Comparison of Short‐ and Long‐term Function and Radiographic Osteoarthrosis in Dogs After Postoperative Physical Rehabilitation and Tibial Plateau Leveling Osteotomy or Lateral Fabellar Suture Stabilization

Objectives— To compare short‐ and long‐term functional and radiographic outcome of cranial cruciate ligament (CrCL) injury in dogs treated with postoperative physical rehabilitation and either tibial plateau leveling osteotomy (TPLO) or lateral fabellar suture stabilization (LFS). Study Design— Prospective observational clinical study. Animals— Medium to large breed dogs with naturally occurring CrCL injury (n=65). Methods— Dogs with CrCL injury were treated with either TPLO or LFS and with identical physical rehabilitation regimes postoperatively. Limb peak vertical force (PVF) was measured preoperatively and at 3, 5, and 7 weeks, and 6 months and 24 months postoperatively. Stifles were radiographically assessed for osteoarthrosis (OA) preoperatively and 24 months postoperatively. Results— Thirty‐five dogs had LFS and 30 dogs had TPLO. Radiographic OA scores were significantly increased at 24 months compared with preoperative scores in all dogs. Radiographic OA scores preoperatively and at 24 months were not significantly different between treatment groups. PVF was significantly increased from preoperative to 24 months among both treatment groups but not significantly different between treatment groups preoperatively or at 3, 5, 7 weeks, 6, or 24 months. Conclusion— No significant difference in outcome as determined by ground reaction forces or radiographic OA scores were found between dogs with CrCL injury treated with LFS or TPLO. Clinical Relevance— LFS and TPLO remain good options for stabilizing stifles with CrCL injury with all dogs showing significant functional improvement. This study does not support the superiority of either surgical technique.     

Combination tibial plateau leveling osteotomy and transverse corrective osteotomy of the proximal tibia for the treatment of complex tibial deformities in 12 dogs

Objective: To describe a surgical technique, and outcome, for treatment of proximal tibial deformity (varus, valgus, excessive tibial plateau angle [eTPA], tibial torsion and patellar luxation) by combined tibial plateau leveling osteotomy (TPLO) and transverse corrective osteotomy. Study Design: Cases series. Animals: Dogs (n=12; 19 stifle joints). Methods: Medical records of dogs that had combination TPLO and transverse corrective osteotomy, were reviewed. Pre‐ and postoperative tibial angulation, tibial torsion, tibial plateau angle (TPA), corrective osteotomy technique, method of fixation, and complications were recorded. In hospital re‐evaluation of limb function and alignment and length of time to radiographic healing were reviewed. Long‐term outcome was assessed by visual analog scale (VAS) questionnaire and owner telephone interview. Results: Proximal tibial varus or valgus was present in 68.4%; 73.7% had eTPA; and 47.4% had both. Medial patellar luxation (MPL) was present in 57.9%, of which 47.4% had tibial tuberosity displacement. Severe tibial torsion was present in 68.4%. Mean pre‐ and postoperative TPA was 37.5° and 5.7°, respectively. The mean postoperative mechanical medial proximal tibial angle (mMPTA) and mechanical medial distal tibial angle (mMDTA) were 92.2° (range, 88–96°) and 96.1° (range, 94–101°), respectively. Postoperative surgical complications were documented in 21.0%, which included implant loosening or breakage (5.3%), seroma (5.3%), septic arthritis (5.3%), and infection of the proximal tibia (5.3%). All complications were considered major because they required additional surgery. Mean time to document radiographic healing was 10.4 weeks. In‐hospital re‐evaluation of lameness was obtained at the same time; 82.4% were not lame or had a mild lameness, 17.6% had severe lameness (2/3 with infection). The VAS evaluation revealed excellent results and owner satisfaction in all ten dogs in which long‐term follow‐up was obtained. Conclusions: Long‐term clinical outcome of combination TPLO and transverse corrective osteotomy was excellent, and had a high owner satisfaction. Healing times were comparable to standard TPLO with a similar complication rate.     

Evaluation of Intra‐ and Interobserver Variability and Repeatability of Tibial Plateau Angle Measurements with Digital Radiography Using a Novel Digital Radiographic Program

Objective— To compare the intra‐ and interobserver variability occurring when observers with differing experience levels measure tibial plateau angles (TPAs) with a novel digital radiographic projection program (tibial plateau leveling osteotomy [TPLO] planning program), the Kodak Picture Archiving and Communications System (PACS), and standard sized printed films (SF). Study Design— Cross‐sectional study. Sample Population— Dogs (n=36) with cranial cruciate ligament (CCL) rupture that had a TPLO. Methods— Six observers, divided into 3 equal groups based on experience level, measured TPA on 36 digitally captured radiographic images of tibiae of dogs clinically affected with CCL rupture. Each observer used 3 methods of measuring TPA and repeated the measurements 3 times with each method. The intra‐ and interobserver variability was compared using the coefficient of variation. Results— Averaged over all replications and images, there was no significant difference (P>.05) in the average variability occurring with each method for all but 1 observer. There was no effect of experience level on measurement variability; however, interobserver variability was significantly less with measurements made with the PACS and TPLO planning program compared with measurements made from SF (P<.05). Conclusions— Repeated measurements of TPA made using digital images and computer‐based measurement programs were significantly less variable between observers than those made from images printed on standard radiographic films. Clinical Relevance— Digital radiography and computer‐based measurement programs are effective for determining the TPA, allowing less variability in measurements compared with SF. The ability to manipulate the image may allow better identification of anatomic landmarks.     

Risk factors for tibial tuberosity fracture after tibial plateau leveling osteotomy in dogs

Objective— To evaluate factors that predispose to tibial tuberosity (TT) fracture after tibial plateau leveling osteotomy (TPLO) in dogs.
Study Design— Retrospective study.
Animals— Dogs (n=182) with cranial cruciate ligament (CCL) rupture undergoing 213 TPLO surgeries.
Methods— Medical records and radiographs of 2 groups of dogs that had TPLO surgery (2000–2001, 2004–2005) were evaluated to determine the effect of operative technique and surgeon experience on TT fracture.
Results— TT fracture was diagnosed in 8 dogs (9 TPLO, 4.2% of surgical procedures). Four fractures occurred after unilateral TPLO in 167 dogs (2.4%), 4 fractures occurred after simultaneous bilateral TPLO in 5 dogs (40%), and 1 fracture occurred after staged bilateral TPLO in 36 dogs (2.8%). Simultaneous bilateral TPLO resulted in a 12.4 times higher odds of TT fracture versus unilateral TPLO ( P =.046). The mean absolute thickness of the TT after TPLO was less in dogs sustaining TT fractures (7.2 ± 2.2 mm) than those that did not (10.8 ± 2.7 mm, P <.0001). The odds of fracture decreased by 37% when the absolute TT width postosteotomy increased by 1 mm ( P <.0001). An increase in tibial plateau angle at follow-up versus immediately postoperative was associated with TT fracture ( P =.025). Surgeon experience was not associated with TT fracture.
Conclusion— A combination of surgical decision-making and surgical technique play a role in the occurrence of TT fracture after TPLO. Simultaneous bilateral TPLO was associated with a high percentage of TT fracture.
Clinical Relevance— Careful planning of osteotomy positioning is advised while performing TPLO surgery.     

Risk factors for fibular fracture after TPLO

Objective: To determine (1) risk factors for fibular fracture after tibial plateau leveling osteotomy (TPLO) and (2) if a single postoperative radiographic measurement or measurement ratio of the proximal tibial fragment can be used as a predictor for fibular fracture. Study Design: Multivariate retrospective clinical study. Animals: Dogs (n=326) with cranial cruciate ligament rupture that had TPLO (n=355). Methods: Medical records (January 2004–November 2007) and radiographs of dogs that had TPLO were reviewed. TPLO plate type, distance between tibial plateau and proximal screw, proximodistal tibial plateau fragment length, tibial plateau width, the presence of a fibular drill hole filled with a screw or not, and fibular fractures were recorded. Results: The odds of having a fibular fracture were 10 times greater in dogs with a fibular drill hole than in dogs without a drill hole. The odds of having a fibular fracture were 1.46 times greater for every 4.5 kg increase in body weight. Tibial plateau angle (TPA) at the time of reevaluation was larger than the postoperative TPA and TPA increase was larger in dogs with fibular drill holes than without (P<.01) and in dogs with fibular fractures than without (P<.01). Conclusion: An unfilled fibular drill hole and increased body weight are risk factors for fibular fracture.     

Pre- and postoperative force plate analysis of dogs with experimentally transected cranial cruciate ligaments treated using tibial plateau leveling osteotomy

Objective— Quantitative and objective assessment of hindlimb kinetics after cranial cruciate ligament (CrCL) transection and subsequent stifle stabilization using the tibial plateau leveling osteotomy (TPLO) in normal dogs.
Study Design— In vivo experimental biomechanical evaluation.
Animals— Six healthy adult foxhounds.
Methods— Dogs were screened by orthopedic and radiographic examination before study entry. Force plate analysis of gait was measured before extirpation of the right CrCL and TPLO and again at 8 and 18 weeks after surgery.
Results— There was a significant decrease in peak vertical forces (PVFs) and vertical impulse (VI) of the treated hindlimb at 8 weeks when compared with preoperative and 18-week measurements. When compared with preoperative values, there was no significant difference in 18 week PVF and VI in dogs that had TPLO.
Conclusion— TPLO can restore kinetic measures of limb function at 18-weeks after surgery when compared with preoperative values after experimental transection of the CrCL in dogs.
Clinical Relevance— TPLO induces lameness that returns to near normal at 18 weeks. The severity and duration of lameness was similar to that reported for other experimental models of stifle instability repaired by different techniques.     

Change in tibial plateau angle after tibial plateau leveling osteotomy in dogs

OBJECTIVE: To determine the change in tibial plateau angle (TPA) during healing after tibial plateau leveling osteotomy (TPLO) performed for cranial cruciate ligament insufficiency in dogs and to examine factors that may be associated with the change. STUDY DESIGN: Retrospective study. STUDY POPULATION: One hundred and forty-nine canine stifles after TPLO procedure. METHODS: Records of dogs that had TPLO were reviewed. Patient age, weight, sex, breed, pre- and postoperative TPA, recheck TPA, time to recheck, type of implant used, and radiographic evidence of healing were analyzed. RESULTS: Mean time to recheck evaluation was 46 days (range, 28-65 days). Mean difference between immediate postoperative and recheck TPA measurements was 1.5 degrees (range, -3 to 9 degrees). Recheck TPA was a significantly greater (numerically higher) than immediate postoperative TPA (P<.0001). There was no significant effect of patient weight, type of plate used, or healing status of the osteotomy at the time of recheck. No correlation between pre- or postoperative TPA angles and change in TPA angle was detected. CONCLUSIONS: TPA changes during osteotomy healing after TPLO, but factors influencing this change were not identified. CLINICAL RELEVANCE: TPA may increase during healing after TPLO despite apparently adequate osteotomy fixation. The clinical relevance of this increase is unknown but is likely minimal.     

Proximal tibial intraarticular ostectomy for treatment of canine cranial cruciate ligament injury

OBJECTIVE: To report a technique for surgical alteration of the slope of the tibial plateau by a proximal tibial intraarticular ostectomy (PTIO) after injury to the canine cranial cruciate ligament (CCL) and to determine the outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Dogs (n=52) with CCL injury in 60 stifle joints. METHODS: CCL injury was treated by lateral stifle arthrotomy, removal of CCL remnants, and appropriate meniscal surgery. PTIO was performed to remove a wedge of bone from the proximal aspect of the tibia. The ostectomy site was reduced and stabilized using a bone plate and screws applied to the medial surface of the tibia as well as a craniocaudal positional screw. Dogs were evaluated at 6 weeks, 6, and 12 months by complication assessment, lameness scores, stifle range of motion (ROM), thigh circumference, radiographic assessment, degenerative joint disease (DJD) scores, and surgeon and owner evaluation of function. RESULTS: Lameness scores improved by 6 and 12 months in all but 1 dog. Thigh circumference and DJD were increased at 6 and 12 months. Complications occurred in 20% of dogs with all but 1 occurring perioperatively or within 6 weeks; most common were injury to the long digital extensor tendon (4 dogs) and plate failure (3); 2 other dogs required surgery to treat complications. Most owners (98%) reported that lameness had improved by 12 months; 90% were extremely or very satisfied with the procedure and 90% would have the same procedure performed on another dog. CONCLUSION: PTIO to level the tibial plateau provided a satisfactory clinical outcome in dogs >20 kg with CCL injury and the complication rate was similar to tibial plateau levelling osteotomy (TPLO). Stifle osteoarthritis continued to progress radiographically. CLINICAL RELEVANCE: PTIO represents an alternative to TPLO that does not require specialized surgical equipment.     

Combination tibial plateau leveling osteotomy and cranial closing wedge osteotomy of the tibia for the treatment of cranial cruciate ligament-deficient stifles with excessive tibial plateau angle

OBJECTIVE: To describe a surgical technique, and outcome, for treatment of cranial cruciate ligament (CrCL) deficient stifle joints with excessive tibial plateau angle (TPA) by combined tibial plateau leveling osteotomy and cranial closing wedge osteotomy (TPLO/CCWO). STUDY DESIGN: Retrospective clinical study. ANIMALS: Fifteen client-owned dogs (18 stifle joints). METHODS: Medical records of dogs that had TPLO/CCWO were reviewed. Pre- and postoperative TPA, CCWO technique, method of fixation and complications were recorded. In-hospital re-evaluation of limb function and length of time to radiographic healing was reviewed. Long-term outcome was assessed by owner telephone interview. RESULTS: Mean pre- and postoperative TPA was 42 degrees and 8 degrees, respectively. The Slocum biradial saw was used to create the CCWO in 4 stifle joints (mean postoperative TPA, 16 degrees) and a sagittal saw was used in 14 stifle joints (mean postoperative TPA, 5 degrees). Postoperative surgical complications were documented in 77.8% of cases; including patellar tendon thickening (61.1%), and implant loosening or breakage (27.8%), seroma formation (11.1%), and local irritation (11.1%). A second surgical procedure was performed in one-third of cases primarily to retrieve implants. Mean time to documented radiographic healing was 18 weeks. Final in-hospital re-evaluation of limb function (mean, 23 weeks postoperatively) was recorded as no lameness in 73.3% and mild lameness in 26.7%. All interviewed owners were satisfied with outcome and 90.9% reported marked improvement or a return to preinjury status. CONCLUSIONS: Long-term clinical outcome of TPLO/CCWO was very good in dogs with excessive TPA, with high owner satisfaction. Longer healing times and a higher complication rate were observed compared with TPLO alone. CLINICAL RELEVANCE: TPLO/CCWO of the tibia in stifle joints with excessive TPA allows for full correction of the TPA to 5 degrees without eliminating buttress support of the tibial tuberosity.     

In vitro comparison of tibial plateau leveling osteotomy with and without use of a tibial plateau leveling jig

OBJECTIVE: To evaluate the influence of a tibial plateau leveling jig on osteotomy orientation, fragment reduction, and postoperative tibial plateau angle (TPA) during tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: In vitro experimental study. ANIMALS: Large-breed canine cadavers (n=20). METHODS: TPLO was performed on 40 hindlimbs using 4 methods. Group 1: Jig; dogs in dorsal recumbency with the osteotomy parallel to the distal jig pin. Groups 2-4: No jig; dogs in lateral recumbency with the osteotomy in a vertical orientation (group 2: tibia parallel to the table top; group 3: controlled superimposition of the femoral condyles; group 4: internal rotation of the tibia). Postoperative TPA, fragment reduction, and osteotomy orientation relative to the tibial plateau were compared. Positive or negative values denoted deviation from parallel relative to the tibial plateau. RESULTS: Postoperative TPA, fragment reduction, and proximodistal osteotomy orientation were not significantly different between groups. Craniocaudal osteotomy orientation was significantly different (P<.005) from the tibial plateau. Median deviations were -4.0 degrees (group 1), 11.8 degrees (group 2), 11.2 degrees (group 3), and 0.2 degrees (group 4). Group 1 was not significantly different from group 4. CONCLUSIONS: A jig is not essential for osteotomy orientation, tibial plateau rotation, or fragment reduction. Comparable results were achieved performing a vertical osteotomy with the tibia slightly internally rotated (10 degrees -15 degrees) and parallel to the table surface. CLINICAL RELEVANCE: TPLO without use of a jig reduces surgical trauma, is less time consuming, and reduces cost.     

Comparison of two doses of recombinant human bone morphogenetic protein in absorbable collagen sponges for bone healing in dogs

OBJECTIVE: To determine the effects of 2 doses of recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge (rhBMP-2/ACS) on bone healing in dogs. ANIMALS: 27 adult dogs. PROCEDURES: Dogs underwent a mid-diaphyseal (1-mm) tibial osteotomy (stabilized with external skeletal fixation) and received an ACS containing 0.28 mg (0.2 mg/mL) or 0.56 mg (0.4 mg/mL) of rhBMP-2 or no treatment (control dogs). All dogs were examined daily; bone healing was assessed via radiography and subjective lameness evaluation every 2 weeks. After euthanasia at 8 weeks, tibiae were evaluated biomechanically and histologically. RESULTS: Control dogs required antimicrobial treatment for pin-site-related complications more frequently than did rhBMP-2/ACS-treated dogs. At 4 and 6 weeks, weight bearing was greater in dogs treated with rhBMP-2/ACS (0.2 mg/mL) than in control dogs, albeit not significantly. Compared with control treatment, both doses of rhBMP-2/ACS accelerated osteotomy healing at 4, 6, and 8 weeks, and the 0.2 mg/mL dose enhanced healing at 2 weeks; healing at 6 weeks was greater for the lower-dose treatment than for the higher-dose treatment. Histologically, healing at 8 weeks was significantly improved for both rhBMP-2/ACS treatments, compared with control treatment. Among groups, biomechanical variables did not differ, although less osteotomy-site failures occurred in rhBMP-2/ACS-treated groups. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs that underwent tibial osteotomy, rhBMP-2/ACS (0.2 mg/mL) appeared to accelerate bone healing and reduce lameness (compared with control treatment) and apparently augmented bone healing more than rhBMP-2/ACS (0.4 mg/mL). Compared with control dogs, rhBMP-2/ACS-treated dogs required antimicrobial treatments less frequently.     

The effect of cancellous autograft and novel plate design on radiographic healing and postoperative complications in tibial tuberosity advancement for cranial cruciate-deficient canine stifles

Objective: To assess the effect of autogenous cancellous bone graft (autograft) and novel plate use on radiographic healing and complications in tibial tuberosity advancement (TTA) for treatment of cranial cruciate ligament (CrCL)‐deficient stifles in dogs. Study Design: Prospective clinical study. Animals: Consecutive dogs (n=125) with unilateral CrCL‐deficient stifles. Methods: Four treatment groups: CPG, conventional plate with autograft; CPNG, conventional plate without autograft; NPG, novel plate with autograft; NPNG, novel plate without autograft were studied. Radiographs from 60 dogs were scored for healing at 6 and 10 weeks postoperatively; all 125 dogs were assessed for radiographic complications. Variables evaluated for relationship with healing scores and radiographic complications were age, weight, sex, cage and plate size, implant type, and graft use. Results: Dogs with autograft had overall higher healing scores at 6 and 10 weeks. Radiographic complications occurred in 13 dogs (12 minor, 1 major), and were not influenced by graft or novel plate use. Conclusion: Autograft increases healing scores, but was not found to have a significant impact on the rate of complications in TTA. The novel plate was not found to have healing scores or radiographic complication rates significantly different from the conventional plate design.     

Biomechanical Comparison of Two Alternative Tibial Plateau Leveling Osteotomy Plates with the Original Standard in an Axially Loaded Gap Model: An In Vitro Study

Objective— To compare the axial compression stiffness of osteotomized canine tibiae stabilized with Slocum, Securos, or Synthes plates after a tibial plateau leveling osteotomy (TPLO) procedure. Study Design— In vitro, paired comparison of cadaveric tibial constructs subjected to mechanical testing under an axial load. Sample Population— Canine tibiae (n=16 pairs) from skeletally mature male and female dogs of various breeds (18–55 kg). Methods— Tibial pairs (n=16) were randomly assigned to 1 of 2 study cohorts (n=8 pairs/cohort): cohort 1, tibial osteotomy stabilization with a Slocum or a Securos plate, or cohort 2, tibial osteotomy stabilization with a Slocum or a Synthes plate. One tibia from each pair was stabilized with 1 of each plate design assigned to the cohort after TPLO. A 3.2 mm osteotomy gap was maintained during plate application in all constructs. Load and axial displacement were recorded while constructs were loaded to 2000 N in axial compression. Failure loads were not reported because no distinct yield point or failure point was evident within the load range for many specimens. Failure modes were recorded for each construct, and photographs of typical failures were obtained. Stiffness (N/mm) was calculated from load–displacement curves. Paired comparisons of mean stiffness were performed within study groups using a paired t‐test. Significance was set at P<.05. Results— The mean construct stiffnesses for the Slocum (383±183 N/mm) and Securos (258±64.1 N/mm) constructs were not significantly different (P=.164; power=0.566). The mean construct stiffness for the Synthes constructs (486±91.0 N/mm) was significantly greater than that of the Slocum constructs (400±117 N/mm); P=.0468. Modes of failure for the Slocum (16/16) and Securos (8/8) constructs included plastic deformation of the implant with valgus deformity combined with fibular luxation (2/16 Slocum; 1/8 Securos) or fibular fracture (2/16 Slocum; 4/8 Securos). Most Synthes constructs underwent elastic deformation (7/8). One Synthes construct fractured in the saggital plane through the tibial plateau depression at the point of load application. Conclusions— The Slocum and Securos plate/tibia construct have similar stiffness, whereas the Synthes/tibia constructs are significantly stiffer than the Slocum/tibia constructs. Modes of fixation failure observed in this model were consistent with TPLO fixation failures observed clinically. Clinical relevance— Construct stiffness in axial load varies with implant type. Implants that confer higher stiffness to the construct may result in greater fixation stability in tibial metaphyseal osteotomies.     

Risk Factors Associated with Fibular Fracture After Tibial Plateau Leveling Osteotomy

Objective— To determine the incidence of, and risk factors for, fibular fracture after tibial plateau leveling osteotomy (TPLO) in dogs.
Study Design— Case series.
Sample Population— TPLO (n=168) on 142 dogs.
Methods— Medical records (January 2006–September 2007) and radiographs of all dogs that had TPLO were reviewed. Data retrieved were breed, sex, age, weight, type of plate, use of a jig, time to recheck, preoperative tibial plateau angle (TPA), immediate postoperative TPA, and presence or absence of fibular fracture.
Results— Fibular fractures occurred in 5.4% TPLOs. Body weight, change in TPA, and preoperative TPA were significantly higher in dogs with fibular fracture. TPLO without use of a jig was significantly associated with fibular fracture. Age, postoperative TPA, and plate type were not significantly associated with fibular fracture.
Conclusions— Fibular fracture is uncommon after TPLO. Risk factors are increased body weight, greater preoperative TPA, greater change in TPA, and TPLO performed without a jig. All fractures occurred during convalescence.
Clinical Relevance— Owners should be warned of potential complications and risk factors associated for fibular fracture after TPLO.     

Long-term radiographic comparison of tibial plateau leveling osteotomy versus extracapsular stabilization for cranial cruciate ligament rupture in the dog

OBJECTIVE: Comparison of 2 methods of surgical management of cranial cruciate ligament (CCL) injury in large-breed dogs using a radiographic osteoarthrosis (OA) scoring system. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n=66). METHODS: Radiographs were evaluated from dogs weighing >/=22.7 kg, with surgical management of CCL rupture using extracapsular repair (ECR) or tibial plateau leveling osteotomy (TPLO). Radiographs were taken immediately before surgery and >/=12 months later. An OA score was assigned to each set of radiographs taken at the preoperative and final examinations by evaluating 32 specific features of stifle OA. The difference between preoperative and final OA scores were subtracted and 2 final score categories of a change 5 were created. A logistic regression model was used to evaluate the effect of right versus left pelvic limb, age, preoperative weight, postoperative weight, days from surgery until final radiographic recheck, cranial cruciate status at surgery, medial meniscus status at surgery, and ECR versus TPLO. RESULTS: The ECR group had 27 stifles (22 dogs) and the TPLO group had 52 stifles (44 dogs). ECR dogs had a preoperative weight of 33.4+/-9.3 kg (range 22.7-54.1 kg) and a preoperative OA score of 13.0+/-8.4 (range 1-34) compared with TPLO dogs that had a preoperative weight of 38.9+/-9.1 kg (range 25-63.9 kg) and preoperative OA score of 15.9+/-8.4 (range 4-44). Postoperative weights for ECR and TPLO dogs were 33.6+/-9 kg (range 21.8-54.6 kg) and 39.4+/-10.1 kg (range 24-72 kg), respectively. Final OA scores were: ECR dogs, 26.3+/-10.8 (range, 10-54); TPLO dogs, 23.3+/-9.5 (range, 12-50). Dogs with a final change in OA score of >/=6 were 5.78 times more likely to have had ECR compared with those that had TPLO as stabilization procedure (odds ratio=5.78; Log-likelihood test P-value=.025). Other dependent variables were not significant. CONCLUSIONS: Based on logistic regression analysis, dogs with larger OA score differences were 5.78 times more likely to have had ECR than TPLO. CLINICAL RELEVANCE: Prospective, randomized surgical trials with pre-defined objective measures would be required to further evaluate the clinical importance of these preliminary findings which suggest that TPLO may help stabilize the cranial tibial thrust as originally proposed.     

Ex Vivo Evaluation of the Effect of Tibial Plateau Osteotomy on the Proximal Tibial Soft Tissue Envelope With and Without the Use of Protective Gauze Sponges

Objective— To investigate the effect of tibial plateau leveling osteotomy (TPLO) on the proximal tibial soft tissue envelope with and without use of protective gauze sponges, and to determine whether the action of an oscillating saw blade on the gauze sponges would result in retention of particulate cotton debris. Study Design— Cadaveric study. Animals— Medium to large breed dog cadavers (n=10; 20 pelvic limbs). Methods— TPLO was performed using the currently recommended technique involving dissection of the proximal tibial soft tissue envelope and its protection using cotton gauze sponges. In paired limbs, the procedure was repeated but no attempt was made to retract and protect the proximal tibial soft tissue envelope. Damage to the soft tissue envelope and presence of gross particulate cotton debris were investigated by direct observation and photographic analysis. Presence of microscopic cotton debris was investigated using light microscopic analysis of wound lavage fluid. Results— No soft‐tissue trauma was found in gauze sponge‐protected specimens. When protective gauze sponges were not used, full‐thickness (sagittal plane) lacerations to the caudoproximal tibial muscle group occurred in all specimens with a mean craniocaudal width of 9.5 mm (range 2–12 mm). The cranial tibial muscle was traumatized in only 1 specimen without protective gauze sponges. Trauma to the popliteal vessels was not identified in any specimen. No gross cotton debris was identified, but microscopic cotton fibers (diameter, 7–35 μm) were identified in lavage fluid from all gauze sponge‐protected specimens. Conclusions— Use of protective gauze sponges is effective in protecting the proximal tibial soft tissue envelope from an oscillating TPLO saw blade, but results in retention of microscopic cotton particulate debris within the operative site. Significant soft tissue trauma is seen only in the caudoproximal tibial muscle group if protective gauze sponges are not used. Clinical Relevance— Retraction and protection of the caudoproximal tibial soft tissue envelope is recommended during TPLO; however, to prevent retention of microscopic particulate cotton debris, alternatives to cotton gauze sponges should be considered as protective devices.     

Complications with and owner assessment of the outcome of tibial plateau leveling osteotomy for treatment of cranial cruciate ligament rupture in dogs: 193 cases (1997-2001)

OBJECTIVE: To identify complications associated with tibial plateau leveling osteotomy (TPLO) for treatment of cranial cruciate ligament rupture in dogs and assess owner perceptions of outcome. DESIGN: Retrospective study. ANIMALS: 193 dogs that underwent unilateral or bilateral TPLO (253 TPLOs total) between November 1997 and March 2001. PROCEDURE: Complications associated with the surgical procedure were recorded. A questionnaire was sent to owners of all dogs to assess their perceptions of outcome. RESULTS: Complications were identified in 47 of the 193 (24.4%) dogs and in association with 52 of the 253 (20.6%) TPLOs. Dogs that underwent bilateral TPLOs during a single anesthetic episode had a higher complication rate than did dogs that underwent unilateral TPLO and dogs that underwent bilateral TPLOs during separate anesthetic episodes. Body weight, surgery time, whether a meniscal release or meniscectomy was performed, and extent of cruciate ligament damage were not associated with whether complications occurred. One hundred forty-one of 151 (93%) owners who responded to the questionnaire were satisfied with the outcome of the surgery. Assessments of outcome were not significantly different between owners of dogs that had complications and owners of dogs that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that complications developed in approximately 25% of dogs undergoing TPLO for treatment of a cranial cruciate ligament injury but that most complications responded to appropriate treatment, and development of complications did not affect owner assessments of outcome. There was a higher incidence of complications when bilateral TPLOs were performed during a single anesthetic episode.     

Comparison of bone healing,as assessed by computed tomography,following tibial tuberosity advancement in dogs with and without autogenous cancellous bone grafts

Abstract

AIMS: To objectively compare measures of bone healing, using computed tomography (CT) in dogs following bilateral tibial tuberosity advancement (TTA), between tibiae treated with and without autogenous cancellous bone grafts.

METHODS: Ten dogs with bilateral cranial cruciate ligament disease requiring surgical stabilisation were prospectively recruited to undergo single-session bilateral TTA, with only one, randomly assigned, tibia receiving bone graft in the osteotomy deficit. Bone healing at the osteotomy site was assessed using CT performed 38–70 days post-operatively. CT images were evaluated using both objective measurements of osseous bridging and subjective evaluation by six radiologists. Repeated measures ANOVA was used to compare the objective outcomes between the grafted and non-grafted tibiae.

RESULTS: The mean percentage of the osteotomy deficit bridged at the lateral cortex was greater in grafted (77.6, SD 35.2%) compared to non-grafted (63.0, SD 36.5%) tibiae (p=0.001), but did not differ at the medial cortex (p=0.1). The mean minimum callus width was greater in grafted (7.2, SD 3.3 mm) compared to non-grafted (3.6, SD 2.9 mm) tibiae (p<0.001). There was no difference in mean attenuation (measured in Hounsfield units) of the callus between grafted and non-grafted tibiae (p=0.5). The grafted tibia was deemed to have superior bone healing in 50/60 subjective assessments made by radiologists.

CONCLUSIONS: Superior osseous bridging was detected by CT analysis following TTA using autogenous cancellous bone grafts compared with no graft. This was shown by greater bridging percentage at the lateral cortex and formation of a broader callus. Qualitative assessments made by six radiologists also supported the conclusion that bone healing was improved by use of autogenous cancellous bone graft. CT was a useful method for assessing evidence of bone healing following TTA.

CLINICAL RELEVANCE: These findings justify the application of autogenous cancellous bone graft to augment healing following TTA in dogs.     

Kinematic gait analysis of the hind limb after tibial plateau levelling osteotomy and cranial tibial wedge osteotomy in ten dogs

This study identifies and compares the kinematic gait changes occurring in tibial plateau levelling osteotomy (TPLO) and cranial tibial wedge osteotomy (CTWO) limbs after transection of the cranial cruciate ligament (CrCL). Ten, healthy, adult beagle dogs were assigned to TPLO (five dogs) and CTWO (five dogs) groups. Hind limb kinematics were assessed, while dogs were trotted at speeds ranging from 2.0 to 2.3 m/s. The animals were evaluated preoperatively (prior to TPLO and CTWO surgery) and at both 8 and 12 weeks after surgery. Two-dimensional evaluation was synchronized to obtain the three-dimensional coordinates using the APAS motion analysis software. Gait patterns were assessed by measuring stifle, tibiotarsal joint angles and stifle joints angular velocity. Stifle and tibiotarsal joint functions were not affected by TPLO surgery, but stifle and tibiotarsal joint angles were changed, following CTWO surgery, compared with their preoperative values. The angular velocity patterns of CTWO were characterized by increased stifle joint extension velocity from the middle to end swing phase and decrease in the peak velocities (flexion) during swing phase. None of these changes was observed in the stance phase after the CTWO surgery. These kinematic results showed that dogs that underwent a CTWO procedure were more likely to have significantly hyperextended gait patterns of the swing phase postoperatively than the dogs that had a TPLO procedure for repair of a ruptured CrCL.