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Background: A major problem associated with distraction osteogenesis is the long time required for consolidation.Objective: The goal of this study was to determine whether a percutaneous injection of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a Gelfoam carrier would enhance bone consolidation following distraction.Methods: A unilateral tibial osteotomy combined with external stabilization was performed in 14 adult sheep. After a latency of four days, distraction was performed at 1.25 millimetres per day for 20 days. On days 23 and 30, the sheep received an injection of rhBMP-2/Gelfoam or buffer/Gelfoam. During the following 50 days, radiographs and in vivo torsional stiffness measurements were obtained weekly. The effect of rhBMP-2 treatment post-mortem was assessed using destructive biomechanical testing, quantitative CT and DXA analysis.Results: The in vivo stiffness measurements of the sheep treated with rhBMP-2 were significantly higher than those of the carrier control group (p< 0.05). These in vivo data were verified by post-mortem biomechanical testing and quantitative CT analysis. The maximum torsional moment observed was 55% greater in the sheep treated with rhBMP-2.Conclusions: These data support the potential use of rhBMP-2 in an injectable carrier for enhancing consolidation, as it may ultimately lead to shorter treatment times for patients undergoing distraction procedures. [ABSTRACT FROM AUTHOR]

Various types of bone preserving total hip prostheses with a proximal force transmission concept have been developed for younger adults, one of these being the implant "Delfi M®", produced by ESKA until 2009. Since the demand could not meet the expectations, the production was stopped due to economic reasons so that only 31 implants of this type were sold and even less actually implanted. This study followed up 15 Delfi M® prostheses in 12 patients for 3.1 years and represents the only existing valid data about this implant.Demographical, preoperative and postoperative data including clinical scores (HOOS and mHHS) were collected retrospectively. Postoperative X-rays were analyzed by an independent radiologist. One implant had to be exchanged due to an infection and another one due to excessive implant migration. The mHHS and the HOOS scores showed a significant improvement after surgery. In the radiological analysis, there were no signs of radiolucent lines or osteolyses.This trial demonstrates good clinical and radiological midterm results for the Delfi M prosthesis. Limitations of this study are a small sample size and a follow-up time of 3 years at only one timepoint. [ABSTRACT FROM AUTHOR]

Recent studies have assumed micro-fractures of the femoral head during hip resurfacing arthroplasty as a possible reason for fractures at the implant/neck junction. The purpose of this study was to analyze whether implantation of a cementless femoral hip resurfacing component which requires high seating forces, causes micro-fractures of the femoral head. A cementless hip resurfacing femoral component was installed on 20 human, cadaveric femoral heads with an impaction device that generated 4.5 kilonewton force in one group and by hand in the other. Before and after impaction, the specimens were scanned with a μ-CT-System. The CT datasets were segmented and registered for detection of small trabecular fractures. The average percentage of shared voxels was 80.29% (standard deviation 3.24%). Change in bone structure after impaction (19.71%) was found on the surfaces of all samples. No formation that was ascribed to fracture was found. No difference between the specimens that were impacted by hand or by impaction device was noted. No fractures of the cancellous femoral head during installation of a cementless femoral THR component occurred. Cementless hip resurfacing might not increase the risk of fracturing the cancellous femoral head during implantation in a cadaveric μ-CT study. [ABSTRACT FROM AUTHOR]

Osteonecrosis of the femoral head is a more progressive disease for which many patients will eventually require total hip arthroplasty. With the advent of improved metal-on-metal prostheses, total hip resurfacing arthroplasty has emerged as a viable treatment option. However, it remains controversial whether this procedure should be used in patients with osteonecrosis when the femoral resurfacing component is implanted onto non-vital bone. In this study the bone mineral density (BMD) of osteonecrotic femoral heads were compared with the BMD of osteoarthrotic femoral heads. The purpose of this study was to analyse the differences between these two groups to gather information that may be useful in predicting the outcome of total hip resurfacing arthroplasty in cases of severe osteonecrosis of the femoral head. The femoral heads were classified according to the ARCO classification using MRI. For DEXA analysis the femoral heads were subdivided into three regions: the cranial femoral head (R1), the caudal femoral head (R2), and the proximal femoral neck (R3). In R3, BMD in osteonecrotic femoral heads was significantly lower than in those with osteoarthrosis and in R2 it was significantly higher. It can be assumed that a higher BMD in the caudal femoral head (R2) is caused by a "reactive interface" that occurred in this region especially in ARCO IV femoral heads. This fact, the lower BMD in the proximal femoral neck (R3) and the individual expansion of the osteonecrotic region should be considered when planning resurfacing arthroplasty for femoral head necrosis. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to investigate dynamically the load on the cruciate ligaments and the effect of simulated co-contraction of the hamstrings muscles on quadriceps force and load on the cruciate ligaments.Methods: Load transducers were fixed in the fibers of the anterior and posterior cruciate ligament of seven knee specimens. Isokinetic extension motions applying an extension moment of 31 Nm, representing an extension moment capable by healthy human volunteers in isokinetic extension tests, were simulated in a knee simulator from 120° to full knee extension. Quadriceps force and load on the cruciate ligaments were measured in the absence and presence of a 200 N hamstrings co-contraction.Results: Quadriceps force significantly (p = 0.04) increased under the application of hamstrings co-contraction. Anterior cruciate ligament load significantly increased below 20° knee flexion up to 161 N and was significantly (p = 0.04) reduced to 29 N under hamstrings co-contraction at full knee extension. Posterior cruciate ligament load without hamstrings co-contraction showed a maximum load at 112° knee flexion of 38 N, reducing to knee extension and was not significantly increased (p = 0.20) under hamstrings co-contraction, showing a maximum load of 66 N near knee flexion.Conclusions: This dynamic in vitro study revealed the dependency of anterior cruciate ligament load on knee flexion angle during an isokinetic extension cycle. With a co-contraction of hamstring muscles the peak load on the anterior cruciate ligament was significantly decreased in knee extension with a non significant concomitant increase of posterior cruciate load at knee flexion. These findings have implications for graft donor site selection and postoperative rehabilitation, e.g. after anterior cruciate ligament reconstructions. [ABSTRACT FROM AUTHOR]

Background: A short stem hip arthroplasty can be revised in many cases using a conventional stem. Furthermore, in some cases the implantation of a short stem is intended, but intraoperatively reasons may lead to the decision to implant a conventional stem after previous preparation of a short stem., Objective: In both cases it is questionable if the anchorage of a conventional stem is negatively affected by the previous preparation of a short stem. In clinical practice mid- or long-term follow up for these special cases hardly exist., Methods: The strain patterns for the conventional Bicontact stem in primary implantation and after preparation of the proximal femur for a METHA short stem were tested biomechanically in three pairs of cadaveric femora., Results: The strain patterns for the conventional Bicontact after preparation of the METHA short stem were similar to conditions after testing the conventional stem in primary conditions., Conclusions: These data lead to the consequence that in clinical practise the implantation of a conventional stem after preparation of a short stem and even after revision of a short stem is possible without increased risk of loosening or long-term stress-shielding.

Background: Total hip arthroplasty (THA) is one of the most common orthopedic procedures in developed countries, and the high volume of surgery and the socioeconomic burden of failures demand continuous optimization. Operative time has been identified as a significant independent factor influencing the clinical outcome of THA., Objective: The aim of this study was to analyze factors influencing the operative time for THA in a large, single-center cohort., Methods: A consecutive series of 7,674 cases undergoing primary THA was identified, and after multiple imputation of missing values, univariable and multivariable linear regression analyses were performed., Results: In the univariable analysis, all factors showed significant influences on operative time, while multivariable regression analysis revealed that sex, a diagnosis of hip dysplasia and small femoral component size did not reach significance. Younger age, an underlying diagnosis other than osteoarthritis or hip dysplasia, a large stem size, usage of a conventional stem rather than a short stem, a larger cup size and a cemented fixation technique, however, remained significantly influential in terms of a longer operative time., Conclusions: This study identified risk factors for longer operative time that in turn is associated with a higher rate of periprosthetic joint infection and impaired clinical outcome. Our findings could help to refine scheduling of total hip arthroplasty procedures in times of increasing cost and efficiency pressure.

Background: There is currently a lack of consensus regarding the most effective diagnostic algorithm for cases of supposed low-grade infection after total hip arthoplasty (THA)., Objective: The aim of this study was to assess reliability in the use of biopsies, obtained by hip arthroscopy, to detect a periprosthetic hip joint infection (PJI)., Methods: From 2012 to 2016, diagnostic arthroscopy of the hip joint was performed in 20 patients with a supposed PJI following THA. In 10 of these patients, the THA was revised for various reasons after diagnostic arthroscopy. The microbiological and histological findings of the biopsies obtained by arthroscopy were compared to findings from intraoperative samples of the revision arthroplasty., Results: For arthroscopic biopsies, we detected a sensitivity of 1.00 (95% confidence interval [CI] 0.40-1.00), a specificity of 0.83 (95% CI 0.36-1.00), a positive predictive value of 0.80 (95% CI 0.28-1.00), and a negative predictive value of 1.00 (95% CI 0.48-1.00). The accuracy was 0.90., Conclusions: The analysis of arthroscopic biopsies represents a helpful tool to verify or rule out a PJI in selected patients. Nevertheless, minimally invasive diagnostic tools (e.g., laboratory analysis and aspiration) should be utilized beforehand.

Background: Surgical treatment of femoroacetabular impingement is becoming accepted worldwide, owing to improvements in clinical results and quality of life. In addition to treatment by surgical dislocation or arthroscopy, arthroscopic assisted mini-open approach was postulated to treat this pathology., Objective: The aim of this study was to analyze early results of the first consecutive 72 cases of femoroacetabular impingement treated using the arthroscopic assisted mini-open approach in two different centers by two surgeons trained by a senior surgeon experienced in the technique., Methods: Seventy-two consecutive cases of femoroacetabular impingement were operated in arthroscopic assisted mini-open approach technique in two different centers. After a mean follow-up time of 15 months (range 6-24 months), the Western Ontario and McMaster Universities Arthritis Index, Hip disability and Osteoarthritis Outcome Score and University of California, Los Angeles activity score, alpha angle and Wiberg angle were obtained., Results: In both centers, all three scores showed significantly better results at follow-up time than preoperatively. The Western Ontario and McMaster Universities Arthritis Index increased from 64.3 to 91.4 (A) and from 68.1 to 89 (B). The Hip disability and Osteoarthritis Outcome Score increased from 59.5 to 94.4 (A) and from 62.1 to 93.8 (B). The University of California, Los Angeles activity score increased from 5.2 to 8.1 (A) and from 5.3 to 8.4 (B). The alpha angle and the Wiberg angle were significantly reduced after osteoplasty. The overall complication rate was low., Conclusions: Early results of this study show a good clinical and radiological outcome; therefore, the arthroscopic assisted mini-open approach can be used as an alternative in treating femoroacetabular impingement.

Background: Short-stem implants are routinely used for total hip arthroplasty in younger patients that are more likely to have secondary osteoarthritis than older patients., Objective: To investigate the applicability of short-stem hip implants for secondary osteoarthritis due to developmental dysplasia of the hip., Methods: This study analyzed the clinical and radiological results of patients with developmental dysplasia of the hip (DDH, 58 hips) and compared them to those of patients with primary osteoarthritis (POA, 59 hips) treated with the metaphyseal total hip arthroplasty (Metha®) short stem with metaphyseal fixation., Results: The mean clinical and radiological follow-up periods were 2.9 ± 1.1 years and 3.8 ± 1.9 years, respectively. The mean Harris Hip Score (HHS) significantly increased in both groups over this period (p< 0.0001). The caput-collum-diaphysis (CCD) angle was significantly lower in the POA group prior to surgery and significantly increased in the POA and and decreased in DDH groups, respectively. The preoperative femoral offset was lower in the DDH group and increased significantly after surgery., Conclusions: The Metha® short stem in patients with DDH allows good reconstruction of joint biomechanics with a good clinical outcome.

Background: Resurfacing Arthroplasty (RA) of the hip has undergone resurgence with initially mainly good clinical results in young patients. It was mainly performed in younger more active patients with severe symptomatic arthritis of the hip including pelvic deformity. Furthermore the proximal femoral anatomy was preserved for surgical procedures in the future., Objective: The aim of the study was to perform a prospective review of the very first 85 hips that had implantation of one cementless resurfacing system and a mean follow up of 5 years., Methods: 85 cementless Total Hip Resurfacing devices have been performed in 75 patients in our orthopaedic department. The mean age of the study group was 49.8 years. Harries Hip Score, clinical examination data and radiographic parameters including the neck shaft angle (NSA), stem shaft angle (SSA) and detection of radiolucencies were analyzed., Results: Estimated implant survival at five years of follow-up was 88.2% at 5 years follow-up using revision for all causes as the end point. Mean HHS was 92.5 (range 80-100) five years after Resurfacing Arthroplasty., Conclusions: In conclusion we have to admit, that there was a high proportion of failed hip resurfacings but in the proportion that succeeded we saw good clinical results.

Background: Numerous short stemmed total hip arthroplasty (THA) implants have been introduced over the last decades. It is questionable if little differences between the implant designs affect stress shielding and bone remodeling. The finite element analysis allows an evaluation of the design rationale of the implant without negative side effects for the patient., Objective: We investigated a relatively new short stemmed implant designed from clustered CT datasets of proximal femurs. How does the implant affect femoral bone remodeling? Can we see a positive effect on bone remodeling from the CT based design?, Methods: We used a Finite Element Model that was validated by a prospective dual-energy-x-ray-absorptiometry study to calculate apparent bone density., Results: Apparent bone density (ABD) decreased by 2.3% in the entire femur. Bone mass loss was pronounced in the proximal calcar region. Little ABD increase was seen in the lateral aspect of the cortical ring, in the minor trochanter area and at the lateral aspect of the stem., Conclusions: ABD reduction occurs in the proximal regions of the femur. The overall bone mass loss was little after THA with the investigated implant. The specific design seems to have no major effect on stress shielding or load distribution.

Osseointegration of long-term implants is still a problem in orthopaedic surgery. In recent years, several techniques to modify the implant surface to increase bone formation around implants have been described by many authors. Most endoprostheses used in orthopaedic surgery are manufactured from titanium. To understand the process of osseointegration, one has to take into account, that the adhesion of plasma proteins on the surface of titanium implants plays an essential role in the process of implant integration. In the last years, several modifications of implant surfaces (structure, chemistry, surface charge, wettability) have been investigated to improve osseointegration of titanium implants. Furthermore, several cytokines and growth factors have also been suggested to stimulate an implant ingrowth. In this respect, functionalized titanium implant surfaces with bone morphogenetic proteins-2 (BMP-2) as one particular member of the superfamily of transforming growth factor beta (TGF-beta), have proven a potential to stimulate bone formation around implants in different species. In this review the authors provide an overview of surface coatings with BMP-2 and their use in laboratory and experimental settings.

To assess bone healing and investigate the influence of different pharmaceutics (e.g. growth factors) on bone stiffness and strength in-vivo, new quantitative methods are necessary. Therefore, a new manual and motorized stiffness meter to quantify bone regeneration in a model of distraction osteogenesis were compared. The design, equipment, and improvements of the measurement devices are described. Furthermore, their difference in precision and accuracy in comparison to tests from a material testing system, used as "gold standard", were evaluated. Both devices were able to assess regenerate stiffness: the accuracy ranged between +/- 9% for the manual and +/-5% for the motorized version for stiffness data over 0.1 Nm/ degrees; precision between +/- 3.8% for the manual and +/- 3.2% for the motorized device. In summary, the two stiffness measurement devices described in this study have the power to monitor the beginning of bone healing and therefore predict the load bearing capacity of regenerating bone. The motorized version showed advantages over the manual device when investigating and monitoring the stiffness of bone during a consolidation period: (1) better accuracy in both stiffness below and above 0.1 Nm/ degrees, (2) a better precision in the stiffness range of interest, (3) easier handling, and (4) standardisation of the measurement process using the stepper motor and definition of the maximums of torque, angulation and rotation speed.

Today the use of pneumatic tourniquet is commonly accepted in total knee arthroplasty (TKA) to reduce perioperative blood loss. There are a few prospective randomised and nonrandomised studies that compare the effect of tourniquet release timing in cementless or cemented unilateral TKA. However, many of these studies show an inadequate reporting and methodology. This randomized prospective study was designed to investigate the efficiency of tourniquet release timing in preventing perioperative blood loss in a simultaneous bilateral TKA study design. To our knowledge, this is the first study of its kind, in which the effect of tourniquet release timing on perioperative blood loss was investigated in simultaneous bilateral cemented TKA to compare both techniques intraindividually. In 20 patients (40 knees) one knee was operated with tourniquet release and hemostasis before wound closure, and the other knee with tourniquet release after wound closure and pressure dressing. We found no significant difference in total blood loss between both techniques (p=0.930), but a significant difference in operating time (p=0.035). There were no postoperative complications at a follow-up of 6 month. Other studies report an increase the blood loss in early tourniquet release and an increase the risk of early postoperative complications in deflation of tourniquet after wound closure. In this study we found no significant difference in perioperative blood loss and no increase of postoperative complications. Therefore, we recommend a tourniquet release after wound closure to reduce the duration of TKA procedure and to avoid possible risks of extended anaesthesia.

To manage fractures in long bones, intramedullar implants, plates or external fixators are often used. In many cases, the implants are removed after bone consolidation. X-ray images are normally used to monitor bone formation and to determine the point of return to full load bearing and removal of the implants. However, plain radiographs give only inaccurate information about the degree of healing progress. Known quantitative methods as QCT, DEXA, etc. provide information about bone density which certainly contributes to the mechanical properties of healing bone, but they do not provide a direct measurement of the stiffness of the healing callus. In this study we present an in vivo 4-point-bending stiffness device for small animals which is designed to directly monitor the progression of the healing process. The device was tested in a bone-defect model with different test-specimens chosen to simulate the stiffness of bone at different stages of healing. To verify the results, it was tested in an animal fracture study in rabbits during the healing period with and without an intramedulary implant. Both the test-specimen and bones of the in vivo study were compared with data in a materials testing system (MTS) in four-point bending. The device was found to have a high precision and significant in vitro and in vivo correlation with the MTS. The results suggest that this measurement device has the ability to monitor the healing process of bone and to analyse the influence of degradable implants on the mechanical behaviour of bone or bone metabolism effecting pharmaceutics.

In femoral revision arthroplasty the orthopaedic surgeon frequently has to decide between performing an extended trochanteric osteotomy or trying to remove the femoral stem without an osteotomy and taking the risk of an intraoperative fracture. As this decision is often hard to make this study compared intraoperative femoral fractures during stem removal with extended trochanteric osteotomies in femoral revision arthroplasties. Twenty-eight femoral revision arthroplasties with an extended trochanteric osteotomy were compared with forty-five intraoperative fractures during revision hip arthroplasty. Preoperatively and after a follow-up of 2.8 years the patients were examined clinically and radiologically. We found no osteosynthesis related complication in the extended trochanteric osteotomy group, but six in the fracture group. Furthermore fewer re-revisions were observed in the osteotomy group. Additionally, a significant better clinical and radiological outcome can be found in the extended trochanteric osteotomy group compared to the fracture group. The results of this study suggest that a well conducted extended femoral osteotomy should be discussed in special cases to prevent femoral fractures during stem and cement removal which would probably lead to a poor postoperative outcome.

The aim of this study was to evaluate histological and radiological osseointegration characteristics of implanted di-/tri-calciumphosphate in patients bone substitute material in opening-wedge osteotomies patients. Up to now the hypothesis of bioresorption and replacement with vital bone bases on numerous animal studies showing complete remodelling within 12-26 weeks. Histological patient studies hardly exist. In this study 13 patient biopsies were collected 16 months after tibial osteotomy. Unlike animal studies the results showed mainly incorporated avital cement residues (38%) as well as new bone formation (61%). Radiological scoring confirmed increasing signs of osseointegration and an incomplete resorption. In conclusion degradation and replacement of di-/tri-calciumphosphate seems to be less accelerated in patients than prior animal studies indicated. Nevertheless, it shows excellent biocompatibility, good osteoconductive characteristics and may represents a useful alternative to autogenous graft.