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.

Systemic immune response to peripheral nerve transplants across major histocompatibility class-I and class-II barriers.

The use of peripheral nerve transplantation in limb reconstruction has been limited by tissue rejection. In order to identify the major histocompatibility antigens involved in tissue rejection, mutant strains of inbred mice, differing from the parent strain (C57BL/6) by either major histocompatibility complex Class I (B6.C-H2bml mice) or Class II (B6.C-H2bml2 mice), were used in models of nerve transplantation. One, 2, and 3 weeks after nerve or skin transplantation, the immune response in the recipient animal was monitored with use of lymphocyte-dependent cytotoxicity and complement-dependent cytotoxicity assays. Skin transplants were used for comparison as the gold standard of a nonvascularized graft with an easily observable success or failure. There was no significant cellular immune response by the lymphocyte-mediated cytotoxicity assay when nerve or skin transplants involved an isolated Class-I or Class-II mismatch, but there was a significant response 2 weeks after transplantations across a combined Class-I and Class-II barrier for nerve (p < 0.04) or skin (p < 0.03). An antibody response to the grafts occurred for both skin and nerve transplants but only when a combined barrier was involved. This preliminary study, using a mouse model, suggests that nerve transplantation-may be performed without systemic evidence of rejection with only a partial cross match of the major histocompatibility complexes, thus decreasing the complexity of tissue typing necessary for tissue banking.

Non-union of the scaphoid. Treatment with cannulated screws compared with treatment with Herbert screws.

We retrospectively reviewed the results for thirty-four patients in whom a non-union of the scaphoid had been treated with bone-grafting and internal fixation with use of one of two types of screws as well as the temporary placement of Kirschner wires parallel to the screw to prevent rotation. The patients were divided into two groups: Group 1 contained sixteen patients who had been managed with a Herbert screw from 1986 through 1989 and Group 2, eighteen patients who had been managed with a 3.5-millimeter cannulated AO/ASIF screw from 1990 through 1992. There were no clinical or radiographic differences between the two groups. The time to union, confirmed with tomography, was 7.6 +/- 3.6 months for Group 1 and 3.6 +/- 1.2 months for Group 2. This difference was significant (p < 0.01). Both screws significantly improved the alignment of the scaphoid and decreased carpal collapse (p < 0.05). Regardless of the type of screw used, the time to union was significantly shorter when the screw had been placed in the central one-third of the scaphoid (p < 0.05). Seventeen of the eighteen cannulated screws had been placed centrally, compared with seven of the sixteen Herbert screws (p < 0.01).

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.

Incidence of hepatitis C in patients requiring orthopaedic surgery.

We tested prospectively for hepatitis C virus (HCV) in one orthopaedic surgeon's operative practice for one year. Of 425 consecutive patients, 19 (4.5%) were positive for HCV infection using a second-generation screening assay. The highest correlation with a positive test was the presence of tattoos and the second highest was intravenous drug abuse, but only after a second interview, since most patients did not report this risk on the initial questionnaire. Based on the criteria of the US Public Health Services algorithm, nine (47%) of the patients with a positive initial screening test or 2.2% of the 425 patients, had hepatitis C (both anti-HCV-positive and elevated alanine aminotransferase). In this group of nine, the presence of tattoos had the highest and intravenous drug abuse the second highest correlation, also after the second interview. There is no vaccine available for the prevention of HCV infection, and prophylactic immunoglobulin therapy has no proven value for primary exposure.

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.

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.

Allogeneic bone in the treatment of tumors, trauma, and congenital anomalies of the hand.

Because autogenous bone grafts are histocompatible by definition and because the hand does not require massive bone grafts, one may question the indications for using allogeneic bone in the hand. Although humans have been shown to develop donorgraft specific antibodies following large osteochondral allografts, these antibodies have not yet been noted after smaller bone grafts nor is the clinical significance of these antibodies clear. The use of allogeneic bone better satisfies the architectural and strength requirements for reconstruction when there is a need for osteochondral grafts, strong cortical grafts to allow secure fixation and early motion, and small tubular grafts that meet the demands of minimizing bulk in the hand. For the repair of osteochondral defects, autogenous grafts (ie, fibular head or metatarsal head) impose donor site deficits that can be clinically significant. In addition, grafts such as the fibular head do not provide reconstruction of a congruent joint surface. Strong cortical bone is an asset in metacarpal reconstruction; it enhances the quality of internal fixation, which in turn allows hand therapy to be started early, an essential treatment following hand injuries. A stiff hand after reconstruction will result despite excellent bony reconstruction if the fixation does not allow early motion. Autogenous cortical grafts donor sites (eg, ulna or tibia) can cause donor site morbidity, including fracture of weakened bone. The need for small tubular grafts is especially important in pediatric patients. Strong autogenous corticocancellous grafts are difficult to obtain in children, and these grafts are bulky and difficult to insert. In addition, for adults and children, the lack of a donor site means a much shorter hospital stay.

Sural nerve grafting for lower extremity nerve injuries.

Fourteen consecutive patients who had sural nerve grafts to reconstruct the sciatic or peroneal nerve were retrospectively evaluated to determine the functional return of reinnervation. A standardized functional evaluation to assess motor and sensory return of the injured compared with the contralateral side was employed as a means of normalizing the data. The dorsiflexion and plantar flexion strength were quantitatively measured to determine the recovery of muscle strength, and recorded as a percentage of the strength of the contralateral extremity as well as by assigning a motor grade. Sensory recovery was evaluated by sensory grade, two-point discrimination, and response to Semmes-Weinstein monofilaments. The average age of these 14 patients was 20 years (range 8-63 years). All but one of the patients regained protective sensation and five patients regained useful motor function. Four of the five patients regaining useful function were pediatric patients. Improved functional outcome was correlated to the nerve injured, patient age, mechanism of injury, length of graft, and the delay to grafting. The return of lower extremity function, obviating the need for bracing, can occur in children but is a rare occurrence in the adult patient although protective sensation is routinely gained and disabling paresthesias from neuromas are avoided.

Use of radial forearm flaps to treat complications of closed pilon fractures.

Between 1986 and 1990, five patients have been treated for full-thickness skin loss proximal to the level of the anterior joint line of the ankle following open reduction and internal fixation of closed C3 (ASIF) pilon fractures. The average delay from injury to the initial open reduction and internal fixation was 4.6 days. Anteromedial and posterolateral incisions were used to expose the fractures, resulting in a bipedicle flap over the anterior aspect of the ankle joint at the time of the initial surgery. The minimum distance between these two incisions for these five patients was 6.0 to 9.0 cm (average of 7.4 cm). Free tissue transfers using the radial forearm flap were effective in providing durable but thin coverage for this difficult problem of soft-tissue coverage in an area requiring a thin flap with a long vascular pedicle. The risk for skin necrosis at the time of surgery may be minimized by spacing the incisions up to 12.0 cm apart in addition to avoiding the period of maximal tissue ischemia occurring 3 to 6 days after the injury.

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.

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.

Biomechanical comparison of methods used to treat Kienböck's disease.

The surgical approach to Kienböck's disease is largely dependent on the stage of the disease and the ulnar variance pattern. Many of the surgical treatments are designed to unload the lunate, halt disease progression, and allow for possible revascularization. This article reviews a collection of studies investigating the biomechanical effects of load-altering procedures. Knowledge of the biomechanical impact of the various operative interventions is clinically useful in creating a treatment algorithm.

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.

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.

Avascular necrosis after scaphoid fracture: a correlation of magnetic resonance imaging and histology.

In this study 12 male patients with fractures of the middle third of the scaphoid had an magnetic resonance imaging study before open reduction and internal fixation in conjunction with bone grafting of the scaphoid. The patients' average age was 27 years (range, 17 to 37 years). At the time of surgery biopsy specimens were obtained from both the proximal and distal poles of the scaphoid. The length of time before surgery ranged from a minimum of 1 1/2 months in recently displaced fractures to a maximum of 10 years in established nonunions. Results of the biopsy showed that six patients had avascular necrosis noted in the proximal pole fragment. In three of these six patients avascular necrosis was confirmed by the absence of tetracycline labeling despite positive uptake noted in biopsy specimens from the bone graft site; the other three patients did not receive tetracycline labeling. Magnetic resonance imaging showed that all six of the patients with biopsy specimens of the proximal poles showing avascular necrosis demonstrated decreased signal intensity in the proximal pole fragment, whereas the plain radiographs demonstrated changes in the proximal pole in only three of the six patients. A decreased signal intensity from the proximal pole of the scaphoid may indicate a poor prognosis inasmuch as only three of the six patients had healing of the fracture even with bone grafting and internal fixation.

Peripheral nerve transplantation: the effects of predegenerated grafts and immunosuppression.

Research involving nerve transplantation has shown that tissue rejection limits the neurologic recovery unless the host is immunosuppressed. This study investigates an alternative to permanent or temporary immunosuppression using a rat model with nerve transplants from Brown-Norway rat donors to bridge defects in the sciatic nerve of Lewis rat recipients as these two inbred strains differ at both major and minor histocompatibility loci. The specific aim of this study was to evaluate if predegenerated nerve grafts decreased the tissue rejection and improved the neurologic recovery of animals with allogenic nerve grafts to avoid the problems associated with either short- or long-term immunosuppression. The animals in the experimental groups received cyclosporin-A, predegenerated grafts, both, or neither. The predegenerated grafts were produced by division of the nerve three weeks prior to grafting to allow for Wallerian degeneration to occur. The outcome was assessed by measurements stressing functional recovery (sensory testing, gait analysis, joint flexion contracture), studies of muscle recovery (muscle weight and hydroxyproline concentration), and histologic studies (axonal counts and inflammatory reaction). The animals receiving the predegenerated grafts without cyclosporin did have an improved recovery (joint flexion contracture 35 degrees +/- 8 degrees and hydroxyproline ratio 1.52 +/- 0.16) as compared to the joint flexion contractures and hydroxyproline ratios of the allograft group of animals without either cyclosporin-A or pretreatment and the ungrafted control group (47 degrees +/- 18 degrees, 1.68 +/- 0.34, and 53 degrees +/- 15 degrees, 4.50 +/- 0.27, respectively, p less than 0.01). However, all the isograft groups and allograft groups with cyclosporin-A, regardless of whether the graft had been predegenerated or not, had greater neurologic recovery than the allograft group with predegenerated grafts but without cyclosporin-A by the same parameters (p less than 0.01). Allograft groups with short-term immunosuppression with cyclosporin-A did as well as isograft groups, and isograft groups with predegenerated grafts did not do any better than isografts without pretreatment (p less than 0.01).

Posttraumatic sesamoid arthritis of the metacarpophalangeal joint of the thumb.

The articular interface between the radial sesamoid and the radial condyle of the metacarpal head, which is the radial subsesamoid joint, is the most frequently involved area of abnormality in the metacarpophalangeal joint complex. More than 85% of all adult cadavers demonstrate degenerative arthritis of the radial subsesamoid joint. Confusing this condition with degenerative arthritis of the metacarpophalangeal joint may lead to unnecessary joint fusions. The predisposition of the radial subsesamoid to degenerative arthritis is related to the asymmetry of the palmar condyles of the metacarpal. The ulnar sesamoid has a flatter and broader condyle compared with the radial sesamoid, which rides on a high, narrow ridge. Thirty-six patients with symptomatic sesamoiditis have been treated by sesamoidectomy since 1978. Twenty-one of these patients were available for follow-up examination between 1 and 5 years after surgery, and 19 had relief of proximal thumb pain after sesamoidectomy.