethibond; Ethicon, Somerville, NJ), and an absorbable monofilament polydioxanone suture (PDS II; Ethicon), all USP No. 2, were mechanically tested. Fraying resistance was tested on eyelets of metallic and absorbable suture anchors. Cartilage abrasion caused by an intra-articularly placed suture knot was simulated by fraying on distal porcine femora. Results: All polyblend sutures were stronger than Ethibond or PDS II sutures by at least a factor of 2, with or without a knot. When knotted, Herculine (261 ± 44 N) was strongest, followed by Ultrabraid (244 ± 3 N). FiberWire was most resistant against fraying on metallic anchors. Orthocord was by far least abrasive with absorbable anchors. Resistance to fraying was 100- to 500-fold (absorbable anchors) and 6- to 30-fold (metallic anchor) better for all polyblend sutures than for Ethibond. All braided sutures caused a similar amount of abrasion of joint cartilage, but they caused significantly more abrasion (>20-fold) than the monofilament degradable suture. Conclusions: The ultimate strength of polyblend suture material was 2- to 2.5-fold greater than that of polyester or polydioxanone sutures, but the resistance to fraying was up to 500-fold greater than that of polyester or polydioxanone sutures. With regard to strength, this makes polyblend sutures particularly advantageous for use with metallic edges of anchors or prostheses or with absorbable anchor eyelets. Clinical Relevance: With a high resistance to fraying against metallic edges or a decrease in cutting of absorbable suture eyelets being up to 500-fold greater than with polyester or polydioxanone sutures, the new polyblend sutures appear to fill a void in the armamentarium of the surgeon, provided that at least 2 throws more than with conventional sutures are used for knot tying.

Early radiographic detection of femoroacetabular impingement might prevent initiation and progression of osteoarthritis. The structural abnormality in femoral-induced femoroacetabular impingement (cam type) is frequently asphericity at the anterosuperior head/neck contour. To determine which of six radiographic projections (anteroposterior, Dunn, Dunn/45 degrees flexion, cross-table/15 degrees internal rotation, cross-table/neutral rotation, and cross-table/15 degrees external rotation) best identifies femoral head/neck asphericity, we studied 21 desiccated femurs; 11 with an aspherical femoral head/neck contour and 10 with a spherical femoral head/neck contour. To radiographically quantify femoral head asphericity, we measured the angle where the femoral head/neck leaves sphericity (angle alpha). The aspherical femoral head/neck contours had a greater maximum angle alpha (70 degrees ) compared with the spherical head/neck contours (50 degrees ). The angle alpha varied depending on the radiographic projection: it was greatest in the Dunn view with 45 degrees hip flexion (71 degrees +/- 10 degrees ) and least in the cross-table view in 15 degrees external rotation (51 degrees +/- 7 degrees ). Diagnosis of a pathologic femoral head/neck contour depends on the radiologic projection. The Dunn view in 45 degrees or 90 degrees flexion or a cross-table projection in internal rotation best show femoral head/neck asphericity, whereas anteroposterior or externally rotated cross-table views are likely to miss asphericity. Level of Evidence: Prognostic study, level II-1 (retrospective study).

Background: Clinical measurement of passive dorsiflexion of the ankle joint is essential for the diagnosis of various pathologic conditions of the foot and ankle but is of unreliable precision with high interobserver variability in nonweightbearing tests. This work was designed to develop and test a precise, standardized, and reliable technique for measurement of passive and active ankle range of motion. Methods: The proposed measurement tool is composed of two mobile parallelograms, one attached to the tibia, the second one to the plantar surface of the foot. The parallelograms are connected with a hinge with an angular scale to measure the angle between the foot and tibia. Results: Interobserver correlation between clinical measure-ments for maximal passive foot dorsiflexion were 0.03 with knee extension and 0.38 with knee flexion, while for measurements with the proposed tool they reached 0.89 and 0.97, respectively, with a mean measurement error of 0.9 degrees. Intraobserver correlations reached values of r = 0.98 and 0.99. Conclusions: The proposed tool allows measurement of the ankle range of motion with very high precision and reproducibility far superior to clinical measurements. Clinical Relevance: Precise measurement of ankle range of motion is clinically challenging. With the use of the proposed tool, measurement precision and reliability are decisively improved.

Background Treatment of glenohumeral osteoarthritis in young patients is challenging. Total shoulder arthroplasty reliably addresses pain and dysfunction but compromises glenoid bone stock. Various efforts have been made to avoid a prosthetic glenoid component or to prevent glenoid erosion after hemiarthroplasty. Capsular interposition, meniscal allograft, and more recently, GraftJacket (Wright Medical Technology Inc, Arlington, TN, USA), a human dermal collagen allograft, have been proposed for interposition arthroplasty in young patients with glenohumeral osteoarthritis. Methods From 2009 to 2010, GraftJacket was used for glenoid resurfacing combined with humeral resurfacing or a stemmed hemiarthroplasty in 6 patients with a mean age of 47 years (34-57 years). Before GraftJacket was available, 5 patients were treated with a meniscal allograft and 6 with capsular interposition arthroplasty. Results At a mean of 16 months (9-22 months) after the GraftJacket was implanted, 5 of the 6 patients were revised to a total shoulder arthroplasty or a reverse total shoulder arthroplasty. The sixth patient was dissatisfied but declined further surgery. The mean relative, preoperative Constant score decreased from 35% (range, 13%-61%) to 31% (range, 15%-43%) at revision or latest follow-up. Of the 5 patients with meniscal allograft, 3 underwent revision at a mean of 22 months (range, 12-40 months), and 4 of the 6 patients with capsular interposition were revised at a mean of 34 months (range, 23-45 months). The mean relative Constant scores preoperatively and at revision or latest follow-up were 44% (range, 19%-68%) and 58% (range, 9%-96%) for the meniscal allograft patients and 47% (range, 38%-62%) and 63% (range, 32%-92%) for the capsular interposition cases. Conclusion In our hands, 3 different types of biological resurfacings combined with humeral hemiarthroplasty have an unacceptable early failure rate.

To prospectively evaluate the accuracy of ultrasonography (US) in depicting fatty atrophy of the supraspinatus (SSP) and infraspinatus (ISP) muscles, with magnetic resonance (MR) imaging as the reference standard.Institutional review board approval and informed consent were obtained. SSP and ISP muscles of 65 consecutive patients (27 women, 38 men; mean age, 53.1 years; range, 28-83 years) with possible rotator cuff tears were evaluated with US in two planes. Visibility of muscle contour, pennate pattern, the central tendon, and muscle echogenicity was assessed by two radiologists. On the basis of these findings, diagnosis of substantial fatty atrophy was made at US. Accuracy, sensitivity, specificity, proportion of over- and underestimations, and interobserver agreement in diagnosis of substantial (grade 2 or greater) muscle atrophy were determined. Fatty atrophy was graded at MR imaging as follows: score of 0 = no intramuscular fat, score of 1 = some fatty streaks, score of 2 = fat evident but less extensive than muscle, score of 3 = fat equal to muscle, and score of 4 = fat more extensive than muscle.For readers 1 and 2, the accuracy of US in depicting fatty atrophy of SSP muscle was 75% (49 of 65) and 72% (47 of 65), sensitivity was 89% (eight of nine) and 100% (nine of nine), and specificity was 73% (41 of 56) and 68% (38 of 56), respectively. For readers 1 and 2, the accuracy of US in depicting fatty atrophy of ISP muscle was 85% (55 of 65) and 80% (52 of 65), sensitivity was 58% (11 of 19) and 63% (12 of 19), and specificity was 96% (44 of 46) and 87% (40 of 46), respectively. Overestimation of SSP muscle atrophy was more common (23% [15 of 65] for reader 1 and 28% [18 of 65] for reader 2) than underestimation (2% [one of 65] for reader 1 and 0% [0 of 65] for reader 2). For readers 1 and 2, overestimation of ISP muscle atrophy was 3% (two of 65) and 9% (six of 65) and underestimation was 12% (eight of 65) and 9% (seven of 65), respectively. Interobserver agreement was moderate for SSP (kappa = 0.55) and substantial for ISP (kappa = 0.71) muscles.US is moderately accurate in the diagnosis of substantial fatty atrophy of the SSP or ISP muscle.

The biological reaction on implant surfaces is of key importance for the integration of implants into the surrounding tissue. In the present study, a new set-up for the preparation of different surfaces with identical surface chemistry is presented. Using this technique, we investigated the effects of surface microstructuring on cell performance using adult, rat bone marrow cells as a tool. Our results indicate that cell morphology was strongly affected by the kind of surface microstructuring. Effects on cell culture biochemical characteristics did not always correlate with effects on cell morphology and cell culture appearance.

Rotator cuff tendon repair may fail for various reasons. Although the role of repair techniques and of the musculotendinous unit has been studied, there is little information on the quality of the bone to which the tendon is to be repaired. Therefore, 14 cadaveric humeral heads, 7 specimens without and 7 with a full-thickness rotator cuff tendon tear, were quantitatively assessed by use of high-resolution micro-computed tomography. Bone density is higher below the articular surface than in the greater tuberosity (40% vs 10%-20%), and tendon tears are associated with a reduction in cancellous bone density of greater than 50%, leading to a virtually hollow greater tuberosity, with intact cortical bone. The results found suggest that in long-standing rotator cuff tears, creating a deep trough should be avoided to achieve reliable tendon-to-bone contact. For optimal suture fixation to bone, sutures or anchors should be positioned subcortically or medially under the articular surface.

Absorbable implant materials offer various advantages but are mechanically far weaker than metals. Despite known temperature dependence of the biomechanical properties of these materials, mechanical testing has almost exclusively been performed at room temperature in the literature. In this study, the difference in mechanical performance at room and body temperature was assessed in vitro at different test speeds.Biomechanical bench study.Five absorbable suture anchor models were held in a metallic holder and loaded under tension using 0.5-mm steel wires until failure. Testing temperature was 20 degrees C +/- 1 degrees C or 37 degrees C +/- 1 degrees C, test speed was 50 mm/min or 5 mm/min. Tensile load at failure and failure mode were recorded. To test creep behavior, a constant load of 100 N was applied, and time to failure was recorded at both temperatures.Both raising the temperature and decreasing test speed significantly (P.0001) impaired the mechanical performance of the tested implants. Increase of temperature (20 degrees C to 37 degrees C) resulted in a decrease of the maximal failure strength by up to 40% and decreased time to failure by up to 98% under static load. At 37 degrees, decreasing the test speed from 50 to 5 mm/min lowered the load to failure by up to 18%. Failure of the anchors always occurred by eyelet cutout of the wire.The lower the test speed, the higher is the influence of the testing temperature. Testing of implants at room temperature instead of body temperature may falsely improve test results by a factor of up to 50 under static load. Therefore, testing absorbable implants at body temperature seems mandatory, preferably at slow test speeds.

Tendon tension in vivo may be determined indirectly by measuring intratendinous pressure, by using a buckle transducer or by measuring the tendon strain. All of these methods require appropriate calibration, which is highly dependent on various variables. To measure the tendon load in vivo during a period of 2 weeks in sheep, a measurement technique has been developed using a force sensor interposed serially between the humeral head and the tendon end. Within a supporting frame, a flexion-sensitive force transducer is subjected to three-point bending stress. The load is transmitted by sutures from the tendon end through a hole in the sensor frame, orthogonal to the force transducer. In this configuration, the sensor measures the tensile force acting on the tendon, largely independent of the loading direction. The sensor was screwed to the humeral head and connected to the tendon end which was previously released from its insertion site along with a bone chip, using sutures. Connecting wires passed subcutaneously to a skin outlet about 30 cm away from the transducer. The sensor output was linear to the measured load up to 300 N, with maximum hysteresis of 18% full scale. All sensors worked in vivo without drift over a period of up to 14 days with no change in the calibration data. Forces up to 310 N have been recorded in vivo with daily tension measurements. This study shows that serial tendon tension measurement is feasible and allows for reliable, repeatable recording of the absolute tendon tension at the expense of tendon integrity.

Objective. To develop and test a new cerclage wire tightening technique, yielding reproducibly maximal pre-tension, load to failure and minimal elongation to failure of the wire junction. Design. Laboratory bench study. Background. Cerclage wire fixation is difficult to perform by hand with reproducible quality and tightening tension, which are required for optimal performance. Methods. With the new technique, 1, 1.25 and 1.5 mm steel wires were passed through a 9 × 18 mm steel tube, grasped using a modified ASIF wire-tightener and tightened by twisting until spontaneous failure of the wires in the tube. These fixations were compared to wires pre-tightened by hand to controlled high or low pre-tension using the simple twist, the knot twist and twist secured against untwisting, loaded to failure on a testing machine. The tests assessed pre-tension, ultimate failure load and elongation to failure. Results. Wire twists performed with the new technique were always perfectly symmetrical and may be tightened to maximal pre-tension without weakening of the wire. The twist secured against untwisting combined high stiffness with high failure load. The knot twist elongates to an unacceptable degree, unlike the secured twist. The simple twist untwists under little tension. Conclusions. The new technique allows to obtain maximal pre-tension and thus minimal elongation to failure of simple wire twists, without having to worry about breaking the wire at the base of the twist due to over-tightening. Relevance Cerclage wire fixation is an effective and cheap method to perform osteosynthesis. For adequate performance, maximal pre-tension, symmetrical twisting and high load to failure are necessary. The here presented technique combines all of these pre-requisites in a simple fashion.

Purpose: Absorbable suture anchors offer great advantages but are made of mechanically weak material. The weakest link in the fixation of soft tissue to bone may therefore be the anchor itself. In this study, several commercially available anchors were mechanically tested in vitro. Type of study: Biomechanical bench study. Methods: Twelve absorbable suture anchor models were implanted into an artificial test bone according to the recommended technique. Testing temperature was 37°C ± 1°C. The anchors were loaded with an Instron testing machine with the suture material (USP No. 2, Ethibond, Ethicon, Somerville, NJ) in line with the anchor axis, with and without previous abrasion of the suture at the eyelet. Tensile load at failure and failure mode were recorded. To test creep behavior, a permanent load of 100 N was applied to the anchors, and time to failure was recorded. Suture anchor weight and crystallinity were analyzed. Results: Mean failure load on tensile testing using a cross-head speed of 60 mm/min ranged from 124 to 244 N. Failure modes were eyelet failure in 5 cases, suture failure in 6 cases, and anchor pullout in 1 case. In creep testing, eyelet failure occurred in 8 anchor models after a mean duration of 0.5 to 99 hours; 3 anchor models remained intact after 300 hours, and 1 anchor model failed by pullout of the test sample. Crystallinity ranged from 0% (amorphous) to 57.2%; anchor weight ranged from 0.036 to 0.161 g. Mechanical properties did not correlate with crystallinity but with anchor weight. Abrasion of the suture material at the eyelet had little effect on failure load. Conclusions: At 37°C, structural failure (breaking) of absorbable suture anchors may occur if loaded to the mechanical limit. Absorbable anchors are particularly sensitive to static, long-term loading. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 2 (February), 2003: pp 188–193

Purpose: In the repair of soft tissue to bone using suture anchors, failure of the suture material can occur at the anchor eyelet. This study examines the load strength at which suture material fails with different metallic suture anchor eyelets. Type of study: Biomechanical study. Methods: Suture material (Ethibond No. 2, Ethicon, Norderstedt, Germany) was pulled out from 22 metallic suture anchor models at 60 mm/min, and tensile load at failure and failure mode were recorded. Tests were performed either by simultaneous pulling on 2 suture limbs in 3 different directions (straight, at 45°, and at 45° rotated by 90° to the suture anchor axis) or by pulling on 1 suture limb while measuring the resulting force on the second limb. All tests were performed until suture failure. Pulling was performed in single tests on an Instron materials testing machine (High Wycombe, UK), with the anchors held by a vise. Results: In all cases, the suture failed at the anchor eyelet. Failure load at straight loading ranged from 116 ± 5 N to 226 ± 5 N and from 69 ± 5 N to 193 ± 7 N when loaded at an angle of 45°. The best results were found with the Statak 5.2-mm (Zimmer, Warsaw, IN): 177 N; Corkscrew 6.5-mm anchor (Arthrex, Naples, FL): 174 N; and PeBA 4.0-mm anchor (OBL Orthopaedic Biosystems, Scottsdale, AZ): 169 N. With each eyelet, sutures failed preferentially in 1 direction, depending on the presence of sharp edges. Conclusions: Suture material can be cut at suture anchor eyelets. Failure load depends on sharp edges on the eyelet and occurs at forces up to 73% below the breaking strength of the suture material on a smooth hook. Anchors with suture-protecting channels are particularly sensitive to the orientation in which the sutures are loaded. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 9 (November- December), 2002: pp 1013–1019

Background: Arthroscopic procedures may be technically challenging because of impaired vision, limited space, and the 2-dimensional vision of a 3-dimensional structure. Spatial orientation may get more complicated when the camera is pointing toward the surgeon. Hypothesis: Spatial orientation and arthroscopic performance may be improved by simply mirroring the image on the monitor in different configurations regarding the position and orientation of camera and instrument. Study Design: Descriptive laboratory study. Methods: Thirty volunteers from an orthopaedic department were divided into 3 equal groups according to their arthroscopic experience (beginners, intermediates, seniors). All subjects were asked to perform a standardized task in a closed box mimicking an endoscopic space. The same task had to be performed in 4 different configurations regarding camera and instrument position and orientation (pointing toward or away from the subject) with either the original or mirrored image on the monitor. Efficiency (time per stick; TPS), precision (successful completion of the task), and difficulty rating using a visual analog scale (VAS) were analyzed. Results: Mirroring the image demonstrated no advantage over the original images in any configuration regarding TPS. Successful completion of the task was significantly better when the image was mirrored in the configuration with the camera pointing toward and the instrument away from the surgeon. There was a positive correlation between TPS and subjective VAS difficulty rating ( r = 0.762, P = .000) and a negative correlation between the successful completion of the task and VAS ( r = −0.515, P = .000). Conclusion: Mirroring the image may have a positive effect on arthroscopic performance of surgeons in certain configurations. A significantly improved performance was seen when the arthroscope was pointing toward and the grasping instrument pointing away from the subject. Mirroring the image may facilitate surgery in such clinical situations. Clinical Relevance: Mirroring the image may facilitate arthroscopic procedures in certain clinical situations.

Introduction Early clinical and radiographic diagnosis of failed or loosened anterior cruciate ligament (ACL) reconstructions can be challenging. The aim of the present study is to retrospectively evaluate the use of radiologically visible markers in the ACL graft, serving as a potential diagnostic tool in ACL graft rupture and insufficiency. Methods Twenty patients were included in the study. ACL reconstruction was performed with use of a hamstring autograft in hybrid fixation technique. The graft was marked with two radiodense suture knots, one at the tibial and femoral tunnel openings. Radiographs were performed postoperatively, after 6 weeks and 12 months. Four distances between markers and landmarks were measured in anteroposterior and three in lateral radiographic views and the positional change between the timepoints of measurement was calculated. Results Measurements of the marker distances on radiographs showed an excellent interobserver reliability (κ = 0.97). In two measured distal anteroposterior distances statistically significant changes could be detected between 6 weeks and 12 months postoperatively in one patient with MRI-documented ACL rerupture and in five patients with ACL elongation defined as anteroposterior-translation with side-to-side difference of ≥ 3 mm measured with a Rolimeter device. On lateral radiographs, marker distances were highly variable and did not correlate with clinical ACL elongation. Conclusion The application of radiodense ACL graft markers is a straight-forward, non-expensive and potentially useful diagnostic tool to identify the position of the transplant and for diagnosis of graft elongation or failure. However, the method is sensitive to the radiological projection, which should be further studied and optimized.

No. 5 FiberWire (Arthrex, Naples, FL, USA) cerclage (FWC) and 1.25-mm stainless steel wire cerclage (SSWC) are biomechanically similar in resistance to prosthetic subsidence in shoulder arthroplasty.In this laboratory bench study, 3 different surgical knot configurations (4-throw knot, cow hitch, and simple hitch) using a No. 5 FWC were evaluated and compared with a 1.25-mm SSWC. First, distraction tests were performed using bovine femoral cortical half shells mounted on a testing jig. Cerclage tightening, load to a 3-mm gap opening, and load to total failure were measured. Second, uncemented humeral prosthetic stems were inserted into an experimentally split humeral medullary canal, secured by the cerclage. After 100 N of preloading, the prosthesis was advanced into the humerus at a speed of 0.2 mm/s, and resistance during subsidence up to a penetration depth of 10 mm, as well as gap opening, was measured.Tightening force showed higher values for SSWC (618 N) than FWC (131-137 N) (P.001). Load to total failure was comparable among the 3 different FWC knots (2,642-2,804 N), which were significantly stronger than SSWC (1,775 N, P.001). At 3 mm of distraction, SSWC (1,820 N), cow hitch (1,803 N), and single-throw hitch (1,709 N) performed significantly better than a 4-throw knot (1,289 N) (P.01). Subsidence testing showed no difference in force restraint or gap opening between the best FWC and SSWC.FWCs appear, in vitro, equally suitable to steel wires to stabilize nondisplaced periprosthetic humeral fractures. To actively reduce a displaced fracture, steel wires may still be the first choice.