Prediction of ligament length and carpal diastasis during wrist flexion-extension and after simulated scapholunate instability.

PURPOSE: To determine the role of the carpal ligaments during wrist flexion-extension and to understand whether maintaining integrity of only the dorsal scapholunate ligament (SLL) is adequate for maintaining stability of the scapholunate joint. METHODS: This study combined motion analysis and manual digitization of ligament attachment regions to generate predictions of carpal ligament length and implied strain during wrist motion and length changes after simulated ligamentous injury. RESULTS: We modeled 13 ligaments and 22 ligament segments (subportions). We measured ligament length change with respect to wrist angle. A total of 11 segments had minimum stretch or elongation from neutral wrist position over the entire wrist range of motion for any ligament cut condition. The remaining 11 segments had more than 10% stretch in some portion of flexion-extension. In general, ligaments had increased stretch during wrist flexion and after cutting the entire SLL and the dorsal intercarpal ligaments off the scaphoid. CONCLUSIONS: Disruption of the membranous and palmar portions of the SLL and the dorsal intercarpal ligament off the scaphoid did not result in the development of an increased 3-dimensional scapholunate gap, as measured by differences in ligament length calculations between the scaphoid and lunate. This may indicate a predynamic instability condition (before clinical signs and x-ray findings) that is stabilized by the dorsal SLL, preventing the increase in the 3-dimensional scapholunate gap. This may also support surgical treatment recommendations, which suggest that repair of the dorsal component only of the SLL will be effective. Disruption of the dorsal intercarpal ligament off the scaphoid or lunate did not result in further significant changes. Therefore, the dorsal SLL has an important role in preventing scapholunate ligament instability. CLINICAL RELEVANCE: These results provide insight into the abnormal kinematics as various ligaments are compromised.

Clinical applications of perforator-based propeller flaps in upper limb soft tissue reconstruction.

PURPOSE: A propeller flap is an island flap that moves from one orientation to another by rotating around its vascular axis. The vascular axis is stationary, and flap movement is achieved by revolving on this axis. Early propeller flaps relied on a thick, subcutaneous pedicle to maintain vascularity, and this limited the flap rotation to 90°. With increasing awareness of the location and the vascular territory perfused by cutaneous perforators, it is now possible to design propeller flaps based on a single perforator, so-called "perforator-based propeller flaps." These flaps permit flap rotation up to 180°. We present the results of upper limb soft tissue reconstruction using perforator-based propeller flaps. We constructed a treatment strategy based on the location of the soft tissue defect and the perforator anatomy for expedient wound coverage in 1 stage. METHODS: All perforator-based propeller flaps derived from 3 institutions that were used for upper limb soft tissue reconstruction were retrospectively analyzed. The parameters studied included the size and location of the defect, the perforator that was used, the size and shape of the flap, the direction (ie, clockwise or counter-clockwise) of flap rotation, the degree of twisting of the perforator, the management of the donor site (ie, linear closure or skin grafting), and flap survival (recorded as the percentage of the flap area that survived). RESULTS: Twelve perforator-based propeller flaps were used to reconstruct upper limb soft tissue defects in 12 patients. Six different perforators were used as vascular pedicles. The donor defects of 11 flaps could be closed primarily. One flap was partially lost in a patient with electrical burns. CONCLUSIONS: Perforator-based propeller flaps provide a reliable option for covering small- to medium-size upper limb soft tissue defects.

Thumb interphalangeal joint extension by the extensor pollicis brevis: association with a subcompartment and de Quervain's disease.

PURPOSE: First dorsal compartment anatomy was analyzed for the presence of a separate compartment for the extensor pollicis brevis (EPB) tendon and the ability of the EPB to extend the thumb interphalangeal (IP) joint in order to determine if these characteristics were associated with each other, and with de Quervain's disease. METHODS: Two groups were studied: (1) 90 cadaver wrists, 28 to 89 years, 38 male and 52 female specimens; and (2) 143 patient wrists, 21 to 82 years, 18 men and 125 women, in which the first dorsal compartment was released for treatment of de Quervain's disease. RESULTS: The EPB was in a separate compartment in 102 of 143 of the surgical group and 18 of 90 of the cadaver group. The EPB was able to extend the IP joint in 56 of 143 of the surgical group and 19 of 90 of the cadaver group. When the EPB was able to extend the IP joint, it was in a subcompartment in 49 of 56 of the surgical group and 9 of 19 of the cadaver group. When the EPB was able to produce IP extension in the cadaver group, it was inserted on the distal phalanx or the extensor hood. CONCLUSIONS: In a substantial number of people undergoing surgery for de Quervain's disease and in cadavers, the EPB can extend the thumb IP joint. When it does, particularly in patients with de Quervain's disease, it is likely to reside in a subcompartment of the first dorsal compartment. The incidences of a subcompartment for the EPB and the ability of the EPB to extend the thumb IP joint were higher in the de Quervain's patient population than in the cadaver group.

Variations of capitate morphology in the wrist.

PURPOSE: This anatomical study details and categorizes variations in capitate morphology and associated structures in the human cadaveric wrist. METHODS: We dissected 107 cadaveric wrists. Capitate morphology, the presence of capitate and hamate ridges, the lunate types, and the width of the medial hamate facet of type II lunates and 4th carpometacarpal joint types were recorded. RESULTS: Three types of capitate were identified. The flat type (69/107, or 65%) was characterized by a horizontally oriented (radio-ulnar) lunate-capitate articulation and a longitudinally oriented (proximal-distal) scaphoid-capitate articulation. The flat type was associated with type I lunates or type II lunates with a smaller facet. The spherical type (23/107, or 22%) was associated with a concave articulation formed by the scaphoid and lunate articulations, with an indistinct border between the scaphoid and lunate facets. The width of the medial hamate facet of type II lunates in wrists with a spherical-type capitate was

Fibroblast growth factor-2 enhances functional recovery of reinnervated muscle.

Long-term denervation of muscles results in fibrosis and fat replacement, which prevent muscles from regaining contractile function despite reinnervation. Therefore, prevention of muscle atrophy between nerve repair and muscle reinnervation may improve the functional outcome. A variety of growth factors play significant roles in muscle mass modulation and muscle regeneration. The purpose of the present study was to investigate the effect of fibroblast growth factor-2 (FGF2) and nerve growth factor (NGF) on muscle mass modulation after denervation and reinnervation using a nerve-to-muscle neurotization model. Growth factors were injected into the anterior tibial muscle after direct neurotization of muscles every 7 days up to 4 weeks after surgery. FGF2 significantly increased the amplitude of compound muscle action potentials (CMAPs), wet muscle weight, and the number of motor endplates, especially at higher concentration, compared to the vehicle. In contrast, NGF did not increase either the amplitude of CMAPs or muscle weight, although it significantly increased the number of motor endplates. These findings indicate that both growth factors enhance reinnervation of muscles; however, only FGF2 is involved in muscle mass modulation.