Treatment of Angular Limb Deformities in Foals

Single-incision drilling technique to achieve hemiepiphysiodesis of the distal metacarpus - complications and outcome in 207 foals with metacarpophalangeal varus deformities

OBJECTIVE

To report the outcome of foals treated for metacarpophalangeal varus deformity with a single-incision drilling technique for hemiepiphysiodesis of the distal lateral metacarpal physis.

STUDY DESIGN

Retrospective case-control cohort study.

ANIMALS

Thoroughbred foals (n = 207), 171 age- and sex-matched maternal siblings.

METHODS

Medical records (2017-2020) were reviewed for signalment, limb(s) treated, location of the surgery, and any reported complications. Follow-up radiographs obtained for the yearling sale were assessed for abnormalities. Horses were matched to maternal siblings using an online database. Sales and racing performance data were compared between cohorts.

RESULTS

The average age at the time of surgery was 97 days. The treated limb was the left front in 52, right front in 31, both fronts in 119, unknown in 5. Three horses developed calcinosis circumscripta lesions adjacent to the physis, which were removed successfully. No radiographic abnormalities associated with the surgery site were detected on yearling prepurchase radiographs. There were no differences in sales and racing performance data between treated horses and maternal controls.

CONCLUSION

Hemiepiphysiodesis is a safe and effective treatment for metacarpophalangeal varus deformities in foals. No negative effect on sales or racing performance was identified.

CLINICAL SIGNIFICANCE

This technique avoids risks, costs, and the need for second surgery associated with an orthopedic implant. The surgeon should be aware of the potential for development of a calcinosis circumscripta lesion with this technique.

Surgical management of a severe congenital deformity of the hind limb in a Shetland pony foal – a case report

This case report describes the surgical management of a severe congenital deformity in a Shetland pony. A two-week-old foal was presented with the right hind limb showing a 90-degree torsion of the tarsal region towards the medial side and the metatarsophalangeal joint forced in a 90-degree extension behind the right tarsus. As assessed through radiography, the tibial malleoli and the trochlea of the talus were poorly developed, the flexor tendons inserted topographically correctly on the phalanges but due to articular torsion, the tenaculum of long and lateral digital extensor tendons were projected laterally and the common digital extensor tendon on the medioplantar aspect. At the age of one month, a corrective ostectomy of the tibial malleoli, trochlear ridge, and talus was performed to reposition the adjacent bones. The tarsal bones were repositioned through an arthrotomy and subsequently the tarsal region fused by means of two cortex screws inserted in a lag fashion. Complete correction of the torsion was achieved through metatarsal osteotomy. A 20-hole 3.5-mm reconstruction plate was used for stabilization of the tibia and metatarsus, resulting in a pantarsal arthrodesis. Partial tibia shortening was performed to improve angulation of the tarsal region. At nine months after surgery, the pony was keeping the right limb hoof sole on the ground.

Application of computed tomography and stereolithography to correct a complex angular and torsional limb deformity in a donkey

OBJECTIVE

To report the evaluation, surgical planning, and outcome for correction of a complex limb deformity in the tibia of a donkey using computed tomographic (CT) imaging and a 3D bone model.

STUDY DESIGN

Case report.

ANIMALS

A 1.5-year-old, 110 kg donkey colt with an angular and torsional deformity of the right pelvic limb.

METHODS

Findings on physical examimation included a severe, complex deformity of the right pelvic limb that substantially impeded ambulation. Both hind limbs were imaged via CT, and imaging software was used to characterize the bone deformity. A custom stereolithographic bone model was printed for preoperative planning and rehersal of the surgery. A closing wedge ostectomy with de-rotation of the tibia was stabilized with 2 precontoured 3.5-mm locking compression plates. Clinical follow-up was available for 3.5 years postoperatively.

RESULTS

CT allowed characterization of the angular and torsional bone deformity of the right tibia. A custom bone model facilitated surgical planning and rehearsal of the procedure. Tibial corrective ostectomy was performed without complication. Postoperative management included physical rehabilitation to help restore muscular function and pelvic limb mechanics. Short-term and long-term follow-up confirmed bone healing and excellent clinical function.

CONCLUSION

CT imaging and stereolithography facilitated the evaluation and surgical planning of a complex limb deformity. This combination of techniques may improve the accuracy of the surgeons' evaluation of complex bone deformities in large animals, shorten operating times, and improve outcomes.

Corrective Osteotomy of a Metacarpal Deviation Caused by Fracture in a 9-Month-Old German Fleckvieh Heifer

OBJECTIVE

To describe the surgical treatment of a metacarpal deviation caused by an untreated Salter-Harris type I fracture in a heifer.

STUDY DESIGN

Case report.

ANIMAL

9-month-old German Fleckvieh heifer.

METHODS

A closing wedge osteotomy was performed to correct deviation of fused metacarpal III and IV. A triangular bone wedge was removed and the proximal and distal fragments of the bone were brought into apposition and stabilized with an 11-hole T-plate. A full-limb cast was applied postoperative.

RESULTS

Radiographs were taken at 2, 4, and 6 weeks postoperative. No postoperative complications occurred and the heifer was discharged from the clinic 51 days after surgery. Radiographs taken 6 months after discharge showed periosteal callus formation around the closing wedge osteotomy. At 24 months postoperative, implants were intact and the heifer was in good general condition.

CONCLUSION

Closing wedge osteotomy was successfully performed in a heifer with a metacarpal deviation, correcting the malunion after a untreated Salter-Harris type I fracture. Radiographs showed evidence of osteotomy healing and the heifer had full use of the affected leg at 24 months postoperative.

Musculoskeletal Pathology

The current understanding of pathology as it relates to common diseases of the equine musculoskeletal system is reviewed. Conditions are organized under the fundamental categories of developmental, exercise-induced, infectious, and miscellaneous pathology. The overview of developmental pathology incorporates the new classification system of juvenile osteochondral conditions. Discussion of exercise-induced pathology emphasizes increased understanding of the contribution of cumulative microdamage caused by repetitive cyclic loading. Miscellaneous musculoskeletal pathology focuses on laminitis, which current knowledge indicates should be regarded as a clinical syndrome with a variety of possible distinct mechanisms of structural failure that are outlined in this overview.

Complications after two transphyseal bridging techniques for treatment of angular limb deformities of the distal radius in 568 Thoroughbred yearlings

REASONS FOR PERFORMING STUDY

Surgical correction of carpal angular limb deformities by growth retardation is commonly undertaken with a screws and tension band wire loop technique (S&W) or a single transphyseal screw (STS). This study compares complications after S&W and STS bridging in the distal radius of Thoroughbred yearlings.

OBJECTIVE

To compare the prevalence of complications serious enough to require follow-up radiographs following either S&W or STS surgery for growth manipulation in the distal radius of Thoroughbred yearlings.

METHODS

Medical records and radiographs from Thoroughbred yearlings (age range 261-457 days) treated for carpal angular limb deformities at a single hospital over 2 years were reviewed. Each of the techniques was used exclusively during a single year. The complication threshold criterion for inclusion was the need for nonroutine radiographs of the operated site anytime after implant insertion or removal.

RESULTS

Of 568 horses, 253 received S&W and 315 received STS. Horses were of similar age at the time of surgery for STS and S&W. Single transphyseal screws were left in place for a significantly shorter amount of time (16 days). Sex, the limb(s) treated and medial vs. lateral placement were not significantly different between techniques. Complications included physitis post implant removal, metaphyseal collapse post implant removal, infection, overcorrection and seroma formation severe enough to require radiography. Physitis and metaphyseal collapse occurred significantly more frequently with STS compared with S&W. Infection, overcorrection and seromas were not significantly different between techniques.

CONCLUSION

The STS and S&W techniques are both viable treatment options for correction of carpal angular limb deformities. However, horses treated with the STS technique have a significantly increased risk of developing physitis or metaphyseal collapse.

POTENTIAL RELEVANCE

Horses treated with STS bridging have a significantly increased risk of developing the post correction complications of moderate to severe physitis and metaphyseal collapse compared with horses treated with S&W bridging.