Sorrel J Langley-Hobbs

Comparison of Kinematic Variables in Defining Lameness Caused by Naturally Occurring Rupture of the Cranial Cruciate Ligament in Dogs

OBJECTIVE To (1) discover kinematic variables that differ between dogs with cranial cruciate ligament rupture (CCLR) and control dogs and (2) to identify suitable outcome variables for longitudinal studies on the effects of surgical interventions for CCLR in dogs. STUDY DESIGN In vivo case-control comparison. ANIMALS Dogs with unilateral CCLR (n=16), and no other detectable neurologic or orthopedic disease and 10 dogs without CCLR, neurologic, or orthopedic disease. METHODS Kinematic data was collected from dogs as they walked at constant speed on a treadmill, using an infrared camera system and adhesive reflective markers applied to the pelvic limbs. Data on 5 selected variables was extracted and comparisons made between paired pelvic limbs in both CCLR and control dogs and between control and CCLR dogs. RESULTS Comparisons in CCLR dogs revealed significant differences between affected and unaffected limbs for many examined variables; the largest differences were in paw velocity and stifle angular velocity. There were highly significant differences between CCLR and control dogs when examining paired limb ratios for 4 of the variables, the largest differences were in stride length and paw velocity. CONCLUSIONS Kinematic analysis provides straightforward and objective methods for defining the lameness associated with CCLR in dogs. Paw velocity and stride length were most notably reliable and not susceptible to systematic alterations in stifle joint dynamics that might be associated with specific surgical procedures. CLINICAL RELEVANCE This study identifies several variables that can provide the objective measurements essential to evaluate the efficacy of surgical interventions for CCLR in dogs.

Survey of 52 fractures of the patella in 34 cats

Stress fractures of the patella were diagnosed in 34 cats with a mean age of two years and five months. Eighteen of the cats had bilateral fractures with a median interval of three months between fractures. All the fractures were transverse and occurred in the proximal aspect or base of the patella with no evidence of trauma. In 43 of the patellae there was radiographic evidence of sclerosis. Repairs with a pin and tension band in 18 cats resulted in a further fracture or failure of fixation in 86 per cent of the cases that were followed up. Ten of the cats had suffered fractures of other bones at different times to the patellae fractures. In the majority of the cats the fracture formed a functional non-union but some cats remained stiff and lame.

Feline Ilial Fractures: Assessment of Screw Loosening and Pelvic Canal Narrowing After Lateral Plating

OBJECTIVE To report the incidence of (1) screw loosening and (2) severity of pelvic canal narrowing in cats after repair of ilial fractures by a lateral bone plate. STUDY DESIGN Case series. ANIMALS Cats (n=21) with ilial fractures. METHODS Medical records (June 1994 to February 2004) and radiographs were reviewed. Retrieved data were: signalment, fracture description, screw purchase, screw loosening, complications, and clinical outcome. Sacral index (SI) was used to objectively assess degree of pelvic canal narrowing. Long-term follow-up was by owner telephone interview or postal questionnaire. RESULTS Screw loosening occurred in 13 cats (62%), with a mean loss of total screw purchase of 13% (range, 0-46%). Pelvic canal narrowing (mean decrease, 25%; range, 5-60%) occurred in all cats. Six cats (28%) had severe pelvic canal narrowing (mean, 52%); 5 of these had signs of recurrent constipation within 12 months postoperatively. Mean loss of total screw purchase in cats with severe pelvic narrowing was 28% compared with 9% for all other cats with narrowing. CONCLUSIONS Lateral plating of ilial fractures in cats is associated with a high incidence of screw loosening. CLINICAL RELEVANCE Pelvic canal narrowing >45% is associated with a high risk of recurrent constipation.

Sacroiliac luxation in the cat: defining a safe corridor in the dorsoventral plane for screw insertion in lag fashion.

OBJECTIVE To define a safe corridor in the dorsoventral plane within the feline sacral body for placement of screws inserted in lag fashion for repair of sacroiliac luxation. STUDY DESIGN Anatomic study. SAMPLE POPULATION Frozen cadaveric feline sacra. METHODS Feline sacra (n=20) were used to perform a radiographic study to define a safe corridor to a depth of 66% of the sacral body width. Two drill start points (A and B) were evaluated. Dorsal exit from the safe corridor was considered unacceptable. RESULTS Forty safe corridors were measured. The mean articular surface was 100+/-6.4 degrees from horizontal. Mean maximum, optimum, and minimum safe corridor drill angles from drill point A were 107+/-6.8 degrees , 97+/-6.9 degrees , and 87+/-7.2 degrees , respectively, from the articular surface. Mean maximum, optimum, and minimum angles from drill point B were 109+/-7.2 degrees , 99+/-7.1 degrees , and 89.5+/-7.2 degrees , respectively. Point B increased the risk of ventral exit from the sacral body. CONCLUSIONS Point A and a drill angle of 90+/-4 degrees for drilling of the feline sacral body is recommended. This margin for error risks ventral exit from the body in 23/40 (58%) of the sacra in this study. Reduction of the margin for error to +/-2 degrees would reduce the risk of ventral exit to 14/40 (35%) of the sacra in this study. CLINICAL RELEVANCE Drilling at 90 degrees to the feline sacral articular surface is recommended. Findings from this study present a strong case for use of angled drill guides.

Feline ilial fractures: a prospective study of dorsal plating and comparison with lateral plating.

OBJECTIVE To (1) report a technique for repair of feline ilial fractures using a dorsally applied bone plate and (2) compare outcome with cats treated by a lateral plate. STUDY DESIGN Prospective study. ANIMALS Cats (n=10) with iliac fractures. METHODS Cats with ilial fractures (January 2005-December 2006) were treated by application of a dorsally applied bone plate. Immediate postoperative radiographs were compared with those taken 4-6 weeks later to assess screw loosening, screw purchase, and pelvic canal narrowing. Owners were contacted for medium-term (>3 month) follow-up. Data were compared with a report of outcome after lateral plating (LP) in 21 cats. RESULTS Mean (+/- SD) screw purchase (89 +/- 11 mm) was significantly greater (P<.01) with a dorsal plate compared with a lateral plate (33 +/- 8 mm). Significantly more screws (P<.01) were used with a dorsal plate (median, 7) compared with a lateral plate (median, 6). Significantly less postoperative pelvic canal narrowing developed in the dorsal plating group between postoperative and 4-6-week follow-up radiography compared with the LP group (2% versus 15%, P<.01). CONCLUSION Dorsal plating of feline ilial fractures results in significantly less screw loosening and pelvic canal narrowing at 4-6 weeks after surgery compared with LP. CLINICAL RELEVANCE Dorsal plating of feline iliac fractures may reduce complications associated with pelvic canal narrowing such as constipation and megacolon.

Patellar luxation as a complication of surgical intervention for the management of cranial cruciate ligament rupture in dogs. A retrospective study of 32 cases.

This retrospective study identified 32 cases of patellar luxation which occurred as a complication of surgical intervention for cranial cruciate ligament rupture (CCLR). The complication was recorded mostly in larger (>/=20 kg) dogs with the Labrador Retriever being the most common breed. The complication followed extra-capsular, intra-capsular and tibial plateau levelling surgery. The mean time from CCLR surgery to the diagnosis of patellar luxation was 14 weeks. The incidence of patellar luxation occurring as a complication of surgical intervention for CCLR was 0.18% of all CCLR corrective procedures. Corrective surgery for patellar luxation was successful in 79% of stifles. The patellar reluxation rate was significantly lower (p = 0.0007) when at least one corrective osteotomy (tibial tuberosity transposition, femoral trochlear sulcoplasty or tibial plateau levelling osteotomy with tibial axial re-alignment) was performed (35%), compared to when corrective osteotomy was not performed (100% patellar reluxation rate). When performing corrective surgery for patellar luxation following CCLR surgery, at least one corrective osteotomy should be performed in order to reduce the patellar reluxation rate. The correction of patellar luxation following surgery for CCLR is challenging and carries a significant rate of failure.

A biomechanical comparison of six different double loop configurations for use in the lateral fabella suture technique

Six different double loop configurations which could be applied to the lateral fabella suture (LFS) technique were subjected to in vitro mechanical testing. Three double loop, single strand and three double loop, double strand configurations were tested. The strongest configuration, with a significantly higher mean ultimate load and load at yield, was the interlocking loop configuration. This is a novel configuration which has not previously been reported. The three double loop, single strand configurations all had higher mean ultimate loads than the double loop, double strand configurations. The double strand group with uneven loop length performed very poorly, with significantly lower mean stiffness and ultimate load than all of the single strand groups. This group also developed unacceptably high levels of elongation during high level cyclic loading.

Vitamin D-dependent rickets type 2 with characteristic radiographic changes in a 4-month-old kitten.

This report describes the presenting signs, biochemical abnormalities, and radiographic changes in a 4-month-old kitten with vitamin D-dependent rickets type 2. Details of therapy are described and possible reasons for treatment failure are discussed.

Treatment of caudal mandibular fracture and temporomandibular joint fracture-luxation using a bi-gnathic encircling and retaining device

Fractures of the caudal portion of the mandible and temporomandibular joint (TMJ) fracture-luxation can be challenging to treat with direct fixation methods. This paper describes a simple technique for the indirect treatment of caudal mandibular fracture and TMJ fracture-luxation using a subcutaneous loop of nylon leader line tunnelled around the maxilla, incisive and nasal bones, and under the mandible, placed just caudal to the canine teeth, and crimped ventral to the mandibular skin: a bignathic encircling and retaining device (BEARD). A BEARD was used to treat two immature dogs with simple, unilateral caudal mandibular fractures, six cats with unilateral injury (two with TMJ luxation, three with TMJ fracture-luxation, one with caudal mandibular fracture), and two cats with bilateral injury (comminuted caudal mandibular fracture with contralateral TMJ luxation; bilateral condylar neck fracture). The BEARD treatment failed short-term due to poor tolerance in one cat, and concurrent injuries and poor initial reduction in another cat. One cat was lost to long-term follow-up. Rostral dental occlusion was normal in six out of seven cases, and reported jaw function was normal in seven out of seven cases. The case with poor occlusion had imperfect initial reduction. Complications included dorsal nasal skin swelling or discharge, oesophagostomy tube dislodgement or blockage, BEARD loosening, and regurgitation. Treatment of uni- or bilateral caudal mandibular trauma using a BEARD can lead to clinical union, and normal rostral occlusion, provided that case selection is appropriate and immediate-post-surgical occlusion has been corrected.

Stabilization of Sacroiliac Luxation in 40 Cats Using Screws Inserted in Lag Fashion

OBJECTIVE To (1) identify prognostic indicators for stability after stabilization of sacroiliac luxation with screws inserted in lag fashion and (2) report dorsoventral dimensions of the sacrum in cats. STUDY DESIGN Multicenter retrospective study. SAMPLE POPULATION Cats (n=40) with sacroiliac luxation. METHODS Case records and radiographs of cats presented at the Queens Veterinary School Hospital Cambridge and the Royal Veterinary College Hatfield for screw fixation of sacroiliac luxation were reviewed. Dorsoventral dimensions of 15 feline cadaveric sacral bodies were measured to identify the appropriate implant size for use in fixation with screws inserted in lag fashion. RESULTS Of 40 cats, 13 had left, 14 right, and 13 bilateral sacroiliac luxations. Of 48 screws analyzed, 42 (87.5%) were placed within the sacral body or exited ventrally and 6 (12.5%) were considered malpositioned. Screw purchase within the sacrum was statistically different between unstable and stable repairs (P=.001). Using confidence intervals for screw length within the sacrum and effect on stability, the lowest screw depth that contained 95% of the screws that did not loosen was approximately 60% of the sacral width. Mean dorsoventral sacral dimension at its narrowest point was 5.9+/-1.14 mm. There was no significant difference in the incidence of implant loosening between those luxations that were 100% reduced and those that were <100% reduced (P=.7837). CONCLUSIONS Screw purchase within the feline sacrum of at least 60% of the sacral width significantly reduces the risk of loosening. CLINICAL RELEVANCE Screw placement to a depth of 60% of the width of the feline sacrum is recommended.