Daniel J. Burba

Effects of Extracorporeal Shock Wave Therapy on Desmitis of the Accessory Ligament of the Deep Digital Flexor Tendon in the Horse

OBJECTIVE To evaluate the effects of extracorporeal shock wave therapy (ESWT) on collagenase-induced lesions in the accessory ligament of the deep digital flexor tendon (ALDDFT) of horses. STUDY DESIGN Paired, blinded controlled study. ANIMALS Eight Thoroughbred horses (3 mares, 5 geldings; mean ± SD weight, 464 ± 26 kg, mean age, 8 ± 1.7 years). METHODS Lesions were created in both ALDDFTs of all horses by injection of 2 × 10(3) IU of collagenase type I. Percent lesion and structure (fiber alignment and echogenicity) were quantified with ultrasonographic imaging 3, 6, and 9 weeks after collagenase injection. After ultrasound examinations, ESWT (1000 shocks at 0.15 mJ/mm2) was applied to 1 ALDDFT in each horse. ALDDFT were harvested 15 weeks after collagenase injection and the microstructure, mRNA levels of collagen types I and III, and collagen and glycosaminoglycan content were evaluated. RESULTS There were no differences in percent lesion, echogenicity, or fiber alignment between control- and ESWT-treated ligaments at each evaluation time; however, compared with 3-week values, there was a significant increase in percent lesion and echogenicity for EWST treated ligaments at 6 weeks and significant decrease in both variables for treated and control ligaments at 12 weeks. Fiber alignment improved significantly at 9 weeks in controls and at 12 weeks in treated and control ligaments. Collagen type I mRNA levels were significantly higher in the ESWT treatment group compared with the control group 15 weeks after collagenase injection though differences in other mRNA levels, microstructure, and composition were not significant. CONCLUSIONS Our results do not support an effect of ESWT on collagenase-induced lesions in the equine ALDDFT.

Musculoskeletal Injury in Thoroughbred Racehorses : Correlation of Findings Using Multiple Imaging Modalities

Adaptive and nonadaptive stress remodeling in Thoroughbred racehorses leads to most of their musculoskeletal injuries, and imaging plays an important role in its detection. Bone scintigraphy is important for detecting stress remodeling and stress fractures and aids in decision making when more than one lesion is present on MRI or radiographic examinations. MRI likely represents the best modality for the assessment of osteoarthritis of the metacarpophalangeal and metatarsophalangeal joints. Ultrasonography remains important as the first modality for the assessment of tendon and ligamentous injury. However, injury to the proximal suspensory and distal sesamoidean ligaments may be best diagnosed with MRI.

Long Term Outcome After Laser Assisted Modified Forssell's in Cribbing Horses

Objective To (1) report long-term outcome after laser assisted modified Forssells procedure; (2) describe the prevalence of postoperative complications; and (3) identify risk factors associated with outcome. Study design Retrospective case series. Animals Horses (n = 119). Methods Medical records (1994–2012) of horses that had laser assisted modified Forssells procedure were reviewed. Signalment, preoperative duration of cribbing, postoperative complications and outcome were recorded. Results Follow-up was available for 90 horses; 76 had stopped cribbing for >1 year. Of 14 horses that resumed cribbing, median relapse time was 6 months. Preoperative cribbing duration was significantly associated with an increased probability of unsuccessful outcome when horses cribbed for >3 years before surgery (odds ratio of positive outcome: OR = 0.14, 95% CI: 0.02, 0.95). Overall, 22.2% horses had postoperative complications (hematoma, seroma, infection, and prolonged drainage). Conclusions Laser assisted modified Forssells is a very effective (84.4%) surgical treatment of cribbing behavior in horses. Preoperative cribbing duration was identified as a significant risk factor associated with unsuccessful surgical outcome.OBJECTIVE To (1) report long-term outcome after laser assisted modified Forssells procedure; (2) describe the prevalence of postoperative complications; and (3) identify risk factors associated with outcome. STUDY DESIGN Retrospective case series. ANIMALS Horses (n = 119). METHODS Medical records (1994-2012) of horses that had laser assisted modified Forssells procedure were reviewed. Signalment, preoperative duration of cribbing, postoperative complications and outcome were recorded. RESULTS Follow-up was available for 90 horses; 76 had stopped cribbing for >1 year. Of 14 horses that resumed cribbing, median relapse time was 6 months. Preoperative cribbing duration was significantly associated with an increased probability of unsuccessful outcome when horses cribbed for >3 years before surgery (odds ratio of positive outcome: OR = 0.14, 95% CI: 0.02, 0.95). Overall, 22.2% horses had postoperative complications (hematoma, seroma, infection, and prolonged drainage). CONCLUSIONS Laser assisted modified Forssells is a very effective (84.4%) surgical treatment of cribbing behavior in horses. Preoperative cribbing duration was identified as a significant risk factor associated with unsuccessful surgical outcome.

Compressive Forces Achieved in Simulated Equine Third Metacarpal Bone Lateral Condylar Fractures of Varying Fragment Thickness with Acutrak Plus Screw and 4.5 mm AO Cortical Screws

OBJECTIVES To compare compression pressure (CP) of 6.5 mm Acutrak Plus (AP) and 4.5 mm AO cortical screws (AO) when inserted in simulated lateral condylar fractures of equine 3rd metacarpal (MC3) bones. STUDY DESIGN Paired in vitro biomechanical testing. SAMPLE POPULATION Cadaveric equine MC3 bones (n=12 pair). METHODS Complete lateral condylar osteotomies were created parallel to the midsagittal ridge at 20, 12, and 8 mm axial to the epicondylar fossa on different specimens grouped accordingly. Interfragmentary compression was measured using a pressure sensor placed in the fracture plane before screw placement for fracture fixation. CP was acquired and mean values of CP for each fixation method were compared between the 6.5 mm (AP) and 4.5 mm (AO) for each group using a paired t-test within each fracture fragment thickness group with statistical significance set at P<.05. RESULTS AO screw configurations generated significantly greater compressive pressure compared with AP configurations. The ratio of mean CP for AP screws to AO screws at 20, 12, and 8 mm, were 21.6%, 26.2%, and 34.2%, respectively. CONCLUSION Mean CP for AP screw fixations are weaker than those for AO screw fixations, most notably with the 20 mm fragments. The 12 and 8 mm groups have comparatively better compression characteristics than the 20 mm group; however, they are still significantly weaker than AO fixations. CLINICAL RELEVANCE Given that the primary goals of surgical repair are to achieve rigid fixation, primary bone healing, and good articular alignment, based on these results, it is recommended that caution should be used when choosing the AP screw for repair of lateral condylar fractures, especially complete fractures. Because interfragmentary compression plays a factor in the overall stability of a repair, it is recommended for use only in patients with thin lateral condyle fracture fragments, as the compression tends to decrease with an increase in thickness.