Effect of pisiform excision or pisotriquetral arthrodesis as a treatment for pisotriquetral arthritis: a biomechanical study.

PURPOSE: To determine whether flexor carpi ulnaris (FCU) forces and tendon displacements change after pisotriquetral arthrodesis or after pisiform excision. METHODS: Nine cadaver wrists were moved through 4 variations of a dart throw motion, each having an oblique plane of motion, but with different ranges of motion and different antagonistic forces. The FCU tendon force and movement were measured in the intact wrist, following pisotriquetral arthrodesis, and following pisiform excision. Changes in force and tendon movement were compared using a repeated measures analysis of variance. RESULTS: After excision of the pisiform, a significantly greater FCU force was required during the 2 variations of the dart throw motion having a larger range of motion and during the smaller motion having a larger antagonistic force. Pisotriquetral arthrodesis did not cause a significant increase in the peak FCU force. Excision of the pisiform caused the FCU tendon to significantly retract during all wrist motions as compared to the intact wrist or after pisotriquetral arthrodesis. CONCLUSIONS: Greater FCU forces are required to move the wrist when the pisiform with its moment arm function has been removed. This occurs during large oblique plane wrist motions and also in a smaller motion when greater antagonistic forces are applied. Excision of the pisiform also allows the FCU to move proximally, again because its moment arm function has been eliminated. CLINICAL RELEVANCE: Excision of the pisiform requires greater FCU forces during large wrist motions and during motions that include large gripping forces such that excision may be a concern in high-demand patients with pisotriquetral arthritis. Although pisotriquetral arthrodesis does not alter the mechanical advantage of the FCU, its use in high-demand patients with pisotriquetral osteoarthritis cannot yet be recommended until the effects of that arthrodesis on midcarpal kinematics are further clarified.

Morphology of the cubital tunnel: an anatomical and biomechanical study with implications for treatment of ulnar nerve compression.

PURPOSE: The purpose of this study is to provide a thorough understanding of the anatomy of the cubital tunnel and to outline specific anatomical parameters of the cubital tunnel retinaculum (CuTR) that might aid in the management of ulnar nerve problems. The hypotheses of this study are (1) that the nerve elongates with elbow flexion and (2) that the cross-sectional area of the cubital tunnel is inversely proportional to the degree of elbow flexion. METHODS: Eleven fresh-frozen cadaver arms were dissected at the medial elbow. The CuTR was identified, and its thickness was measured. After excising the CuTR, we measured the elongation of the anterior and posterior aspects of the ulnar nerve, as well as the length of the CuTR origin/insertion, at increasing intervals of elbow flexion (15°, 30°, 45°, 90°, 120°, and 135°). Using 3-dimensional digitization technology, the surface of the cubital tunnel was recorded at 4 positions of elbow flexion (15°, 45°, 90°, and 135°) and analyzed to define the tunnel geometry. RESULTS: The CuTR origin-to-insertion length and the ulnar nerve length both increased significantly with increasing flexion angle. Both lengths at 90°, 120°, and 135° of elbow flexion were greater than at 15° or 30°. The cubital tunnel area was significantly less at 135° compared to either 45° or 90° of flexion. There was a linear relationship between the cubital tunnel area of the different arms with the corresponding nerve cross-sectional area when measured at the level of the epicondyle and when the arm was at 90° of elbow flexion. CONCLUSIONS: The CuTR begins to stretch at 60° of flexion and continues to stretch with increasing flexion. Similarly, the ulnar nerve is more taut in flexion. The area within the cubital tunnel decreases beyond 90° of elbow flexion. CLINICAL RELEVANCE: Understanding the dynamic anatomical relationships of the cubital tunnel might help in the safe treatment of cubital tunnel syndrome when using minimally invasive techniques and instrumentation.

Wrist tendon forces during various dynamic wrist motions.

PURPOSE: A common treatment of arthritis of the thumb carpometacarpal joint requires all or a portion of the flexor carpi radialis tendon (FCR) to be used as an interpositional graft. The purpose of this study was to examine the in vitro tendon forces in 6 wrist flexors and extensors to determine whether their force contribution changes during various dynamic wrist motions along with a specific application to the FCR. METHODS: We tested 62 fresh-frozen cadaver wrists in a wrist joint motion simulator. During wrist flexion-extension, radioulnar deviation, dart throwing, and circumduction motions, the peak and average tendon forces were determined for the extensor carpi ulnaris, extensor carpi radialis brevis and longus, abductor pollicis longus, flexor carpi radialis, and flexor carpi ulnaris. RESULTS: During a dart-throwing motion, the mean and peak FCR forces were statistically less than during the other 3 motions. Conversely, the mean and peak flexor carpi ulnaris forces were statistically greater during the dart-throwing motion than during the other 3 motions. CONCLUSIONS: Patients who have undergone a surgical procedure in which all or a portion of the FCR has been harvested may experience a decrease in wrist strength with wrist motion, as the FCR tendon normally applies force during wrist motion. The motion least likely to be affected by such surgery is the dart-throwing motion when the force on the remaining FCR is minimized.

Core decompression of the distal radius for the treatment of Kienböck's disease: a biomechanical study.

PURPOSE: The purpose of this study was to evaluate the biomechanical effect of core decompression of the distal radius for the treatment of Kienböck's disease. METHODS: In 7 fresh cadaver upper extremities, axial loads were applied and the pressure in the radiocarpal joint measured using pressure-sensitive film before and after core decompression of the distal radius. RESULTS: Biomechanically, the stiffness of the distal forearm statistically decreased significantly from 229.4 N/mm to 198.6 N/mm after core decompression. No or minimal changes in the distribution of the force in each radiocarpal fossa and ulnocarpal fossa, the area of contact in each fossa, and the location of the centroid of force were observed. CONCLUSIONS: Core decompression of the distal radius in the setting of Kienböck's disease has been documented good clinical outcomes, yet the biomechanical analysis of this surgical technique does not demonstrate obvious unloading of the lunate.

Technique for Insertion of the Conventus Cage for Distal Radial Fracture Fixation.

INTRODUCTION: Use of the intramedullary Conventus DRS Cage and fragment-specific screw fixation of distal radial fractures minimizes soft-tissue trauma, leading to earlier and improved wrist and finger motion while reducing traditional complications seen with internal fixation of distal radial fractures. STEP 1 REDUCE THE FRACTURE: Reduce the fracture with closed or, if necessary, open methods to achieve anatomic restoration of articular congruity, radial inclination, radial length, volar tilt, and coronal shift. STEP 2 PROVISIONALLY STABILIZE THE FRACTURE: Provisionally stabilize the reduced fracture for insertion of the cage and fragment-specific screws with either longitudinal finger-trap traction or longitudinal Kirschner wires. STEP 3 PREPARE FOR CAGE FIXATION: Prepare the distal part of the radius for cavity preparation and insertion of the Conventus DRS Cage. STEP 4 INSERT THE CONVENTUS DRS CAGE: Insert the previously chosen small or large Conventus DRS Cage. STEP 5 FIX THE FRACTURE FRAGMENTS: Anatomically fix the fracture fragments to the cage and radial shaft. STEP 6 CONFIRM FRACTURE STABILITY: Move the wrist through a full range of motion while assessing fluoroscopically whether the fracture has been stabilized with the cage-and-screw construct. STEP 7 CLOSE THE WOUND: Close the skin incision and cutdown wounds and apply dressings. RESULTS: The Conventus DRS Cage has been used for treatment of distal radial fractures in the U.S. for >3 years.

Case report of long-term results of biaxial and volz total wrist arthroplasty.

The purpose of this case report was to look at the long-term (average 17.8 years) results of total wrist arthroplasty. Of the 12 wrists (9 patients) available for evaluation, 7 wrists still had the arthroplasty in place whereas 5 wrists had been revised to an arthrodesis. The average age at time of arthroplasty for those requiring an arthrodesis was 17 years less than those not requiring an arthrodesis. This suggests that there is a higher incidence of loosening when total wrist arthroplasty is performed in younger patients, perhaps due to these younger patients having higher demands or having more severe rheumatoid arthritis. In this younger population, the implant metacarpal stem cut out in three wrists and ulnar drift occurred in two wrists. All patients said that if given the chance, they would have a total wrist arthroplasty again, despite their long-term results being poor and many of them being revised to a wrist arthrodesis.

A retrospective multicenter study of the Artelon® carpometacarpal joint implant.

BACKGROUND: This study aims to evaluate patient outcomes associated with use of the Artelon® Spacer for the treatment of arthritis of the carpometacarpal joint (CMCJ) of the thumb. METHODS: Patients with Eaton stage I, II, or III carpometacarpal (CMC) joint arthritis and disabling pain that had failed conservative treatment were evaluated at 12, 36, and 48 months postsurgery for changes in pinch, patient satisfaction, pain, range of motion, grip strength, grind test, operative time, and X-ray evidence of subsidence. RESULTS: Complete data was available for 46 subjects and 49 thumbs. A statistically significant improvement in pain when subjected to a first CMC joint grind test, CMCJ stability and patient perception of hand and wrist function following implant insertion was seen. Patient-oriented outcomes showed statistically significant improvement in the Disabilities of the Arm, Shoulder, and Hand; pain; pinch and grip strength; and range of motion. X-ray analysis revealed that none of the distributions of measures of osteophytes, subluxation, and joint space narrowing showed statistically significant change. Bone erosion/remodeling changes of the first metacarpal were statistically significant. CONCLUSIONS: At a follow-up period of 4 years, patients had measured improvement as well as positive self-reported functional improvements following Artelon® implant insertion for the treatment of arthritis of the thumb CMCJ.

Use of a headless compressive screw for distal interphalangeal joint arthrodesis in digits: clinical outcome and review of complications.

PURPOSE: Arthrodesis of the distal interphalangeal joint (DIPJ) or thumb interphalangeal joints can be necessary to treat pain, deformity, or instability associated with arthritis. Compression and rigid fixation are thought to influence fusion rates and time to union favorably. The purpose of the study was to review the clinical outcome and complications associated with the use of a fully threaded headless compression screw for DIPJ arthrodesis. METHODS: Twenty-seven distal interphalangeal or thumb interphalangeal fusions were performed with an axial Mini-Acutrak screw in 22 patients. Charts, surgical reports, and preoperative and postoperative x-rays were reviewed to determine the incidence, time to union, and complications. The minimal follow-up period was 3 months. RESULTS: Twenty-three of the 27 arthrodeses achieved bony union. Complications included symptomatic nonunion (n=1, treated with secondary fusion), asymptomatic nonunion (n=2, left untreated), infection (n=4; 2 patients required implant removal that resulted in nonunion but declined revision) and nail bed injury (n=3). CONCLUSIONS: The Mini-Acutrak screw technique achieves healing rates that are comparable with but not superior to other techniques. Its main advantages are ease of execution, fully buried hardware, and early mobilization; however, the procedure is associated with complications and meticulous technique is required to avoid them. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Unusual complication of an opposition tendon transfer at the wrist: ulnar nerve compression syndrome.

Restoration of thumb opposition by tendon transfer may be necessary in cases of severe thenar atrophy caused by long-standing carpal tunnel syndrome. Routing the extensor indicis proprius transfer subcutaneously around the ulna to reanimate thumb opposition is an accepted procedure and is considered safe. Ulnar nerve compression leading to palsy is possible, however, as shown in the patient presented. Neurolysis failed to improve the palsy. Rerouting of the transfer deep to the ulnar nerve was necessary to treat the iatrogenic condition. Possible nerve compression should be kept in mind when planning a tendon transfer around the ulnar side of the forearm or carpus and when following up with the patient. Early intervention is necessary to prevent permanent sequelae.

Arthroscopic resection of arthrosis of the proximal hamate: a clinical and biomechanical study.

PURPOSE: The purpose of this study was to present a series of patients with arthrosis of the proximal hamate treated by arthroscopic resection. To further investigate this condition a biomechanical study also was undertaken to document the effect this proximal hamate resection has on carpal loading. METHODS: Between 1991 and 2001 there were 23 patients who had arthroscopic proximal hamate resection for the treatment of proximal hamate arthrosis. Twenty-one patients were available for final follow-up evaluation (average, 4.7 y). Patients were evaluated by using a modified wrist score that examined pain relief, patient satisfaction, range of motion, and grip strength. Six cadaver wrists had resection of the proximal hamate. Loads across the carpal and midcarpal joints were documented with pressure-sensitive film before and after proximal hamate resection. RESULTS: Ninety-five percent of the patients had a type II lunate. Twenty-one of 23 wrists had lunotriquetral tears confirmed on arthroscopic examination. Follow-up evaluation revealed 14 excellent, 4 good, 1 fair, and 2 poor results. Biomechanical studies revealed that resection of 2.4 mm of the proximal hamate unloads the hamatolunate articulation without changing the load at the triquetrohamate joint. CONCLUSIONS: Arthrosis of the proximal pole of the hamate seems to be associated closely with tears of the lunotriquetral joint and may be part of the spectrum of ulnar-sided wrist degeneration. Arthroscopic resection of the proximal pole of the hamate appears to be a useful treatment in patients with symptomatic hamate arthrosis, even in those patients with lunotriquetral laxity.