William P. Cooney

Flexor tendon forces: In vivo measurements

S-shaped force transducers were developed for measurement of the forces along intact tendons. After calibration, the transducers were applied to the flexor pollicis longus and flexor digitorum superficialis and profundus tendons of the index finger in five patients operated on for treatment of carpal tunnel syndrome. The tendon forces generated during passive and active motion of the wrist and fingers were recorded. For pinch function, the amount of the applied load was measured with a special pinch meter. Tendon forces in the range of 0.1 to 0.6 kgf were measured during passive mobilization of the wrist. Tendon forces up to 0.9 kgf were present during passive mobilization of the fingers. Tendon forces up to 3.5 kgf were present during active unresisted finger motion. Tendon forces up to 12.0 kgf were recorded during tip pinch, with a mean applied pinch force of 3.5 kgf. These results have potential application in determining the amount of force that a tendon repair would have to resist during passive as well as active postsurgical mobilizations.

Difficult wrist fractures. Perilunate fracture-dislocations of the wrist.

Perilunate dislocations of the wrist have a common pathway of disruption that occurs from extensive dorsiflexion injuries. Open reduction and internal fixation of these injuries is required to provide accurate alignment and the option for ligament repair. Both dorsal and palmar surgical incisions may be indicated. Associated injuries to the median nerve must be recognized. Treatment includes scaphoid and radial styloid stabilization with multiple K-wires or internal compression screw (Herbert or Association for the Study of Internal Fixation [ASIF] screws). In these injuries, the lunate must be reduced first and stabilized. The scaphoid proximal segment follows the lunate unless the scapholunate (SL) ligament is torn. The distal scaphoid fragment, capitate, and triquetrum are reduced and aligned with the lunate and need to be held with K-wires. Ligament repair and augmentation may be necessary at both scapholunate and lunotriquetal areas if there has been serious ligament injury. Palmar ligament repair is often required, and we recommend a palmar exploration in most patients along with release of the median nerve. Surgical treatment results of perilunate fracture-dislocations of the wrist appear better than conservative treatment methods, but complications following both indicate the need for improved internal fixation and fracture-dislocation realignment. These fractures are a real challenge to the treating surgeon who must use patience, precise surgical techniques, and careful roentgenographic study (including tomograms and traction views) to assure the best result.

External pin fixation for unstable Colles' fractures.

During a five-year period, a double-pin Roger Anderson apparatus, with pins perpendicularly placed in the second and third metacarpals and in the distal part of the radius, was applied in 130 patients with an unstable Colles fracture. Sixty of the 130 were followed for two years. Shortening was limited to a median of two millimeters and dorsal angulation, to a median of 3 degrees. Wrist dorsiflexion averaged 58 degrees, and volar flexion averaged 50 degrees. Pronation and supination had an average loss of 5 degrees when compared with the uninjured side. Repeat reduction was required in only three patients. Patient assessment revealed that 85 per cent of the patients had good results; 12 per cent, fair; and 3 per cent, unsatisfactory. Objective analysis (McBride system) revealed that 90 per cent had good to excellent results; 8 per cent, fair; and 2 per cent, poor. Ninety-two per cent had no pain, 89 per cent had no deformity, and the mean grip strength was twenty kilograms. Sixteen patients had complications; seven of the sixteen had pin loosening, which occurred most frequently late during the course of treatment and without adverse sequelae.

Perilunate dislocations and fracture-dislocations : a multicenter study

A series of 166 perilunate dislocations and fracture-dislocations from 7 centers was retrospectively studied. The diagnosis was missed initially in 41 cases (25%). A classification system was presented. The perilunate fracture-dislocations were more frequent than the perilunate dislocations at a ratio of two to one. The displacement was dorsal in 161 cases (97%) and palmar in only 5 (3%). The dorsal transscaphoid perilunate fracture-dislocations represented 96% of the dorsal perilunate fracture-dislocations and 61% of the whole series. The clinical and radiologic outcome of 115 perilunate dislocations and fracture-dislocations with at least 1 year and an average of 6 years 3 months of follow-up was studied. Open injury and delay of treatment had an adverse effect on clinical results, whereas anatomical type had less influence. In cases treated early, the clinical results were satisfactory but the incidence of post-traumatic arthritis was high (56%). In the dorsal perilunate dislocation group of pure ligamentous injuries and in the dorsal transscaphoid group, the best radiologic results were observed after open reduction and internal fixation. In the latter group, the fixation of the scaphoid alone was not always sufficient and left occasionally scapholunate dissociation, lunotriquetral dissociation, ulnar translation of the carpus, or other carpal collapse patterns. The initial appraisal of both the osseous and ligamentous pathology was very important.

Functional ranges of motion of the wrist joint.

We have examined 40 normal subjects (20 men and 20 women) to determine the ideal range of motion required to perform activities of daily living. The amount of wrist flexion and extension, as well as radial and ulnar deviation, was measured simultaneously by means of a biaxial wrist electrogoniometer. The entire battery of evaluated tasks could be achieved with 60 degrees of extension, 54 degrees of flexion, 40 degrees of ulnar deviation, and 17 degrees of radial deviation, which reflects the maximum wrist motion required for daily activities. The majority of the hand placement and range of motion tasks that were studied in this project could be accomplished with 70 percent of the maximal range of wrist motion. This converts to 40 degrees each of wrist flexion and extension, and 40 degrees of combined radial-ulnar deviation. This study provides normal standards for the functional range of motion of the wrist.

Surgical treatment of scapholunate advanced collapse

This study reports the outcomes of six different reconstructive procedures for stage II and stage III scapholunate advanced collapse (SLAC) wrist in 55 cases followed an average of 50 months. Scaphoid excision and intercarpal arthrodesis was performed in 31 cases: four-corner arthrodesis in 23 cases and capitolunate arthrodesis in 8 cases. Proximal row carpectomy was performed in 12 cases, radioscapholunate arthrodesis in 5 cases, radioscaphoid arthrodesis in 3 cases, and primary total wrist arthrodesis in 4 cases. Following surgical treatment the majority of patients in all groups had less wrist pain. The nonunion rate was four cases for the capitolunate arthrodesis group compared with two for the four-corner arthrodesis group. Six of 51 motion-sparing cases were converted to total arthrodeses. Scaphoid excision and four-corner arthrodesis reliably diminished wrist pain in patients with stage III SLAC wrist while maintaining a 54 degrees flexion-extension arc. Stage II SLAC wrist can be successfully treated with this procedure, radioscaphoid arthrodesis, or proximal row carpectomy. Of the three procedures, proximal row carpectomy best preserves wrist mobility, with a flexion-extension arc of 71 degrees.

Fractures of the scaphoid: a rational approach to management.

Fractures of the scaphoid can be classified into either undisplaced, stable fractures or displaced, unstable fractures by their roentgenographic appearance. When there is greater than 1 mm of fracture offset or an instability collapse pattern (dorsal lunate rotation) on the lateral view, an unstable, displaced fracture is present. When doubt exists after reviewing routine films, special X-rays, such as radial-ulnar deviation stress views, traction oblique views, or trispiral tomography should be obtained. In acute scaphoid fractures, where no displacement of the fracture fragments or lunate dorsal tilting can be seen, a short-arm thumb spica cast provides satisfactory support for fracture union. A wrist position of volar flexion-radial deviation is preferred to the more traditional positions of wrist extension with radial deviation or wrist extension with ulnar deviation with 100% union rate and no malunions. In displaced scaphoid fractures, a long-arm cast is recommended, with reduction of the fracture by wrist flexion and radial deviation. If accurate reduction is not obtained or is lost during the course of treatment, open reduction and internal fixation should be strongly considered. In scaphoid nonunions, undisplaced fractures can be treated satisfactorily by an inlay bone graft, using either a dorsal or a volar approach. For displaced scaphoid nonunions, either a dorsal approach with internal fixation should be done (particularly if there is evidence of radioscaphoid arthrosis), or a volar approach with internal fixation can be performed. Peg graft techniques had a higher rate of nonunion and secondary arthritis. Nonunions should be immobilized a minimum of 4 months or until roentgenographic union is present.

Normative model of human hand for biomechanical analysis

Abstract A three-dimensional normative model of the hand was established, based on the averaged anatomical structure of ten normal hand specimens. The joint and tendon orientations were defined from biplanar X-ray films. The configurations of the hand at the joints were described by the classic Eulerian angles. Force potential and moment potential parameters were utilized to describe the contribution of each tendon in the force analysis. The mean values of these two parameters were used to compute the designated two points for each tendon at each joint in the normative model. With appropriate coordinate transformations at the joints, the tendon locations and excursions under various functional configurations can be computed. This model can be used to perform force and motion analyses for both normal and pathological hands.

The distal radioulnar ligaments: A biomechanical study

The mechanical roles of the triangular fibrocartilage have been examined in three experiments. Kinematic analysis by a stereophotogrammetric method revealed that the palmar radioulnar ligament was taut in supination and that the dorsal radioulnar ligament was taut in pronation. In full pronation, the palmar radioulnar ligament decreased to an average of 71% of its length in tension. In full supination, the dorsal radioulnar ligament decreased to an average of 90% of its length. Mechanical testing of the triangular fibrocartilage under axial load disclosed a significant laxity (mean: 10.4 mm), which was decreased in pronation. Transverse loading tests demonstrated that the triangular fibrocartilage is less stiff in neutral forearm rotation. Study of the material properties of the palmar and dorsal parts of the triangular fibrocartilage showed these structures to be strong ligaments with material properties similar to those of the radiocarpal ligaments.

Vascularized bone transfer.

We evaluated the results of reconstruction of a skeletal defect with use of a vascularized bone graft from the iliac crest or fibula in 160 patients who had been managed consecutively between 1979 and 1989. The indications for the procedure were a skeletal defect including non-union, resulting from resection of a tumor; traumatic bone loss; osteomyelitis; or a congenital anomaly. The average duration of follow-up was forty-two months (range, twelve to 112 months). For the entire series, the rate of union after the primary procedure was 61 per cent and the over-all rate at the latest follow-up examination (including the patients who had a secondary procedure) was 81 per cent. In a subgroup of seventy-six patients who had union after the primary procedure and did not have additional treatment, the average interval until union was six months and the average interval until full activity was sixteen months. The results were more favorable for the patients who had had reconstruction for resection of a tumor (of sixty-nine patients, fifty-six had union), for a congenital anomaly (of six patients, five had union), or for a non-union without infection (of twenty-five patients, twenty-three had union). The results were less satisfactory for patients who had had the reconstruction for bone loss due to osteomyelitis (of sixty patients, forty-six had union). Our data suggest that vascularized bone transfer for the reconstruction of large skeletal defects is a valuable procedure in appropriately selected patients.