Volar plating of AO C3 distal radius fractures: biomechanical evaluation of locking screw and locking smooth peg configurations.

PURPOSE: The goal of this study was to determine whether locking screws or smooth locking pegs optimize fixation of AO C3 intra-articular distal radius fractures. A secondary goal was to determine which combinations of locking screws and smooth locking pegs influence construct stability. METHODS: In anatomic radius models, AO C3 intra-articular distal radius fractures were fixed using volar locking plates. For the first part, 16 specimens were randomized to receive either 2 locking screws or 2 smooth locking pegs in each of the 3 pairs of holes in the plate. For the second part, 30 specimens were randomized to receive any 4 combinations of locking screws and smooth locking pegs in each of the 3 pairs of holes. Axial loading to failure was applied. RESULTS: Constructs consisting of 4 smooth locking pegs within the lunate fragment were significantly weaker than constructs with 4 locking screws (means 626 N vs 981 N, respectively). Constructs with smooth locking pegs in the ulnar positions of the lunate fragment were weaker than with locking screws in these positions (means 737 N vs 977 N, respectively). Locking screws in the subchondral position of the lunate fragment were stronger than smooth locking pegs in these positions (means 1,227 N vs 934 N, respectively) and any other combination (means 1,227 N vs 942 N, respectively). CONCLUSIONS: Use of locking screws as opposed to smooth locking pegs for AO C3 intra-articular distal radius fractures, particularly subchondral and in the ulnar side of the lunate fragment, optimizes construct stability. This may have implications on postoperative rehabilitation protocols and may limit costs related to use of volar locking plates.

Indirect reduction and percutaneous fixation versus open reduction and internal fixation for displaced intra-articular fractures of the distal radius: a randomised, controlled trial.

A total of 179 adult patients with displaced intra-articular fractures of the distal radius was randomised to receive indirect percutaneous reduction and external fixation (n = 88) or open reduction and internal fixation (n = 91). Patients were followed up for two years. During the first year the upper limb musculoskeletal function assessment score, the SF-36 bodily pain sub-scale score, the overall Jebsen score, pinch strength and grip strength improved significantly in all patients. There was no statistically significant difference in the radiological restoration of anatomical features or the range of movement between the groups. During the period of two years, patients who underwent indirect reduction and percutaneous fixation had a more rapid return of function and a better functional outcome than those who underwent open reduction and internal fixation, provided that the intra-articular step and gap deformity were minimised.

Endoscopic versus open surgical treatment of carpal tunnel syndrome.

The impact of CTS is significant as evidenced by the fact that only back injuries result in greater rates of employee absenteeism in the workplace. CTR is now the most commonly performed surgical procedure in the United States. Earlier efforts using open surgical techniques were associated with significant morbidity, which some would argue is greater than that associated with the disease itself. The addition of endoscopy to surgeon's armamentarium offers the promise of decreased morbidity associated with the surgical treatment of CTS. Evidence indicates that when compared with open CTR, endoscopic CTR results in earlier achievement of patient satisfaction and functional outcomes. As a result, it is becoming clear that endoscopic surgery is a safe and effective method of treating CTS.

Disorders of the thumb sesamoids.

The subsesamoid joints of the thumb are a common site of arthritis, but their small size makes diagnosis of disorders challenging. The sesamoid and subsesamoid joints may also be injured acutely with the volar plate complex during hyperextension injuries, and may sometimes produce mechanical dysfunction. Simple excision of chronically painful sesamoids provides excellent relief.

Axonal regeneration stimulated by the combination of nerve growth factor and ciliary neurotrophic factor in an end-to-side model.

The aim of this study was to investigate the potential for stimulating axonal regeneration in the context of end-to-side coaptation using a combination of nerve growth factor and ciliary neurotrophic factor in the rat sciatic nerve model. Four experimental groups (n = 8) were used: end-to-side coaptation only, end-to-side coaptation plus growth factor injection, primary repair, and nontransferred gap control. Twenty weeks after surgery histologic analysis showed that the ratio of axon density was significantly increased for the growth factor injection group. Histologic evidence suggested contamination from the proximal peroneal stump. Electrical stimulation and muscle weights showed that the target muscles had been reinnervated in all groups except the nontransferred gap control group. These data support the conclusion that the use of nerve growth factor and ciliary neurotrophic factor in combination may enhance regeneration in the peripheral nervous system. This is consistent with previous reports on the central nervous system and suggests a potential application in future studies aimed at improving peripheral nerve regeneration. Another conclusion is that contamination from the proximal peroneal stump may explain the regeneration observed in the end-to-side model. Further study using retrograde labeling is needed to establish the origin of the regenerating axons. Finally, evidence suggests that regenerating axons can use the epineurium of an intact nerve to bridge a gap in continuity.

Arthroscopic repair of triangular fibrocartilage complex injuries.

The triangular fibrocartilage complex is a functionally and anatomically intricate group of structures located at the ulnar aspect of the wrist. Injury to this structure affects the biomechanics of the wrist and makes functional restoration difficult. This article reviews the anatomy, biomechanics, diagnosis, and arthroscopic treatment of triangular fibrocartilage complex injuries.

Traumatic and reconstructive problems of the scaphoid.

The management of acute scaphoid fractures should be oriented on the concept of fracture stability, ease of reduction, associated ligamentous injury, and risk of impaired blood supply, rather than the direction of the fracture line or location of the fracture within the scaphoid. The lack of predictability of successful fracture union and prognostic discrepancies of historic and contemporary classifications may be related to subtle differences of the internal vascular architecture of each scaphoid. Because the possibility of impaired vascularity is greater with fractures located in the proximal third, stable internal fixation is indicated to provide mechanical stability and fracture surface contact to enhance revascularization. Improved healing rates in a shorter time and earlier rehabilitation with percutaneous techniques of internal fixation have produced a clear shift from classic conservative treatment to internal skeletal fixation. Although the rates of union of well-vascularized nonunions have not been dramatically improved with the use of internal fixation as compared with inlay bone grafting, the restoration of scaphoid anatomy and prevention of malunion and associated carpal collapse with interpositional bone grafting techniques will reduce the risk of osteoarthritis.

Using intact nerve to bridge peripheral nerve defects: an alternative to the use of nerve grafts.

This preliminary study was conducted to determine whether a regenerating peripheral nerve in a rat model can use the epineurium of an intact nerve to bridge a nerve gap defect. To create the intact nerve bridge a 1-cm segment of the peroneal nerve is resected leaving a gap defect. The proximal and distal peroneal nerve stumps are sutured 1-cm apart, in an end-to-side fashion, to the epineurium of the intact tibial nerve. The following experimental groups were used (n = 12): group A, immediate primary repair of resected segment; group B, intact nerve bridge technique; group C, nerve autograft; and group D, gap in situ control. Evaluation 12 weeks after surgery included measurement of the tibialis anterior muscle contraction force, axonal counting, wet weight of the tibialis anterior muscle, and histologic examination. The results of this animal study support 3 main conclusions: regenerating axons can use the epineurium of an intact nerve to bridge a gap in nerve continuity; when using functional recovery to assess regeneration, there is no significant difference between standard nerve autografts and the intact nerve bridge technique; and based on histologic examination, the intact nerve bridge technique does not injure the intact tibial nerve used to bridge the gap defect. Taken together, the results of this preliminary animal study suggest that the intact nerve bridge technique may be a potential alternative to standard nerve autografts in appropriate circumstances. Further investigation in a higher animal model is warranted before considering clinical application of the intact nerve bridge technique.

Displaced scaphoid fractures treated with open reduction and internal fixation with a cannulated screw.

BACKGROUND: This study was performed to determine if the accuracy of screw placement was improved with use of the Herbert-Whipple cannulated screw compared with use of the AO/ASIF cannulated screw and also to evaluate the functional results in patients with an acute displaced fracture of the waist of the scaphoid treated with open reduction and internal fixation with a cannulated screw. METHODS: We retrospectively reviewed the results for thirty-five patients in whom an acute displaced fracture of the waist of the scaphoid had been treated with internal fixation with use of a cannulated screw. The patients were divided into two groups; Group 1 consisted of nineteen patients managed with a 3.5-millimeter cannulated AO/ASIF screw from 1990 through 1997, and Group 2 consisted of sixteen patients managed with a Herbert-Whipple screw from 1993 through 1997. RESULTS: There were no clinical or radiographic differences between the two groups. The average time to union (and standard deviation), confirmed with tomography, was 4.2 +/- 1.2 months for Group 1 and 4.0 +/- 1.2 months for Group 2. Both screws significantly improved the alignment of the scaphoid and decreased carpal collapse (p < 0.01). Importantly, the use of either cannulated screw improved the height-to-length ratio and the lateral intrascaphoid angle, which were correlated with an increase in the range of motion of the wrist (r = 0.584 and 0.625). In addition, both screws allowed for accurate placement in the central portion of the proximal pole. Regardless of the type of screw used, the time to union increased with increasing age of the patient (r = 0.665) and with increasing initial displacement of the fracture (r = 0.541). Within both groups, the time to union was longer for the patients who smoked (p < 0.01). CONCLUSIONS: Within both groups, cannulated screw fixation maintained the corrected fracture alignment and promoted healing and return of function. Our study shows cannulated screws to be a safe and effective method of treatment.

Repair of peripheral nerve defects in the upper extremity.

Repair of peripheral nerve defects in the upper extremity using end-to-end coaptation is accomplished by one of four techniques: in situ mobilization, rerouting and transposition, joint positioning, and bone shortening. A key concern is the amount of tension generated when nerves are elongated to overcome a gap defect. The evidence indicates that elongation should be limited to 8% to 10% of the original length to avoid neural ischemia. It should be noted, however, that when repairs are delayed, the vascularity of nerves is increased. As a result, compared with acute injuries, chronic injuries will tolerate the same degree of elongation with less neural ischemia despite increased stiffness. The mesoneural attachments along each end of the nerve may be safely stripped to a distance of 8 to 12 cm when mobilizing the nerve. Larger nerves tolerate greater lengths of mobilization than smaller nerves. The maximum amount of mobilization that does not produce ischemia can be expressed as a ratio of the diameter of the nerve to the length mobilized and its value is 1:45. The amount of nerve mobilization required for a secondary repair may be reduced by the initial application of tension to unrepaired nerves, thereby reducing the amount of retraction. As the interval to repair increases, nerve retraction results in up to a six-fold increase in the gap defect that must be overcome. Finally recommendations exist for the repair of peripheral nerve segmental defects in the acute setting.

The physiology of nerve transplantation.

As microsurgical techniques improve, attempts to restore function after severe nerve injury place greater demands upon the use of nerve grafts. Viable Schwann cells within these grafts are necessary to maximize nerve regeneration. Progress in decreasing nerve allograft antigenicity and the host response through immunosuppression may provide results comparable to nerve autografts. Although pretreatment methods aimed at reducing allograft antigenicity have yielded inconsistent and overall unsatisfactory results, cryopreservation can maintain Schwann cell viability and shows promise as a means of tissue banking. In addition, tissue typing for MHC I or II antigens and advances in immunosuppressive therapy have rendered encouraging results in experimental models. The use of transplanted nerve allografts remains experimental, yet efforts to understand the host rejection response, advances in immunotherapy, and the development of neurotrophic factors continue to reveal significant benefits over standard treatment methods.

Thumb trapeziometacarpal joint arthritis: partial trapeziectomy with ligament reconstruction and interposition costochondral allograft.

Qualitative and quantitative outcomes were assessed clinically and radiographically in 41 patients (46 thumbs) with thumb basal joint arthritis limited to the trapeziometacarpal joint treated with hemiresection arthroplasty of the trapezium, flexor carpi radialis ligament reconstruction, and allograft costochondral interposition graft. Results of the validated Disability of Arm, Shoulder, and Hand questionnaire at a mean follow-up time of 42 months (range, 24-48 months) revealed that 90% of the patients had a high level of function with minimal symptoms. Important improvements in web space with increased palmar and radial abduction and grip and pinch strength measurements were observed. The trapeziometacarpal space had decreased 21% after surgery while trapeziometacarpal subluxation was 16% compared with 21% before surgery. There was an inverse correlation between the loss of trapezial height and subluxation and clinical outcome. The results of this study demonstrate that although the preoperative trapezial height was not maintained, the reconstructed thumbs remained stable, with little subluxation and improved clinical outcomes. (J Hand Surg 2000; 25A:61-76.

Is end-to-side neurorrhaphy effective? A study of axonal sprouting stimulated from intact nerves.

The purpose of this study was to determine if axonal sprouting across an end-to-side coaptation could be stimulated and if so, to identify the source of the regenerating axons. Mechanical trauma, the method used to stimulate axonal sprouting, was compared to a control group with coaptation only and an additional non-grafted control group. After a 20-week recovery period, electrical stimulation revealed that the target muscles had been reinnervated in all groups except the non-grafted control group. Axonal counting demonstrated a significant increase for the mechanical trauma group compared to the control group with coaptation only [ratio of the density of axons/microm2 of the experimental to the contralateral control side: 2.78+/-0.11 vs. 0.96+/-0.15, respectively, p<0.002). Tibialis anterior muscle weights were significantly increased for both groups vs. the non-grafted control group (ratio of experimental to the contralateral control side: coaptation-only control, 0.539+/-0.024; mechanical trauma, 0.538+/-0.036 vs. nongrafted control, 0.220+/-0.003, p<0.002). Of importance, this study provides evidence that the intact tibial nerve functions as a bridge for regenerating axons derived from the proximal peroneal stump. This suggests an alternative explanation to successful end-to-side axonal sprouting, and questions the clinical utility of end-to-side coaptation.

The effect of thumb metacarpophalangeal ulnar collateral ligament attachment site on joint range of motion: an in vitro study.

Although reconstruction of the torn thumb metacarpophalangeal (MCP) joint ulnar collateral ligament (UCL) has been shown to reduce symptoms, final joint motion may be different from that of the uninjured state. It was hypothesized that nonanatomic repositioning of the UCL might affect joint motion; therefore, the effect of UCL attachment site on MCP range of motion was investigated. The UCL and MCP joint capsule were visualized in each of 8 fresh cadaveric hands without otherwise disrupting the joint. The centers of the ligament attachments were marked with pins and each specimen was mounted on a testing frame capable of applying loads through the flexor and extensor tendons. After measuring the flexion, extension, and radial and ulnar deviation ranges of motion of the intact specimen, the origin of the ligament (on the metacarpal) and an attached bone block were elevated and repositioned 2 mm proximal and 2 mm palmar and range of motion was tested. The origin was reattached in its anatomic location and the insertion of the ligament was similarly elevated and displaced 2 mm in distal, dorsal, and palmar directions. Compared with the intact joint, palmar placement of the UCL origin on the metacarpal increased radial deviation (from a mean of 18 degrees to a mean of 27 degrees); proximal placement of the origin decreased it (from 18 degrees to 10 degrees). Similarly, dorsal placement of the UCL insertion on the phalanx increased radial deviation (from 18 degrees to 25 degrees) and distal positioning of the insertion decreased it (from 18 degrees to 11 degrees). Relative to intact joint flexion range of motion (mean, 57 degrees), distal placement of the UCL phalangeal insertion restricted motion (mean, 47 degrees), as did palmar placement (mean, 48 degrees). Extension and ulnar deviation motions were unaffected by ligament attachment position. This study demonstrates that nonanatomic reconstruction of the UCL alters normal MCP joint range of motion.

Evidence for a polyclonal etiology of palmar fibromatosis.

X chromosome inactivation patterns at the androgen receptor locus were evaluated to determine clonality in microdissected lesional tissue and in leukocytes from 2 women with Dupuytren's disease. The tissue from both patients generated a polyclonal pattern of X chromosome inactivation of the human androgen receptor gene. This finding supports a polyclonal reactive process as the underlying etiology for palmar fibromatosis.

Intra-articular fractures of the distal aspect of the radius.

Intra-articular distal radius fractures are a heterogeneous group of injuries with different fracture patterns. The existing classification systems are helpful for describing the fractures but not for assessing their stability or for deciding which surgical approach to use. Patients who have a fracture with at least 1.0 mm of displacement of the articular surface may benefit from open surgical treatment. Improved diagnostic imaging with CT is helpful for fracture classification and surgical planning. The options for surgical treatment include limited open reduction and internal fixation, arthroscopically assisted internal fixation, and open reduction and internal fixation. The surgical approach is determined on the basis of the initial displacement of the fracture. Patients who have a displaced fracture of the volar rim may benefit from a volar approach; those who have a dorsally displaced fracture, from a dorsal approach; and those who have an impacted fracture such as a die-punch fracture, from a dorsal approach that provides better visualization of the articular surface. The long-term functional outcome is determined in part by the severity of the fracture as defined by the amount of comminution, the initial severity of displacement, and the number of fracture fragments. The accuracy of the reconstruction of the articular surface, with the goal of establishing congruency to within 1.0 mm, is also important in order to minimize the risk of late osteoarthrosis. Of all of the extra-articular parameters, restoration of the length of the radius is the most important for enhancing recovery of motion and grip strength and for preventing problems involving the distal radioulnar joint--the so-called forgotten joint in distal radial fractures.

Intrafocal (Kapandji) pinning of distal radius fractures with and without external fixation.

Seventy-three patients were treated with either intrafocal pinning (Kapandji technique) alone or in combination with external fixation between 1988 and 1993 for extra-articular fractures of the distal radius (with or without a nondisplaced extension into the radiocarpal articular surface) with inadequate alignment after initial closed reduction. Sixty-one patients were available for follow-up examination at an average of 34 months (range, 24-71 months). The average age was 52 years (range, 16-84 years). Thirty-three of the patients were female. The patients all had dorsally displaced extra-articular fractures, although 56% had a nondisplaced extension of the fracture into the radiocarpal joint and 46% had a nondisplaced fracture extending into the distal radioulnar joint. The patients were separated into groups based on age, degree of comminution, and whether external fixation was also used. In the older patients, range of motion, grip strength, and pain relief were significantly better when external fixation was used, even when only 1 cortex of the radius demonstrated comminution. In the younger patients, good results in terms of range of motion, grip strength, and pain relief were obtained when percutaneous intrafocal pins were used alone in patients with comminution of only 1 surface of the radius (<50% of the metaphyseal diameter). When > or = 2 sides of the radial metaphysis were comminuted, the patients with external fixation had better results than those without external fixation. Although the correction of palmar tilt and radial tilt did result in better functional results, the restoration of radial length had the most significant effect on range of motion and grip strength.

Two-, four-, and six-strand zone II flexor tendon repairs: an in situ biomechanical comparison using a cadaver model.

A dynamic in vitro model of zone II flexor tendon repair was used to compare gliding resistance, gap formation, and ultimate strength of the 2-, 4-, and 6-strand repair techniques. Each of 12 hands was mounted to a loading frame with 3 flexor tendons attached to individual pneumatic cylinders. A spring attached to a pin through the distal end of each digit provided a 1.25-kg resistance force. The force required to flex each proximal interphalangeal joint to 90 degrees was determined. Following this, the tendons were sectioned and each was repaired using a different technique so that each specimen acted as its own control. The 2- and 4-strand core sutures were placed using a suture interlock technique with radial and ulnar grasping purchase of the tendon on each side of the transverse part of the repair. Each repair was accomplished using a single core stitch with the knot buried between the tendon ends. The 4-strand repair involved an additional horizontal mattress suture with the knot buried. Repair of the dorsal side of the tendon was performed followed by core suture placement. The palmar portion of the peripheral locking suture was completed after core suture placement. Following repair, each hand was remounted on the frame and cycled 1,000 times. After cyclic loading, the resulting gap between the repaired ends of each tendon was measured, the tendons were removed from the hand, and each was loaded to failure in tension. All tendon repairs showed a small, but not statistically significant, increase in gliding resistance after reconstruction. The 2-strand repair had significantly greater gap formation after cyclic loading (mean gap, 2.75 mm) than either the 4-strand (0.30 mm) or 6-strand (0.31 mm) repair. The tensile strength of the 6-strand repair (mean, 78.7 N) was significantly greater than either the 4-strand (means, 43.0 N) or 2-strand (mean, 33.9 N) repair.

Ulnar shortening combined with arthroscopic repairs in the delayed management of triangular fibrocartilage complex tears.

The functional outcome after surgery was determined in 21 patients an average of 29 months (range, 24-52 months) after surgery to evaluate the efficacy of arthroscopic repair of triangular fibrocartilage complex (TFCC) tears and ulnar shortening. All of the patients had reparable lesions of the TFCC treated after a delay of more than 6 months from the time of injury. The patients' average age was 32 years and all patients had wrist pain limiting them from work and/or sports prior to surgery. After surgery, there was a significant relief of pain (p < .01). Grip strength and range of motion averaged 83% +/- 18% and 81% +/- 16%, respectively, of that of the uninjured side. At follow-up evaluation, 14 patients with repairs underwent follow-up studies; the TFCC was noted to be intact in 12 patients.

The effects of distal radius fracture malalignment on forearm rotation: a cadaveric study.

Seven fresh cadaveric specimens were used to determine the loss of forearm rotation with varying distal radius fracture malalignment patterns. Uniplanar malunion patterns consisting of dorsal tilt, radioulnar translation, or radial shortening were simulated by creating an osteotomy at the distal end of the radius, orienting the distal fragment position using an external fixator, and maintaining the position with wedges and a T-plate. Rotation of the forearm was produced by fixing the elbow in a flexed position and applying a constant torque to the forearm using deadweights. Forearm rotation was measured with a protractor. Dorsal tilt to 30 degrees and radial translation to 10 mm led to no significant restriction in forearm pronation or supination ranges of motion. A 5-mm ulnar translation deformity resulted in a mean 23% loss of pronation range of motion. Radial shortening of 10 mm reduced forearm pronation by 47% and supination by 29%.