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Purpose: We investigated unique tendon growth-factor expression profiles over time in response to simultaneous, similar injuries. Characterizing these genetic differences lays the foundation for creating targeted, tendon-specific therapies and provides insight into why current growth-factor treatments have success in some applications but not others., Methods: The left fourth digital flexor, triceps, and supraspinatus tendons in 24 rats were cut to 50% of their transverse width at the midbelly under anesthesia. On postoperative days 1, 3, 5, 7, and 14, randomly selected rats were sacrificed, and the damaged tendons were excised and flash-frozen in liquid nitrogen. The expressional fibroblast growth factor 1, bone morphogenic protein 13, and transforming growth factor β-1 were measured at each time point and compared to their respective, uninjured levels with real-time polymerase chain reaction., Results: The digital flexor tendon showed exponentially elevated expression of all 3 factors over the preinjury baseline values. Expression in the triceps and supraspinatus had more variation over time. The triceps tendon showed a considerable decrease of transforming growth factor β-1 and bone morphogenic protein 13 expression. The supraspinatus tendon had statistically significant increases of both transforming growth factor β-1 and bone morphogenic protein 13 expression relative to preoperative, uninjured levels, with a nonstatistically significant decrease of fibroblast growth factor 1., Conclusions: Our study suggests different tendons express their own unique growth-factor profiles after similar, simultaneous injuries. The digital flexor showed particularly high, sustained levels of growth-factor expression in comparison to the supraspinatus and triceps, suggesting that variable dosing may be necessary for growth-factor therapies aimed at supplementing innate responses in these different tendon types., Clinical Relevance: These data show different tendons express unique trends of growth-factor expression over time in response to injury, suggesting each unique tendon may require specific dosing or knockdown therapies. These observations serve as a foundation for more tendon-specific questioning, experimentation, and therapeutic design., (© 2022 The Authors.)

Introduction: In-hospital outcomes were compared among patients with shoulder septic arthritis treated with arthrocentesis, open irrigation and débridement, or arthroscopic irrigation and débridement., Methods: The Nationwide Inpatient Sample database was queried for all cases of native shoulder septic arthritis between 2002 and 2011. Patient demographics, comorbidities, and hospitalization complications were compared for the shoulder arthrocentesis (nonsurgical) and open or arthroscopic irrigation and débridement (surgical) groups., Results: Data for 7,145 patients were analyzed. Medical comorbidities and complications were more common in the nonsurgical group than in the open surgical group (septicemia, 36.7% versus 23.6%, P < 0.001; death, 6.5% versus 2.5%, P < 0.001; pneumonia, 11.3% versus 6.2%, P < 0.001; septic shock, 4% versus 2.2%, P < 0.001; and urinary tract infection, 15.5% versus 10.2%, P < 0.001). The mean length of stay was longer in the nonsurgical group compared with the open surgical group (11.5 days versus 10.5 days, respectively; P = 0.002) and the percentage of patients discharged to home was lower (55.1% versus 64.0%, respectively; P < 0.001). Compared with the open surgical group, the arthroscopic surgical group had higher incidences of perioperative septicemia and urinary tract infection and similar average length of stay, hospital charges, and blood transfusion rates, but a lower incidence of osteomyelitis (P < 0.001). In a subgroup of patients with septicemia, Staphylococcus aureus was the most frequently cultured causative organism., Discussion: Septic arthritis in the shoulder is challenging to manage, and patients often have medical comorbidities and complications. In this study, the nonsurgically treated patients had substantially more preexisting comorbidities and in-hospital complications than the surgically treated patients had, which likely contributed to the longer average length of stay and lower discharge percentage in the nonsurgical group., Conclusion: Patients with septic arthritis of the shoulder frequently experience substantial systemic complications regardless of the treatment method. Septicemia was a common complication among all treatment groups, with cultures most frequently indicating Staphylococcus aureus as the causative organism., Level of Evidence: Therapeutic level III.

This article summarizes select multinational early motion protocols. Included are flexor and extensor protocols for digital tendon repair in many forms. Custom orthosis design, exercise regimens, and advanced techniques are examples of what to expect. The goal of the article is to expose the reader to new ideas, educate regarding advanced techniques in tendon rehabilitation, and stimulate independent study to further the reader's skill set., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: The aims of this study were to examine nonrepaired 90% partial lacerations of human cadaver flexor digitorum profundus (FDP) tendon after simulated active motion, and to assess the residual ultimate tensile strength., Methods: Partial, transverse zone II flexor tendon lacerations were made in the volar 90% of the tendon substance in 10 FDP tendons from 5 fresh-frozen human cadaver hands. The tendons were cycled in the curvilinear fashion described by Greenwald 500 times to a tension 25% greater than the maximum in vivo active FDP flexion force measured by Schuind and colleagues. The tendons were then loaded to failure using the same curvilinear model., Results: No tendons ruptured during cycling. Triggering occurred in 3 tendons. All 3 began triggering early in the cycling process, and continued to trigger throughout the remainder of the 500 cycles. The observed triggering mechanics in each case involved the interaction of the proximal face of the lacerated tendon with Camper's chiasm and the pulley edges during extension. The load to failure value of the 90% partially lacerated tendons averaged 141.7 +/- 13 N (mean +/- standard deviation). Tendon failure occurred by delamination of the intact collagen fibers from the distal, discontinuous 90% of the tendon., Conclusions: Cadaveric transverse zone II partial flexor tendon lacerations have residual tensile strength greater than the force required for protected active mobilization., (Copyright 2010. Published by Elsevier Inc.)

Purpose: Osteoarthritis of the trapeziometacarpal (TMC) joint of the thumb affects as many as 25% of postmenopausal women and 5% of middle-aged men. This study investigated the relative contribution of the dorsoradial ligament (DRL) and the deep anterior oblique ligament (dAOL) to the stability of the TMC joint. This knowledge will improve our understanding of the pathomechanics of osteoarthritis at the base of the thumb and may help to design novel reconstructive surgical procedures., Methods: Seventeen intact cadaver hands were dissected to reveal the DRL and dAOL. Either the DRL or dAOL was transected randomly, physiologic muscle loads were applied to simulate lateral key pinch or thumb opposition, or a 3-dimensional magnetic tracking system was used to record the position of the thumb metacarpal relative to the trapezium. The differences in the 3-dimensional positions between the control and transected states were determined., Results: In lateral pinch, transection of the DRL resulted in a mean increased 3-dimensional translation of 1.3 mm, whereas transection of the dAOL resulted in a mean increased 3-dimensional translation of 0.6 mm. Statistically significant 2-dimensional findings in lateral pinch after transecting the DRL or dAOL included an increased palmar subluxation of 0.3 mm and 0.2 mm, an increased radial (1.0 mm) and ulnar (0.3 mm) translation, and an increased pronation of 4.1 degrees and 2.4 degrees, respectively. In thumb opposition, transection of the DRL resulted in a mean increased 3-dimensional translation of 1.0 mm, whereas transection of the dAOL resulted in a mean increased 3-dimensional translation of 0.5 mm., Conclusions: In most degrees of freedom of metacarpal movement relative to the trapezium, the DRL is relatively more important than the dAOL in providing stability to the TMC joint.

Purpose: Coronoid injuries are classified according to the size of the coronoid fracture. The purpose of this study was to provide a detailed anatomic description of the coronoid process, with specific focus on the coronoid height, the coronoid width, and the olecranon-coronoid angle., Methods: Thirty-five cadaveric arms were dissected. All soft tissue was removed and the ulna was disarticulated from the humerus, radius, and the carpal bones. A 3-dimensional digitizing system was used to locate 19 anatomic landmarks on each specimen. By using the 3-dimensional coordinates of the landmarks, the coronoid heights, proximal ulnar widths, and olecranon-coronoid angles were determined., Results: The coronoid height, with its base defined by the trough of the trochlear notch and the slope change of the distal coronoid process, measured 15 mm and was 42% of the ulnar height. The coronoid height, with its base defined by the transverse groove of the sigmoid notch at the guiding ridge and the distal insertion of the brachialis muscle, measured 15 mm and was 43% of the ulnar height. The olecranon-coronoid angle ranged between 33 degrees and 38 degrees ., Conclusions: For lateral radiographic classification of coronoid fractures, coronoid height is best defined by the trough of the trochlear notch and the slope change of the distal coronoid process. For anatomic studies, coronoid height is best defined by the transverse groove of the sigmoid notch at the guiding ridge and the distal insertion of the brachialis muscle. The olecranon-coronoid angle is best defined by the angle formed by the lines from the olecranon tip through the coronoid tip and through the slope change of the distal coronoid process. The coronoid anatomy measurements reported in this study may help to improve coronoid fracture classification.

Zone I flexor tendon injuries entail injuries to the flexor digitorum profundus (FDP) tendon. These injuries occur distal to the superficialis insertion over the middle phalanx or proximal distal phalanx, and as such are isolated injuries to the FDP. The mechanism most commonly is closed avulsion from the distal phalanx or a laceration, but other mechanisms such as open avulsion or crush injury can occur. On physical examination, the cascade of the fingers will be disrupted, and distal interphalangeal (DIP) joint flexion must be isolated to determine if the FDP tendon is continuous, as other mechanisms are present to enable finger flexion at the other joints.

Clinical outcomes following flexor tendon repair have made significant improvements in the last 50 years. In that time standard treatment has evolved from secondary grafting to primary repair with postoperative rehabilitation protocols. Unfortunately, excellent results are not yet attained universally following treatment. Improving understanding of tendon healing at the cellular, molecular, and genetic levels will likely enable surgeons to modulate the normal repair process. We now look toward biologic augmentation of flexor tendon repairs to address the problems of increasing tensile strength while reducing adhesion formation following injury and operative repair.

Flexor tendon repair in zone II is still a technically demanding procedure, but the outcomes have become more predictable and satisfying. Of keystone importance for obtaining the goals of normal strength and gliding of repaired flexor tendons are an atraumatic surgical technique, an appropriate suture material, a competent pulley system, and the use of early motion rehabilitation protocols. The overall goal of hand and finger function also implies timely addressing of neurovascular injuries. New devices such as the TenoFix (Ortheon Medical; Winter Park, Florida) have shown adequate strength in the laboratory but are bulky and untested for work of flexion. Insufficient clinical data and high cost may prevent widespread use.

Purpose: To compare the maximum tensile load, change in work of flexion, and gapping at the repair site after zone II flexor digitorum profundus tendon repairs using 2-0, 3-0, and 4-0 braided polyester 4-strand locked cruciate repair technique in fresh-frozen cadaveric hands with standard 6-0 suture epitenon repairs, to determine which suture size is the best for a core repair., Methods: A randomized study was designed using 41 tendons from 15 fresh-frozen cadaveric hands. We included only the flexor digitorum profundus tendons from the index, middle, and ring fingers to minimize variation between digits. Core suture size was randomized for each finger. A sharp laceration through the flexor digitorum profundus in zone II was made and a 4-strand locked cruciate braided polyester core stitch was performed along with a locked epitenon stitch. Cyclic loading was performed for 1,000 cycles. For each tendon the mean work of flexion (before/after zone II repair) and maximum tensile load were measured using a custom-designed tensiometer, as was gapping before maximum tensile loading., Results: Mean gaps after 1,000 load-unload cycles to 3.9 N of pulp pinch did not approach the clinically significant limit of 3 mm in each group. By using a regression model, we found that the prerepair and postrepair comparisons for mean work of flexion to a 3.9-N pulp pinch showed the greatest change in work of flexion for 2-0 braided polyester. Statistical significance was found between 2-0 braided polyester and 3-0 or 4-0 braided polyester; however, the work of flexion between the 3-0 and 4-0 polyester was not clinically significant. The highest maximum tensile load was obtained with suture size 2-0 braided polyester. The maximal tensile load statistically showed 2-0 braided polyester to be stronger than 4-0 braided polyester but we found no statistically significant difference between 3-0 and 2-0 braided polyester or between 3-0 and 4-0 braided polyester., Conclusions: In this cadaveric study we found that increasing locking cruciate suture caliber from 4-0 to 2-0 increased maximum tensile strength but also caused increased work of flexion. Gapping was not affected by suture caliber. There was no significant difference in strength or mean change in work of flexion between 3-0 or 4-0 braided polyester sutures.

Purpose: Adenoviral vector-based gene therapy is a promising technique for the delivery of growth factors to tendons. The objective of this study was to determine whether rabbit flexor tendons could be transduced effectively by adenoviral vectors and whether the introduction of adenoviral vectors would cause a notable local inflammatory response., Methods: Recombinant adenoviruses expressing green fluorescent protein (AdGFP) or BMP-13 (AdBMP-13) were constructed and 3 different viral titers (1 x 10(7), 1 x 10(8), and 1 x 10(9)) were tested in this study. The second through fifth tendons of the forepaws and hindpaws of a New Zealand white rabbit were identified surgically and injected with different viral titers of adenoviruses. The fifth tendon was used as a control. The tendons were harvested 12 days after surgery. The retrieved tendons were sectioned to measure transgene expression, as well as for histologic evaluation., Results: At all tested viral titers an efficient dose-dependent transgene expression was detected in all samples at 12 days after injection. At the highest dose the injection sites were notable for lymphocytic infiltration, suggesting that injected adenoviral vectors can illicit some local inflammatory response. Lymphocytic infiltration was much less apparent, however, in the tendons injected with lower titers of adenoviral vectors. There was no evidence of a massive inflammatory response and/or cell death., Conclusions: Our findings show that adenovirus-based gene therapy is an efficient means of gene delivery to rabbit flexor tendons. Transduction efficiency of transgenes was dose dependent across the tested titers, although adenovirus-induced inflammation was notable only at the highest titer. This indicates that efficient gene transfer without notable local inflammatory response may be achieved by using the lower titers. Although adenovirus-induced inflammation can be minimized by using lower viral titers, its impact on adhesion formation in the long term remains unknown.

Purpose: The intrinsic muscles and ulnar capsuloligamentous structures (UCLS), which consist of the ulnar collateral ligament (UCL), accessory UCL, dorsal capsule, and volar plate of the thumb metacarpophalangeal (MCP) joint are important for controlling the motion and stability of the MCP joint during pinch. The purpose of this cadaveric study was to determine the effects of the adductor pollicis (AdP) and abductor pollicis brevis (APB) on the 3-dimensional MCP joint laxity before transection of the UCLS and after reconstruction of the UCL and repair of the dorsal capsule., Methods: Loads were applied to the flexor pollicis longus (FPL) alone, to the AdP and FPL in combination, and to the APB and FPL in combination in 11 cadavers. This was done in the intact joint after the UCLS were transected and after the UCL was reconstructed for flexion angles of 0 degrees, 15 degrees, 30 degrees, and 45 degrees. The spatial positions of the proximal phalanx and the metacarpal of the MCP joint were measured with a 6-degrees-of-freedom digitizing system., Results: In the intact joint combined loading of the AdP and FPL did not affect the position of the proximal phalanx. Combined loading of the APB and FPL changed the position of the phalanx from an ulnar to a radial shift and from an ulnar to a radial deviation and it increased pronation. After transection of the UCLS combined loading of the FPL and AdP increased supination of the MCP joint and combined loading of the FPL and APB increased radial shift, radial deviation, and pronation of the joint. Reconstruction of the UCL restored normal laxity to the MCP joint., Conclusions: The AdP failed to affect MCP joint motion. The ABP produced a radial shift and radial deviation of the MCP joint and increased pronation of the thumb. Transection of the UCLS increased joint laxity for each of the combined loadings and reconstruction of the UCL restored normal laxity to the MCP joint.

Early active motion limits adhesion formation and thus improves functional performance after tendon grafting. The early strength of distal fixation is critical to successful tendon grafting. We describe a new Y-tunnel technique of distal fixation and compare it with 2 established methods, the Pulvertaft transverse tunnel and the Bunnell button over the fingernail techniques, in a human cadaver model to determine which is the strongest method. Hands with a grafted tendon were rigidly mounted on an anatomic tensiometer testing apparatus and loaded to failure. Mean load to failure (newtons +/- 95% confidence intervals) of the Y-tunnel technique (155.2 +/- 29.4) was greater than those for the Pulvertaft (100.2 +/- 13.2) and Bunnell (57.1 +/- 4.7) techniques. Two-way analysis of variance showed significant differences, and the Bonferroni multiple pairwise comparison test showed that all 3 intergroup comparisons were statistically significant. These results indicate marked improvement in immediate strength with the Y-tunnel technique and lay the groundwork for further studies using a healing tendon model.

To compare the biomechanical performances of six 4-strand flexor tendon repairs at zone II, we used an in situ testing model in 54 cadaver profundus tendons. The techniques studied were the modified Becker, modified double Tsuge, Lee, locked cruciate, Robertson, and Strickland. Prerepair and postrepair comparisons for work of flexion to a 3.9-N pulp pinch (equal to 12.6 N tendon force) showed the greatest interference to gliding in the modified Becker repair and the least in the modified double Tsuge repair. Mean gaps after 1,000 load-unload cycles to a 3.9-N pulp pinch did not approach the clinically important limit of 3 mm in all groups. Ultimate tensile strength was highest in the modified Becker (69.4 +/- 8.2 N) but not significantly higher than the modified double Tsuge (60.3 +/-15.3 N) and locked cruciate (64.1 +/- 16.2 N). In all repair groups the mean pulp pinch forces upon failure were well above values recommended for active mobilization protocols that use external load guides. The locked cruciate, modified double Tsuge, and modified Becker repairs were strong enough for an early active motion protocol after surgery. Locked cruciate and modified double Tsuge were easier to perform and provided less interference to tendon gliding than the modified Becker repair.

The relative strengths of 4 methods for repair of the flexor digitorum superficialis tendon were examined in 14 fresh-frozen cadaver hands (40 tendons). All tendons underwent sharp zone II transection at Camper's chiasma. All transections were repaired with 4.0 Ethibond (Ethicon Inc, Sommerville, NJ) using modified Becker, modified Kessler, horizontal mattress, or simple sutures. Flexion of the repaired digit at a constant excursion rate was rendered up to tendon rupture. The modified Becker technique withstood breaking forces (57.9 N) significantly greater than the other techniques examined. Forces up to 34 N have been measured in vivo during unresisted active finger motion. Thus, the modified Becker technique appears to provide adequate strength for early active flexor digitorum superficialis motion.

Kessler, Strickland, or modified Becker repairs, all augmented with a running circumferential epitenon suture, were performed for simulated zone II flexor tendon lacerations in the index, long, and ring fingers of 12 fresh-frozen cadaveric specimens. Each hand was tested with a tensiometer built for curvilinear testing of human flexor tendons in an intact hand. Each tendon was cycled 100 times, then examined for gapping before testing to failure. Maximum load to failure, including tendon load and pinch force, was recorded for each tendon. We propose that combining the advantages of cyclical testing and a curvilinear model is the most effective way of testing flexor tendon repairs capable of undergoing an early active motion protocol. None of the repaired tendons failed during the cyclic portion of testing. The average gapping after cycling for the 3 suture techniques was 0.12 +/- 0.35 mm for the Kessler technique, 0. 00 +/- 0.00 mm for the Strickland technique, and 0.19 +/- 0.26 mm for the modified Becker technique. The maximum tendon loads to failure were 33.8 +/- 6.8 N for the Kessler technique, 30.4 +/- 5.64 N for the Strickland technique, and 76.3 +/- 9.02 N for the modified Becker technique. There was a statistically significant difference between the modified Becker repair and the other 2 repairs for maximum tendon load and pinch force to failure. The results of this study show that all 3 tendon repair techniques can withstand forces reported with passive motion, but only the modified Becker repair allows sufficient strength above those forces that are estimated for active motion during tendon healing.

Twenty fresh frozen hand specimens from cadavers were studied. Physiologic levels of extrinsic muscle loads were applied to the extrinsic flexor tendons of the index finger to simulate tip pinch of the finger on a fixed plate. The acute effects of transection of the radial collateral ligament and accessory radial collateral ligament (radial collateral ligament complex) with and without transection of the dorsal capsule and volar plate on the position of the proximal phalanx with respect to the metacarpal bone of the index finger were investigated. The acute effects of reconstruction of the radial collateral ligament, for each of two different surgical techniques, on the position of the proximal phalanx also were investigated. The spatial positions of the metacarpal bone and proximal phalanx were measured with a six-degree-of-freedom digitizing system for flexion angles from 0 degrees to 90 degrees in increments of 15 degrees. Transection of the radial collateral ligament complex resulted in significant increases in ulnar deviation (adduction) of the proximal phalanx and in volar translation. Additional transection of the dorsal capsule and volar plate caused significant increases in ulnar deviation, pronation, volar translation, and ulnar shift. The first surgical technique, one traditionally used to reconstruct the metacarpophalangeal joint of the thumb, failed to return the three-dimensional position of the proximal phalanx on the metacarpal head of the index finger to normal. The second surgical technique, based on anatomy, returned the position of the proximal phalanx to levels not statistically different from normal for most flexion angles.

This article reports the first randomized prospective multicenter evaluation of a bioabsorbable conduit for nerve repair. The study enrolled 98 subjects with 136 nerve transections in the hand and prospectively randomized the repair to two groups: standard repair, either end-to-end or with a nerve graft, or repair using a polyglycolic acid conduit. Two-point discrimination was measured by a blinded observer at 3, 6, 9, and 12 months after repair. There were 56 nerves repaired in the control group and 46 nerves repaired with a conduit available for follow-up. Three patients had a partial conduit extrusion as a result of loss of the initially crushed skin flap. The overall results showed no significant difference between the two groups as a whole. In the control group, excellent results were obtained in 43 percent of repairs, good results in 43 percent, and poor results in 14 percent. In those nerves repaired with a conduit, excellent results were obtained in 44 percent, good results in 30 percent, and poor results in 26 percent (p = 0.46). When the sensory recovery was examined with regard to length of nerve gap, however, nerves with gaps of 4 mm or less had better sensation when repaired with a conduit; the mean moving two-point discrimination was 3.7 +/- 1.4 mm for polyglycolic acid tube repair and 6.1 +/- 3.3 mm for end-to-end repairs (p = 0.03). All injured nerves with deficits of 8 mm or greater were reconstructed with either a nerve graft or a conduit. This subgroup also demonstrated a significant difference in favor of the polyglycolic acid tube. The mean moving two-point discrimination for the conduit was 6.8 +/- 3.8 mm, with excellent results obtained in 7 of 17 nerves, whereas the mean moving two-point discrimination for the graft repair was 12.9 +/- 2.4 mm, with excellent results obtained in none of the eight nerves (p < 0.001 and p = 0.06, respectively). This investigation demonstrates improved sensation when a conduit repair is used for nerve gaps of 4 mm or less, compared with end-to-end repair of digital nerves. Polyglycolic acid conduit repair also produces results superior to those of a nerve graft for larger nerve gaps and eliminates the donor-site morbidity associated with nerve-graft harvesting.

Injuries to the ulnar collateral ligament (UCL) of the metacarpophalangeal joint of the thumb are common and may result in functional instability of the joint. Eight cadaveric hands were studied. Physiologic levels of muscle loads were applied to the extrinsic flexor tendon of the thumb to simulate tip pinch of the thumb. We investigated the effects of transection of the UCL and accessory UCL (UCL complex) with and without transection of the dorsal capsule and volar plate and of reconstruction of the UCL, for 2 surgical techniques, on the position of the proximal phalanx with respect to the thumb metacarpal. The spatial positions of the metacarpal and proximal phalanx were measured with a 6 degrees of freedom digitizing system for flexion angles from 0 degrees to 60 degrees in 15 degrees increments. Transection of the UCL complex, dorsal capsule, and volar plate (ulnar capsuloligamentous structures) of the metacarpophalangeal joint did not affect radioulnar deviation or radioulnar shift, but did produce significant increases in supination by 8 degrees and volar translation by 2 mm at 45 degrees and 60 degrees compared with those found for the intact joint. The UCL was reconstructed with a tendon graft using the autogenous extensor digiti quinti. The first surgical technique, a traditional technique, and the second surgical technique, a technique based on anatomy, returned the position of the proximal phalanx on the metacarpal head to normal, with the exceptions of volar translation of the proximal phalanx at 60 degrees and trends toward abnormal supination of the proximal phalanx for flexion angels of 45 degrees and 60 degrees., (Copyright 2000 by the American Society for Surgery of the Hand.)

Many clinical studies have demonstrated that in the conservative care of boxer's fractures (casting, with or without reduction), between 20 degrees and 70 degrees of dorsal angulation is acceptable. This biomechanical study characterized how boxer's fracture angulation affects the ability of the intrinsic muscles to initiate grip. The flexor digiti minimi and third volar interosseous were modeled in this study. Muscular excursion of the intrinsics were modeled with a cable and sheath device. Metacarpophalangeal joint flexion per unit excursion curves were collected when the metacarpal neck was at a fracture angle of 0 degree, 15 degrees, 30 degrees, 45 degrees, 60 degrees, and 75 degrees . As fracture angles increased, the distance between the origin and insertion of the flexor digiti minimi decreased, creating shortening, or slack, of the modeled muscle. Slack was defined as excursion generating no joint flexion. Muscle shortening data were integrated with Jacobsen's muscle fiber length data and Elftmann's fiber length/tension relationship to estimate how the fracture angle affects the initiation of metacarpophalangeal joint flexion and the strength of grip. According to this model's data, fracture angles of up to 30 degrees are compatible with nearly normal mechanics. A 30 degrees angulation is associated with a flexor digiti minimi grip strength of 92% maximum and preserves 78% of the intact finger's range of motion. We therefore conclude that 30 degrees is the upper limit for acceptable final angulation.

To study the effect of dorsally placed flexor tendon repairs on human cadaver tendons, we used the Kessler, Strickland, Robertson, and modified Becker techniques. The strengths of the repairs were tested in a previously described human cadaveric curvilinear model. There were statistically significant increases in dorsal versus volar grasping strength with the Kessler repair (38 N vs 33 N) and the Robertson repair (51 N vs 43 N). There were no differences with the locking Strickland and modified Becker repairs. One may infer that the locking techniques are intrinsically tighter and may not be as susceptible to the different forces between the tensile and compressive surfaces of a dynamic flexor tendon.

Komanduri et al showed that dorsal tendon repairs using Kessler and Bunnell techniques were stronger than the standard volar repair (J Hand Surg 1996;21 A:605-611). They concluded that when testing in the anatomic curvilinear mode, the differences in strength were due to tension banding. Soejima et al challenged that concept by stating that the difference in strength was in the biomechanics of the dorsal tendon itself (J Hand Surg 1995;20A:801-807). We set out to confirm Soejima et al's theory by using more core suture techniques. We compared the tensile strength at 2-mm gap and the ultimate tensile strength of Kessler, Strickland, Robertson, and modified Becker sutures. Ten repairs of each suture type were placed either dorsally or volarly in matched human cadaver flexor tendons. There was no statistical difference between volar and dorsal placement for either maximum tensile force or force at 2-mm gap. Our study does not confirm Soejima et al's in any of the four suturing techniques.

Many reports have been devoted to characterizing the significance of the pulleys for the flexor digitorum profundus (FDP). However, no comparable work has been published on the flexor digitorum superficialis (FDS). This study characterized the FDS in a human cadaver model. Eleven fresh-frozen cadaver hands were used. By using a tensiometer, data were gathered for tendon excursion, tendon load, and work of flexion. Changes in efficiency were caused by excision of annular pulleys A1, A2, A3, and the palmar aponeurotic pulley. We also measured the effect of FDP excision on FDS efficiency. Sectioning of the A2 and A3 pulleys together caused statistically significant losses of efficiency in all three parameters (work, load, and excursion). When the FDP was removed from a finger with an intact pulley system, losses in both work and excursion efficiencies were significant. Removing the FDP while cutting different pulleys caused significant decrease in FDS excursion efficiency. We conclude that A2 and A3 are the most important pulleys for maintaining normal FDS function, and that the presence of the FDP in the digital sheath is essential for optimal FDS excursion efficiency.

This study was designed to investigate whether the position of the wrist or sectioning of the transverse carpal ligament (TCL), as well as the palmar fascia and forearm fascia, modifies the biomechanical behavior of the finger flexion, as defined by changes of excursion, load (force), and work of the flexor tendons. The parameters were measured in fresh-frozen cadaver hands with the wrist in 30 degree extension, neutral, and 30 degree flexion, before and after division of the TCL. Having the wrist in extension improved excursion efficiency, whereas flexing the wrist produced the opposite effect, with a 16% decrease in excursion efficiency after division of the TCL. Change in excursion efficiency between the intact and cut TCL was 8% in the flexed position, 5% in the neutral position, and 0.3% in the extended position. Change in load efficiency between intact and cut TCL was 11% in the flexed position, 6% in the neutral position, and 0% in the extended position. Change in the work efficiency between intact and cut TCL groups was noted most with the wrist in the flexed position (13%), compared to a small change (3%) in neutral wrist position and no change in wrist extension. A significant decrease in the excursion efficiency of the flexor tendons was demonstrated when the wrist was in the flexed position. Any increase in the excursion of the flexor tendons could clinically result in decreased grip strength when the wrist is flexed. Furthermore, the effects of TCL division were not significant when wrist position was in extension.

Twenty-six fresh-frozen cadaver hands (78 tendons) underwent sharp zone II profundus tendon transection and repair with Bunnell, Kessler, Kessler with circumferential epitenon, or epitenon-alone sutures. Suture assignment was randomized, and core sutures were placed either palmarly or dorsally (also randomized) within the flexor tendon. Ten trials of each suture type and placement were performed. Flexion of the repaired digit at a constant excursion rate was performed up to tendon rupture. In all cases, dorsally placed sutures provided significantly more tensile strength than palmarly placed sutures. In light of the previous evidence that tendon viability is dependent on diffusion and not dependent on the vascular supply, we believe that a dorsally placed core suture and circumferential epitenon repair for zone II profundus repairs should be considered because of their increased strength. All future testing of tendon repairs should be performed in an anatomic "curvilinear" model because it simulates the specific biomechanical conditions that are unique to the flexing digit.

Anatomy texts describe the flexor synovial sheath of the little finger as extending proximally into the palm to join with the ulnar bursa in 80% of cases. Based on this, one would expect frequent extension of little finger flexor synovial sheath infections into the forearm. Methylene blue injection followed by open tenogram was used to define the anatomy of the flexor synovial sheath of the little finger in 60 cadaver hands. In 27 hands, the flexor synovial sheath extended proximally from the bony profundus tendon insertion to terminate at the palmar aponeurosis pulley. A stricture of varying length separated the flexor synovial sheath from the more proximal ulnar bursa. In 19 hands, the flexor synovial sheath was continuous with the ulnar bursa, conforming to the conventional textbook description. In 14 hands, the flexor synovial sheath stopped at the proximal border of the A1 pulley. An inconsistent defect from 1 to 10 mm was noted. The clinical implications of these findings suggest that many little finger flexor synovial sheath infections, when caught early and after careful physical examination, need only be managed by drainage at the distal palmar level.

Segments of rabbit flexor profundus tendon were transected at their zone II midpoints. Before reapproximation, proximal and/or distal segment halves received 10,000 rads of x-radiation. Four treatment groups were examined with light and electron microscopy after 2, 4, and 8 weeks in culture: group XX had proximal and distal tendon halves irradiated, group PX had only distal tendon halves irradiated, group XD had only proximal tendon halves irradiated, and group PD served as nonirradiated control tendons. After 2 weeks, the epitenons of all nonirradiated segments had proliferated to become several cell layers thick with migratory-type cells. By 4 weeks these cells in groups PX and XD crossed the repair site and invaded the opposing irradiated segments in a previously undescribed pattern. By 8 weeks, bridging and remodeling of the repair site were evident in groups PX and XD, yet not to the extent noted in the nonirradiated control group PD. No histologically evident difference in mechanism or completeness of healing was observed between groups PX and XD, and no comparable proliferation, bridging, or remodeling was observed in the completely irradiated group XX. These observations allowed for conclusions to be drawn regarding regional involvement during intrinsic tendon healing and confirmed the pluripotency of poorly differentiated epitenocytes.

The biomechanical effects of constant mechanical load on tendon repair in vitro were determined for rabbit flexor tendons. Tendons were removed from Zone II, transected, reapproximated with four simple sutures, and cultured in standard medium. Tendons from the right forelimbs were loaded with 3.1-g weights; tendons from the contralateral forelimbs served as unloaded tendons. Tenorrhaphies were disrupted at zero, one, three, and six weeks postsuturing by fixed-speed tensiometry. True maximum stress (strength), normalized energy absorbed, and tangent modulus steadily increased over time, becoming significantly greater than unincubated controls in the loaded and unloaded groups at six weeks. True strain at maximum stress increased with duration for unloaded tendons; after six weeks it was significantly greater than unincubated control tendons. This study demonstrates a method for quantifying the biomechanics of tendon after intrinsic tendon segment healing and presents the first biomechanical evaluation of constant tension applied across the laceration site during an in vitro healing phase.

We performed an in-depth biomechanical evaluation of the effect of hyaluronic acid (HA) on the healing of rabbit profundus tendons cultured in vitro. Seventy-eight flexor tendons from 13 rabbits were transected and reapproximated at their Zone II midpoints. Tendons were divided into left and right forepaw groups. Each tendon from the left forepaw group was incubated in one of four possible culture media: control (no HA), low (0.1 mg/ml), medium (0.5 mg/ml), or high (1.0 mg/ml) HA media. HA was added on the first day of incubation. Each tendon from the right forepaw group was cultured in low, medium, or high concentrations of HA, but HA was added after 1 week of incubation in control media. All tendons were cultured for 8 weeks, after which time tenorrhaphies were disrupted and the following biomechanical parameters were determined: apparent maximum stress, apparent strain at apparent maximum stress, normalized energy absorption, and tangent modulus before failure. Comparisons using these parameters showed no statistically significant differences among the various tendon groups. We believe this is the first study of its kind to show no effect of hyaluronic acid on the functional strength of tendon after healing in vitro.

This study was designed to evaluate biomechanically defined wound healing in full-thickness skin explants in tissue culture. The requirement for preculture incubation of wounds in situ was characterized. Full-thickness skin incisions were made in 44 rats and closed immediately. Wounds were incubated in situ for 0, 12, 24, 36, 48, 72, or 96 hours before harvesting and placement into tissue culture media for 6 weeks. Healing was evaluated by biomechanical criteria: tensiometric distraction to wound rupture generated true stress and energy absorption data. Burst-strength (maximum true stress) and toughness (energy absorption) were five times higher in the 48-hour group than in any other group; other groups were not different from each other. This study demonstrates long-term survival of full-thickness skin in culture and shows that full-thickness skin explants heal in tissue culture. Possible explanations for the narrow window of opportunity for harvest (48 hours, no more and no less) are discussed.

We performed in-vitro microelectrode studies on the anconeus muscle of 14 patients with diseases of neuromuscular transmission. The procedure detected marked abnormalities in all patients studied, and may therefore be a valuable technique for the study of human disorders of neuromuscular transmission.

Ten patients with true aneurysmal disease of the hand and forearm vessels were treated at our institution between 1981 and 1990. Pseudoaneurysms resulting from penetrating trauma or mycotic aneurysms were specifically excluded. Eight patients were male, two were female; mean patient age was 38 years (range 26 to 72 years). A history of repetitive occupational or recreational trauma was elicited in five patients. All patients presented with painful masses or neurologic symptoms due to nerve compression. Ischemic changes were evident in five patients due to thrombosis or distal embolization. Arteriography and transcutaneous Doppler ultrasound aided in documentation of flow characteristics and planning for operative intervention. Three patients underwent excision and ligation once collateral flow was demonstrated to be adequate and reconstruction was not felt to be feasible. Seven patients underwent resection with vein graft reconstruction. Immediate postoperative and interval patency rates were 100%. No digital amputations were required even in those patients presenting with severe distal ischemia.

The intrinsic capability of the human superficialis flexor tendon to heal a reapproximated laceration site in vitro was examined. Segments of lacerated and sutured human superficialis flexor tendons from zone II were cultured for two, four, or eight weeks in vitro and analyzed by use of light and electron microscopy. We noted a specific pattern of intrinsic healing at the repair site during the incubation period. After two weeks, the cells of the epitenon from both tendon stumps proliferated and appeared to migrate into the repair site. Elongated cells of the thickened epitenon bridged the laceration and synthesized new collagen fibers. By eight weeks, a smooth contiguous tendon surface was restored and the internal collagen bundles were brought into intimate contact. The fibroblasts bridging the laceration, both in the epitenon and centrally in the repair site, were oriented perpendicular to the cut surfaces. The cells in the repair site were active in protein synthesis, and new collagen fibers were present. No cellular necrosis was observed in the internal repair site. Our results indicate that human superficialis tendons possess an intrinsic capacity to heal with diffusion and without dependence on extratendinous cells or on adhesions.

We analyzed the healing capability of the human superficialis (sublimus) flexor tendon in response to injury in vitro by performing a morphologic study of tendon repair. Tendon segments were cultured in cell-free medium for 2, 4, or 8 weeks, and the cut-end repair sites were compared with those in fresh control segments on light and electron microscopy. Tendon encapsulation had occurred at 2 weeks, by the proliferation and migration of elongated fibroblasts from the epitenon and from collagen bundles of the endotenon to cover the surface of the cut tendon ends. As migrating epitenon cells approached the cut margin, they consistently shifted from a parallel to a circumferential orientation with respect to the tendon axis. By 4 weeks, the encapsulating surface cells had lost their membranous ruffles and had become flattened. Within the capsule, phagocytic cells engulfed collagen debris, and fibroblasts containing extensive rough endoplasmic reticulum profiles and secretory vesicles participated in protein synthesis. The surface of the capsule was smooth and, at 8 weeks, was almost indistinguishable from the epitenon surface of uncultured controls. The capsule now had a collagen-synthesizing layer of fibroblasts superimposed on layers of maturing collagen bundles that separated resting-phase fibroblasts. These findings demonstrate that segments of human superficialis flexor tendons participate in an intrinsic repair response without contributions from extrinsic cells.

Two young women developed septic arthritis in an interphalangeal joint following a seal bite. One patient was cured with tetracycline: the other required joint arthrodesis. This entity known as "seal finger" is common among sealers. Although the infection may be cured with tetracycline, in late treated or untreated cases joint destruction may occur. No causative organism has been isolated.

We retrospectively reviewed the cases of eight patients with histiocytic lymphoma (reticulum-cell sarcoma) appearing as a primary bone lesion. Histological findings were classified according to the criteria of Rappaport. Lesions were staged as suggested by the Ann Arbor Conference. After thorough staging, four of the eight patients were shown to have more extensive disease than was initially thought, which altered the therapeutic approach used. Thorough staging is necessary for improved survival of patients with histiocytic lymphoma of bone. We suggest a diagnostic strategy for patients with histiocytic lymphoma presenting in bone that leads to appropriate therapy.

Painful neuromas in the hand are not only very disabling for the patient, but difficult to treat. We present the results of 20 painful neuromas treated by burying the neuroma in the bone. Eighteen of the 20 neuromas operated on had acceptable results, according to the criteria of Herndon et al. We present our technique and compare our results with other treatments in the literature.

This work demonstrates that human flexor tendon segments have the same capabilities to survive culturing and to mobilize an intrinsic healing response as previously described animal models. Segments of human flexor profundus tendons from the flexor tendon sheath were cultured in vitro and analyzed at 1, 2, and 4 weeks by scanning and transmission electron microscopy. The epitenon area thickened during the first week of culture. Fibroblasts migrated over the cut surface of the collagen bundles until they encapsulated the cut end by the second week when new collagen fibrils were seen in the extracellular spaces. By the fourth week, cells in multiple layers covered the cut end of the tendon, both collagen fibrils and new mature collagen bundles were seen. End encapsulation was accomplished by fibroblasts migrating from the outer surface and the interstices of the tendon. The encapsulating cells were active in phagocytosis and collagen synthesis during the entire incubation period.

The intrinsic capacity of tendons to heal in response to injury has recently been demonstrated by many investigators. Electrical stimulation is often assumed to augment regeneration of various tissues. Using newly developed methods of whole-tendon culture, the authors examined the effect of direct-current electricity on healing in vitro. Deep flexor tendons of rabbits were excised, transected, repaired, and grown in an acellular culture medium for seven, 14, 21, or 42 days. Tendons through which a continuous 7-microAmp current was passed at the repair site were compared with nonstimulated controls. The incorporation of (14C)proline and its conversion to (14C)hydroxyproline was measured at seven days. The mean (14C)proline and (14C)hydroxyproline activities were 91% and 255% greater, respectively, in the stimulated group. The activity was also higher in the stimulated group, by 42 days. Histologic sections showed that intrinsic tenoblastic repair may be enhanced with electrical stimulation in vitro.

Softball is a popular recreational and competitive sport among both men and women. The injury rate in softball players is as high as that in baseball and basketball players. We conducted a retrospective analysis of 119 hand injuries in 108 patients treated at the University of Chicago hand clinic. All of the injuries were caused by the impact of a 16 inch circumference softball. Of the 119 injuries, 87 (73%) had bone involvement. Operative treatment was required in 26 (22%) injuries, 23 involving fractures and 3 involving soft tissue only. There was one (3.8%) operative complication. Of all injuries, 101 (86%) involved the finger joints, including 46 (39%) injuries to the distal interphalangeal (DIP) joint, 48 (40%) to the proximal interphalangeal (PIP) joint, and 7 (6%) to the metacarpophalangeal (MCP) joint. The most common DIP joint injury was a mallet injury. This fracture, the most common single type of injury in our series, accounted for 27% of all injuries. Of all mallet injuries, 86% were fractures. The most common PIP joint injury was a volar plate fracture, the second most common injury in our series. Variables such as the patient's sex, dominance or nondominance of hands, and early or late season play were not associated with a higher risk of injury. Certain parts of the hand, such as the more ulnar digits and the DIP and PIP joints, were at particularly high risk of injury.

We performed a prospective randomized clinical study to determine whether use of a thigh tourniquet influences the incidence of deep venous thrombosis. The lower limbs of patients who were scheduled for elective surgery on the fore part of the foot were randomized and assigned to one of three treatment categories: Group I, no tourniquet; Group II, exsanguination by an Esmarch bandage before tourniquet application; and Group III, exsanguination by elevation of the extremity prior to application of a tourniquet. The 117 limbs of seventy-one patients included in this study were evaluated preoperatively and twenty-four and seventy-two hours postoperatively with 125I-labeled fibrinogen, and preoperatively and seventy-two hours postoperatively with Doppler ultrasound studies and phleborheography. The findings in all of the Doppler ultrasound studies and all of the phleborheograms were normal. Two of the 125I-fibrinogen studies were positive, but subsequent contrast venography revealed that these were false-positive findings. We therefore concluded that the use of a thigh tourniquet does not increase the risk of deep venous thrombosis in patients who have had an operation on the fore part of the foot.

In this article we reviewed nine consecutive patients operated on for cubital tunnel syndrome. They underwent a modification of the Learmonth procedure in which a medial epicondyle osteotomy was performed. The dissection was completed within intermuscular tissue planes to allow the ulnar nerve to be transposed submuscularly. The medial epicondyle was then replaced and secured using two 4.0 mm AO cancellous screws. This article describes an operative technique, which has not been definitively described previously. Eight of nine patients demonstrated both subjected and objective improvement postoperatively. Eight patients returned to work following surgery. We fell that medial epicondylar osteotomy and screw fixation has minimized operative bleeding, subsequent inflammation, and fibrosis. Immediate range of motion activities have been encouraged, and earlier complete rehabilitation demonstrated.

Experience with a successfully treated transepiphyseal fracture-dislocation of the femoral head in a 4-year-old boy, a review of 6 similar injuries from the literature, and consideration of the anatomy of the immature femoral head and neck, suggest that the treatment of choice for this injury is immediate open reduction and internal fixation with a smooth pin followed by cast protection. Contrary to recommendations in the literature, closed manipulation does not seem justified at any time, since it could eliminate residual blood supply to the femoral head by disruption of the soft tissue hinge between the head and neck. In a child, preservation of the blood supply through intra-articular soft parts is even more imperative than in adults.