Surgical treatment of simple syndactylism with secondary deep digital flexor tendon contracture in a Basset Hound.

A five-month-old, female Basset Hound was presented for lameness associated with a fused 3rd and 4th digital pad on the left hind limb (simple incomplete syndactyly), and secondary contracture of the deep digital flexure tendon of the 3rd and 4th digit. An onychectomy of the third phalanx of the third and fourth digits was performed. Following the operation, the dog gained good use of the affected limb for one month until intermittent non-weight bearing lameness developed. A second surgery was performed six months later, partially removing the second phalanx of digits three and four. Follow-up reports indicate that the dog is doing well and is without lameness. This is the first report of deep digital flexor tendon contracture and surgical treatment of this complication in canine simple syndactylism.

Evaluation of a canine total-elbow arthroplasty system: a preliminary study in normal dogs.

OBJECTIVE: Short-term, in vivo evaluation of a total-elbow arthroplasty (TEA) system in normal dogs. STUDY DESIGN: Prospective evaluation comparing pre- and postoperative findings. ANIMALS: Six normal, skeletally mature, large-breed dogs. METHODS: Physical, radiographic, and force-plate gait examinations were performed on all dogs before surgery. TEA was performed in the dogs using a canine TEA system. Examinations were repeated every 8 weeks for 24 weeks, with an additional examination at 52 weeks. Pre- and postoperative findings were compared. RESULTS: The TEA led to an excellent outcome in 3 of 6 dogs. Force-plate gait examination found that the dogs continued to improve over time and had a peak vertical force (PVF) in the surgical limb that was 99.6% of normal (range, 95.8% to 106.4%) 52 weeks after surgery. Major problems encountered during the postoperative time period were non-weight-bearing lameness (1 dog), osteomyelitis (1 dog), and fracture of the ulna (1 dog). CONCLUSIONS: TEA can be successfully performed in dogs. CLINICAL RELEVANCE: Based on 1-year data, TEA can be successfully performed in dogs and could be considered as a treatment alternative for adult dogs with severe osteoarthritis and lameness of the elbow joint.

Anatomic determinants of first metatarsophalangeal flexion moments in hallux valgus.

A laboratory cadaver model was used to assess the effects of the major anatomic components of hallux valgus deformity on first metatarsophalangeal flexion moments. The individual components of the flexor hallucis longus' effective tendon moment arm were evaluated as a function of imposed hallux valgus, of hallux pronation, and of combined hallux valgus and pronation. To simulate the effects of distal first metatarsal surgery, the components' changes after metatarsal head lateral translation or supination were assessed. Significant changes in effective tendon moment arm occurred with increases in the hallux valgus angle, with changes in the hallux pronation angle, and with combined increases in the hallux valgus angle and hallux pronation angles. The changes involved primarily were a redirection of the moment vector's projection within the superior and inferior plane or medial and lateral plane, rather than an appreciable alteration of the magnitude of the resultant. By contrast, neither translational nor rotational displacements of the metatarsal head influenced any of the individual components of the effective tendon moment arm.

In vivo validation of in vitro testing of hallucal flexor mechanics.

OBJECTIVE: The purpose of this study was to validate an in vitro method of testing first metatarsophalangeal joint mechanics. DESIGN: We compared the orientation of the resultant moment of hallucal plantarflexion in cadaveric specimens undergoing loading of the flexor hallucis longus to the plane of the active great toe plantarflexion moment in normal volunteers. BACKGROUND: Frontal plane deviation of hallucal plantarflexion is a fundamental component of the altered biomechanics in hallux valgus. METHODS: The cadaveric model utilized dynamic loading of the flexor hallucis longus and static loading of the remaining muscles of the great toe. The in vivo method involved measurement of force output with isometric hallucal plantarflexion in the standing position. The medial-lateral and superior-inferior forces as well as the angle of the resultant moment in the clinically relevant frontal plane for both groups were quantified. RESULTS: We found no significant difference between the frontal plane forces of each group. The directional orientations in the frontal plane also displayed a marked similarity, with an average lateral deviation of 0.63 degrees (P = 0.99) for each group. CONCLUSIONS: The lack of a significant difference between the cadaveric and clinical methods of finding the resultant hallucal moment indicates that the cadaveric method accurately simulates in vivo internal flexor muscular loading of the great toe.

The effect of hallux sesamoid excision on the flexor hallucis longus moment arm.

Surgical treatments for chronic, painful hallux sesamoid disorders typically involve partial or complete resection of 1 or both sesamoids. Although these approaches generally result in satisfactory symptom relief, their effect on biomechanical function of the major hallux flexors is not completely understood. The effects of selective sesamoid resections on the effective tendon moment arm of the flexor hallucis longus tendon were evaluated. Twelve fresh frozen cadaver first rays were each mounted in a device that held rigid the metatarsal. A ramp-controlled displacement of an MTS ram supplied a functional load input force to the flexor hallucis longus. The components of the resultant output force necessary to resist the input flexor hallucis longus force were transduced simultaneously by a multicomponent load cell. Subsequently, 3 progressively more extensive seasamoid resections were done: (1) distal hemiresection, (2) complete resection, and (3) resection of both sesamoids. Six specimens were tested with the medial sesamoid removed first and 6 with the lateral sesamoid removed first. Statistical analysis showed that significant decreases in the effective tendon moment arms occurred with full medial sesamoid resection, full lateral sesamoid resection, and resection of both the medial and lateral sesamoids.

The effect of hallux sesamoid resection on the effective moment of the flexor hallucis brevis.

In this cadaver study, the functional significance of the hallux sesamoid bones was quantified by measuring the effective tendon moment arm (ETMA) of the flexor hallucis brevis (FHB) force. (The ETMA differs from the anatomic tendon moment arm in that ETMAs are determined by the experimentally measured moment of the tendon force, rather than by the actual location and orientation of the tendon pull in the joint). The intact case was compared with three levels of progressive sesamoid resection: distal half of the medial sesamoid excised, entire medial sesamoid excised, and both the medial and lateral sesamoids excised. Five dorsiflexion angles of the metatarsophalangeal joint were tested, ranging from -10 degrees to 50 degrees. A known active load was applied to the FHB muscle of fresh frozen cadaver specimens while the corresponding resisting forces from three orthogonally mounted transducers were being recorded. Results showed that the ETMAs decreased significantly (P < .05) only with the excision of both sesamoids. The percent decrease in ETMA was smallest at dorsiflexion angles of -10 degrees and 15 degrees (4.3% and 2.4%, respectively) and largest at dorsiflexion angles of 25 degrees, 35 degrees, and 50 degrees (29.2%, 22.4%, and 26.7%, respectively). The clinical significance of the results is that distal hemiresection of the medial sesamoid or full medial sesamoid excision is unlikely to appreciably compromise the effective mechanical advantage of the FHB muscle. However, this mechanical advantage may be profoundly diminished by excision of both hallux sesamoids.