The Effect of Extensor Tendon Adhesions on Finger Motion.

PURPOSE: To quantify the amount and pattern of finger range of motion loss at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints with a simulated extensor tendon adhesion at the level of the proximal phalanx or metacarpal. METHODS: In 10 cadaveric specimens, traction sutures were placed in the forearm extensor digitorum communis and flexor digitorum profundus tendons of the middle and ring fingers. Active motion was simulated by suspending weights from the traction sutures via pulleys. The angles of the MCP, PIP, and DIP joints were measured at the position of maximum flexion and extension. Extensor tendon adhesions were simulated alternately at the proximal phalanx and metacarpal levels of the middle and ring fingers, using suture anchors. Repeat measurements were taken using the same amount of force. RESULTS: There was an average total loss of flexion of 38° and of extension of 6° with a proximal phalanx adhesion, with a greater contribution of flexion loss at the PIP joint. The loss of flexion was 17° and of extension was 50° with a metacarpal adhesion, with a loss of extension mostly at the MCP joint. CONCLUSIONS: The results of this study identified clear patterns of motion loss that are associated with isolated simulated adhesions in different locations along the extensor mechanism. The greatest motion loss occurred at the joint immediately distal to the simulated adhesion. CLINICAL RELEVANCE: Although extrapolation of these findings to clinical relevance remains unclear, the ability to predict the level of adhesion by the pattern of motion restriction may allow for a targeted tenolysis procedure. This would reduce the amount of soft tissue dissection required, which in turn, could be expected to reduce the degree of repeat adhesion formation.

The effect of lunate morphology on the 3-dimensional kinematics of the carpus.

PURPOSE: To assess carpal kinematics in various ranges of motion in 3 dimensions with respect to lunate morphology. METHODS: Eight cadaveric wrists (4 type I lunates, 4 type II lunates) were mounted into a customized platform that allowed controlled motion with 6 degrees of freedom. The wrists were moved through flexion-extension (15°-15°) and radioulnar deviation (RUD; 20°-20°). The relative motion of the radius, carpus, and third metacarpal were recorded using optical motion capture methods. RESULTS: Clear patterns of carpal motion were identified. Significantly greater motion occurred at the radiocarpal joint during flexion-extension of type I wrist than a type II wrist. The relative contributions of the midcarpal and radiocarpal articulations to movement of the wrist differed between the radial, the central, and the ulnar columns. During wrist flexion and extension, these contributions were determined by the lunate morphology, whereas during RUD, they were determined by the direction of wrist motion. The midcarpal articulations were relatively restricted during flexion and extension of a type II wrist. However, during RUD, the midcarpal joint of the central column became the dominant articulation. CONCLUSIONS: This study describes the effect of lunate morphology on 3-dimensional carpal kinematics during wrist flexion and extension. Despite the limited size of the motion arcs tested, the results represent an advance on the current understanding of this topic. CLINICAL RELEVANCE: Differences in carpal kinematics may explain the effect of lunate morphology on pathological changes within the carpus. Differences in carpal kinematics due to lunate morphology may have implications for the management of certain wrist conditions.

Effect of glenoid cementation on total shoulder arthroplasty for degenerative arthritis of the shoulder: a review of the New Zealand National Joint Registry.

BACKGROUND: Despite the lack of literature showing improved results compared with cemented designs, uncemented glenoid components are still commonly used in total shoulder arthroplasty (TSA). Most studies comparing cemented with uncemented glenoids involve small numbers or include patients with inflammatory arthritis. METHODS: New Zealand National Joint Registry data was used to compare the outcomes of uncemented and cemented glenoids in TSA performed for degenerative arthritis. Measured variables were the revision rate and the Oxford Shoulder Score (OSS). RESULTS: Data were retrieved on 1596 patients, with a mean follow-up 3.5 years (range 2-10.7 years), 1065 of whom had a cemented glenoid. There were no significant differences in any preoperative factors between the 2 groups. The revision rate for uncemented glenoids was 4.4 times higher than for cemented glenoids (1.92 vs. 0.44 revisions per 100 component-years, P < .001). Age <55 years was an independent risk factor for revision (P < .001). The most common reason for revision was rotator cuff wear (35.5%) in the uncemented glenoids and loosening (36.3%) in the cemented glenoids. The difference in the mean OSS between the 2 groups was less than 1 point at 6 months (P = .109) and at 5 years (P = .377). CONCLUSION: Uncemented glenoids had a markedly higher revision rate. Patients aged <55 years have the highest revision rate regardless of glenoid fixation method. The higher revision rate in the uncemented glenoid group persisted when the effect of young age was corrected for. There was no clinically or statistically significant difference in the OSS results for clinical outcome between the two groups. LEVEL OF EVIDENCE: Level III, retrospective cohort, treatment study.

Association between screw prominence and vascular complications after clavicle fixation.

CONTEXT: Fixation of clavicle fractures has become more common to prevent symptomatic malunion and nonunion. The subclavian and axillary vessels are in close proximity to the medial two-thirds of the clavicle, placing them at risk from prominent metalware. Injury to these major vessels has the potential to be life or limb-threatening. Despite this anatomical risk, iatrogenic vascular injury associated with clavicle fixation is rare. AIMS: The aim of this study was to identify risk factors associated with modern fixation techniques in reported cases of vascular injury after clavicle fixation. MATERIALS AND METHODS: A literature search was performed, and all identified cases of iatrogenic vascular injury associated with prominent clavicle fixation were analyzed. Clinical details, the total length of the prominent screws and the distance that they protruded from the far cortex were recorded. RESULTS: Five cases were identified; there were four pseudoaneurysms and one arteriovenous fistula. The total length of the offending screw was identifiable in two cases, measuring 26 and 30 mm. The length of screw prominence was identifiable in 3 cases (8, 10 and 10 mm). The pseudoaneurysms presented at 2-10 years following clavicle fixation. Three of these cases developed limb-threatening ischemia. CONCLUSIONS: Vascular complications associated with clavicle fixation are uncommon but potentially limb-threatening. Several associated factors are identified. The authors provide a number of detailed recommendations aimed at preventing these complications.