Force plate gait analysis to assess limb function after tibial tuberosity advancement in dogs with cranial cruciate ligament disease

OBJECTIVE: To assess functional outcome in dogs with cranial cruciate ligament (CrCL) disease after tibial tuberosity advancement (TTA) using force plate gait analysis, and to evaluate parameters potentially influencing outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Consecutive clinical patients (n = 37) with CrCL-deficient stifles (n = 40). METHODS: The stifle joints were examined arthroscopically prior to TTA. Meniscal release was not performed if the medial meniscus was intact. Open medial arthrotomy and partial meniscectomy were performed in the presence of meniscal tears. Vertical ground reaction forces were measured preoperatively and at follow-up examinations four to 16 months postoperatively (mean: 5.9 months). The ground reaction forces of a group of 65 healthy dogs were used for the comparison. The potential effects of clinical parameters on functional outcome were evaluated statistically. RESULTS: Complete CrCL rupture was identified in 28 joints, and partial CrCL rupture in 12 joints. The medial meniscus was damaged in 21 stifles. Vertical ground reaction forces were significantly higher at follow-up (P < 0.01), but remained significantly lower than those of control dogs (P < 0.01). Complications were identified in 25% of joints, and the dogs with complications had significantly lower peak vertical forces at follow-up than the dogs without complications (P = 0.04). Other clinical parameters did not influence outcome. CONCLUSIONS: Tibial tuberosity advancement significantly improved limb function in dogs with CrCL disease, but did not result in complete return to function. Complications adversely affected functional outcome. CLINICAL SIGNIFICANCE: A return to a function of approximately 90% of normal can be expected in dogs with CrCL disease undergoing TTA.     

Effect of tibial tuberosity advancement on cranial tibial subluxation in canine cranial cruciate-deficient stifle joints: an in vitro experimental study

OBJECTIVE: To evaluate the effect of tibial tuberosity advancement (TTA) on tibiofemoral shear force as reflected by measurement of cranial tibial subluxation (CTS) and patella tendon angle (PTA) in the canine cranial cruciate ligament (CrCL) deficient stifle joint. STUDY DESIGN: In vitro cadaver study. ANIMALS: Canine cadaveric hind limbs (n=10). METHODS: CTS and PTA were evaluated from lateral radiographic projections in axially loaded intact CrCL stifle joints, after transection of the CrCL, at a maximally advanced tibial tuberosity position, and at a critical point position. A custom-designed hinge plate allowed alteration of the tibia to tibial tuberosity distance (Ti-TT) under axial load. Digitized radiographic images were used to quantify CTS, PTA, and Ti-TT. Comparisons within groups were made using 1-way repeated measures ANOVA. A post hoc Tukey's HSD test was used to determine post-ANOVA pair-wise comparison within these groups. Significance was set at a value of P<.05. RESULTS: CTS occurred after CrCL transection, which was significantly different from the intact position (P<.01). Subsequent stability of the stifle joint was obtained by advancing the tibial tuberosity. In the maximally advanced tibial tuberosity position, caudal tibial thrust was generated resulting in caudal tibial subluxation that was significantly different from the transected CrCL position (P<.01) and from the intact CrCL position (P<.01). Despite a stable joint, there was slight CTS at the critical point position, which was significantly different from the intact CrCL position (P<.05). The PTA at the maximally advanced position was significantly different from the intact, critical point and reference 90 degrees PTAs (P<.01). The PTA at the critical point position was significantly different from the intact and maximally advanced tibial tuberosity PTAs (P<.01), but not different (P>.05) from the reference 90 degrees PTA. CONCLUSION: We demonstrated that advancement of the tibial tuberosity neutralized cranial tibial thrust, and converted cranial tibial thrust into caudal tibial thrust. Neutralization of tibiofemoral shear forces occurred at a PTA of 90.3+/-9.0 degrees. CLINICAL RELEVANCE: TTA can effectively change the magnitude and direction of the tibiofemoral shear force, and thus may be used to prevent craniotibial translation in a CrCL deficient stifle joint.     

Tibial tuberosity advancement for stabilization of the canine cranial cruciate ligament-deficient stifle joint: surgical technique, early results, and complications in 101 dogs

Objective— To describe the surgical technique, early results and complications of tibial tuberosity advancement (TTA) for treatment for cranial cruciate ligament (CrCL)-deficient stifle joints in dogs.
Study Design— Retrospective clinical study.
Animals— Dogs (n=101) with CrCL-deficient stifles (114).
Methods— Medical records of 101 dogs that had TTA were reviewed. Complications were recorded and separated into either major or minor complications based on the need for additional surgery. In-hospital re-evaluation of limb function and time to radiographic healing were reviewed. Further follow-up was obtained by telephone interview of owners.
Results— Complications occurred in 31.5% of the dogs (12.3% major, 19.3% minor). Major complications included subsequent meniscal tear, tibial fracture, implant failure, infection, lick granuloma, incisional trauma, and medial patellar luxation; all major complications were treated with successful outcomes. All but 2 minor complications resolved. The mean time to documented radiographic healing was 11.3 weeks. Final in-hospital re-evaluation of limb function (mean, 13.5 weeks), was recorded for 93 dogs with lameness categorized as none (74.5%), mild (23.5%), moderate (2%), and severe (1%). All but 2 owners interviewed were satisfied with outcome and 83.1% reported a marked improvement or a return to pre-injury status.
Conclusions— TTA is a procedure comparable with alternate methods of CrCL repair with expected good to excellent functional outcome.
Clinical Relevance— TTA procedure can be successfully used to obtain the dynamic stability of a CrCL-deficient stifle joint in dogs.     

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.     

Use of a TTA plate for correction of severe patella baja in a Chihuahua

A 7 yr old spayed female Chihuahua presented for right hind limb lameness and reduced stifle range of motion. Radiographs showed a marked patella baja of the right stifle and evidence of a previous surgery to correct a medial patellar luxation. A tibial tuberosity osteotomy was performed to allow proximal translation of the tibial tuberosity, which was stabilized with a tibial tuberosity advancement plate. Four weeks postoperatively, lameness and articular range of motion were improved, and the use of anti-inflammatory and analgesic medications was discontinued. The dog was still ambulating well and had no lameness 12 mo postsurgically.     

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.     

Effect of 9 mm tibial tuberosity advancement on cranial tibial translation in the canine cranial cruciate ligament-deficient stifle

Objective— To assess the effect of 9 mm tibial tuberosity advancement (TTA) on cranial tibial translation (CTT) in a cranial cruciate ligament (CCL)-deficient canine stifle model.
Study Design— In vitro cadaveric study.
Animals— Canine pelvic limbs (n=12).
Methods— Each stifle was placed in a jig at 135° with a simulated quadriceps force and tibial axial force. CTT distance was measured with the CCL intact (iCCL), transected (tCCL), and after performing TTA using a 9 mm cage.
Results— Mean CTT for iCCL was 0.42 mm, 1.58 mm after severing the CCL, and 1.06 mm post-TTA. The tCCL CTT measured without any quadriceps force was 2.59 mm. Differences between the intact and tCCL ( P <.0001) and tCCL and TTA ( P =.0003) were significant. The difference between the tCCL with and without the quadriceps force was not significant ( P =.0597).
Conclusions— These data confirm that TTA does reduce CTT in tCCL stifles in this model. The CTT noted was less than that noted clinically. The addition of a simulated quadriceps force to a CCL-deficient stifle before a TTA, by itself, may not significantly lessen CTT.
Clinical Relevance— Whereas this in vitro model demonstrated that TTA reduced CTT in canine stifles with CCL transected, the model limitations preclude extrapolation to the effect of TTA in a live dog.     

Tibial tuberosity advancement in 92 canine stifles: initial results,clinical outcome and owner evaluation

Objective To investigate the clinical outcomes, complications and owners' evaluation of the tibial tuberosity advancement (TTA) procedure in canine stifles. Methods A retrospective study of hospital records was performed to identify dogs diagnosed with partial or complete cranial cruciate ligament (CCL) rupture that had undergone TTA repair. Information obtained included signalment, period of lameness, surgical report, evidence of meniscal injury, postoperative recovery and peri-operative complications. Owners were asked to assess the long-term outcome. Results In a total of 72 dogs (median age, 6 years; median body weight, 34.8 kg), TTA was performed in 92 stifles. Twenty breeds were represented, with Labrador Retrievers and Rottweilers the most common. The period of lameness ranged from 3 days to 24 months. The median pre-operative lameness score was 3/4 and meniscal injury was present in 51 stifles. Minor complications occurred in 29% of cases. Major complications occurred in 6.5% of cases and consisted of meniscal injury and two tibial tuberosity fractures. All were successfully managed, with good limb function when subsequently assessed. In the owner evaluation, 96% reported moderate to great improvement postoperatively, with no lameness at rest and mild to no lameness after vigorous exercise. Conclusion Clinical outcome and owner evaluations in this case series indicate favourable results can be expected when CCL-deficient stifles are treated with TTA.     

Short-term and eight to 12 months results of a tibial tuberosity advancement as treatment of canine cranial cruciate ligament damage

OBJECTIVE: To describe the perioperative complications and the six weeks and eight to 12 months outcome of cases of canine cranial cruciate ligament damage treated with a tibial tuberosity advancement. METHODS: The medical records including the six weeks' postoperative re-evaluation and radiographs of dogs with a tibial tuberosity advancement (70 operated stifles) were analysed regarding the short-term outcome and the recorded complications. A questionnaire for the evaluation of the eight to 12 months outcome was sent to the owners and the answers tabulated. RESULTS: The complication rate was comparable with previous reports of cranial cruciate ligament rupture treated with a tibial tuberosity advancement or a tibial plateau leveling osteotomy (TPLO). The most frequent complication was a symptomatic late secondary meniscal damage in six cases (8.5 per cent). These cases were successfully treated with a partial meniscectomy during a minimal invasive procedure. The six-week re-evaluation showed advanced healing of the tibial crest osteotomies in 94 per cent of the cases and a significant reduction of the lameness in all dogs. Eighty-three per cent of the owners reported that their dogs are never lame or only after heavy exercise eight to 12 months after the tibial tuberosity advancement procedure. Sixty-five per cent of the owners stated the overall treatment to be excellent, 28 per cent good. CLINICAL SIGNIFICANCE: The six weeks' follow-up examination and the questionnaire revealed results of the tibial tuberosity advancement comparable to previously published studies, stating that the lameness and the activity level of the patients with cranial cruciate ligament disease greatly improved after the tibial tuberosity advancement.     

Effect of Tibial Tuberosity Advancement on Femorotibial Contact Mechanics and Stifle Kinematics

Objective— To evaluate the effects of tibial tuberosity advancement (TTA) on femorotibial contact mechanics and 3-dimensional kinematics in cranial cruciate ligament (CrCL)-deficient stifles of dogs.
Study Design— In vitro biomechanical study.
Animals— Unpaired pelvic limbs from 8 dogs, weighing 28–35 kg.
Methods— Digital pressure sensors placed subjacent to the menisci were used to measure femorotibial contact force, contact area, peak and mean contact pressure, and peak pressure location with the limb under an axial load of 30% body weight and a stifle angle of 135°. Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TTA-treated conditions. Repeated measures analysis of variance with a Tukey post hoc test ( P <.05) was used for statistical comparison.
Results— Significant disturbances to all measured contact mechanic parameters were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and internal tibial rotation in the CrCL-deficient stifle. No significant differences in any contact mechanic and kinematic parameters were detected between normal and TTA-treated stifles.
Conclusion— TTA eliminates craniocaudal stifle instability during simulated weight-bearing and concurrently restores femorotibial contact mechanics to normal.
Clinical Relevance— TTA may mitigate the progression of stifle osteoarthritis in dogs afflicted with CrCL insufficiency by eliminating cranial tibial thrust while preserving the normal orientation of the proximal tibial articulating surface.     

Reverse TPLO for asymmetrical ‐premature closure of the proximal tibial physis in a dog

A 4 · 5‐month‐old, 13 · 8 kg, female neutered mixed breed dog was presented for evaluation of acute non‐weight bearing right pelvic limb lameness. Radiographs revealed a tibial tuberosity avulsion fracture for which open reduction/internal fixation was performed. Asymmetrical premature closure of the cranial aspect of the proximal tibial physis ensued with a tibial plateau angle of ?12°. Abnormal stifle biomechanics resulted in lameness and caudal cruciate ligament fraying. Tibial plateau ‐levelling osteotomy was performed in standard fashion with the exception that the proximal tibial ‐fragment was rotated cranioproximally to increase the tibial plateau angle from ?12° to +5° (reverse tibial ‐plateau levelling osteotomy). Normal healing and resolution of lameness followed and the dog remained ‐clinically healthy 2 years postoperatively. This case report demonstrates that any change in proximal tibial anatomy, whether traumatic, iatrogenic or with therapeutic intent, can cause altered stifle biomechanics and should not be underestimated. Surgical management through corrective ‐osteotomy can be used to restore adequate function.     

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.     

Osteosarcoma at the site of titanium orthopaedic implants in a dog

An Alaskan Malamute underwent unilateral tibial tuberosity advancement (TTA) surgery to stabilise a stifle joint with a deficient cranial cruciate ligament. The dog made an excellent recovery with no postoperative complications, until 20 months post-surgery when he presented with acute onset ipsilateral pelvic limb lameness. Osteosarcoma (OSA) was diagnosed adjacent to the titanium implants. Currently, there is a paucity of information on the epidemiology of OSA adjacent to orthopaedic implants in canine patients. The clinical, radiological and pathological findings of this case of periprosthetic OSA, and a potential causal relationship between titanium implants and bone neoplasia, are discussed.     

Tibial Plateau Leveling Osteotomy or Tibial Tuberosity Advancement?

Objective— To review the proposed biomechanical basis of the tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA) and recommendations for these techniques.
Study Design— Literature review.
Methods— Literature search through Ovid Medline Plus, Pub Med, CAB Abstracts, and conference proceedings abstracts (August 1983 to March 2008).
Results— TPLO and TTA stabilize the cranial cruciate ligament (CrCL) deficient stifle joint neutralizing tibiofemoral shear forces by altering the geometry of the proximal aspect of the tibia. Stability is attained by placing the joint in a functionally greater flexion angle so that the patellar tendon angle (PTA) remains ≤90°. Both procedures target slightly differing endpoints, the significance of which is unknown. Many of the biomechanical variables investigated appear to favor the TTA; however, TPLO appears to have more clinical versatility. The clinical ramifications of these differences remain to be determined but the reported results for both procedures are comparable. Only the early results of these techniques have been reported, which is reflected in the relatively high number of complications associated with the early learning curve for both procedures.
Conclusions— There are many similarities between TPLO and TTA although it remains to be fully elucidated if either procedure is superior and under what conditions.
Clinical Relevance— TPLO and TTA are effective at returning dogs with a CrCL-deficient stifle joint to good limb function. Surgeon discretion and case selection drive selection of TPLO or TTA based mostly on anecdotal evidence and personal experience.     

Comparison of healing of the osteotomy gap after tibial tuberosity advancement with and without use of an autogenous cancellous bone graft

Objective: To evaluate and compare healing, with and without the use of bone graft, of the gap created during tibial tuberosity advancement (TTA). Study Design: Prospective study and case series. Animals: Dogs treated with TTA (n=67). Methods: Prospective study: Mediolateral radiographic projections (6 weeks and 4 months) after TTA without use of bone graft (group I, n=14) were compared with radiographs of consecutive TTA in which the gap was filled with autologous cancellous bone graft (group II, n=14). Two scoring techniques (A, B) were used. Score A was used to grade the overall osteotomy healing (0=no healing, 4=healed osteotomy). Score B evaluated, independently of each other, healing in 3 sites: proximal to the cage (B1), between cage and plate (B2), and distal to the plate (B3). Case series: nongrafted TTA (4–25 weeks, n=39) were evaluated for healing (Score A). Data was analyzed using t‐tests and ANOVA. Significance was set at P≤.05. Results: Prospective study: Score A, B2, and B3 showed no difference in healing between groups at 6.8 weeks and 4.2 months. Score B1 revealed, in both rechecks, a significantly higher density in group II. Case series: Radiographs at 11.59±5.99 weeks scored 3.3 (2–4). No healing related complications were observed. Conclusion: The osteotomy gap created during TTA healed within expected time regardless of bone graft use.     

Tibial tuberosity advancement for treatment of CrCL injury: complications and owner satisfaction

The purpose of this retrospective study of 171 dogs that underwent 193 tibial tuberosity advancement (TTA) surgeries was to describe complications and owner satisfaction associated with the procedure. Complications occurred in 21 cases (11%). Subsequent meniscal tear was the most common complication (10/193, 5.2%). Increasing body weight (P=0.02-0.04) and small cage size (P=0.06) were significantly associated with postsurgical complications. Ninety-two percent of owners were satisfied with the outcome of the TTA procedure, but only 84% stated that they would be willing to have the procedure performed again. The authors concluded that TTA had a complication rate and owner satisfaction similar to other tibial osteotomies for the surgical correction of cranial cruciate ligament disease.     

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.     

Comparison of tibial plateau angles in dogs with and without cranial cruciate ligament injuries

OBJECTIVE: To measure and compare tibial plateau angles (TPA) of dogs with cranial cruciate ligament (CrCL) injuries and dogs without CrCL injuries. DESIGN: Prospective study. ANIMALS: 87 dogs. PROCEDURE: Stifle joints were measured from lateral radiographic views to determine TPA in 3 groups: group-1 dogs had CrCL injuries, group-1a dogs, a subgroup of group 1, had 1 unaffected stifle joint, and group-2 dogs had no CrCL injuries. Age, sex, breed, body weight, limb injured, and TPA were recorded for each dog. RESULTS: 56 stifle joints were measured in group-1 dogs; mean TPA was 23.76 degrees , and mean age and weight were 5.7 years and 37.91 kg (83.4 lb), respectively. Fourteen stifle joints were measured in group-1a dogs; mean TPA was 24.71 degrees , and mean age and weight were 5.6 years and 38.06 kg (83.8 lb), respectively. Sixty stifle joints were measured in group-2 dogs; mean TPA was 18.10 degrees , and mean age and weight of these dogs were 4.83 years and 35.85 kg (79 lb), respectively. The most common breeds included Labrador Retriever, Golden Retriever, and Rottweiler. The TPA of dogs in group 1 and group 1a were significantly greater than the TPA of dogs in group 2. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with CrCL injuries have a significantly greater TPA than dogs without CrCL injury. With further investigation, a normal TPA can be determined. In the future, TPA measurements may be used to screen dogs suspected of being susceptible to CrCL injury.     

Angle between the patellar ligament and tibial plateau in dogs with partial rupture of the cranial cruciate ligament

OBJECTIVE: To measure the angles between the patellar ligament and the tibial plateau and between the patellar ligament and the common tangent at the tibiofemoral contact point (TFCP) in stifle joints of dogs with partial rupture of the cranial cruciate ligament (CrCL) for comparison with data obtained for stifle joints in dogs with intact CrCLs. SAMPLE POPULATION: 60 stifle joints of 54 dogs with surgically confirmed partial CrCL rupture. PROCEDURES: Mediolateral radiographic views of the stifle joints were obtained, and the angles between the patellar ligament and the conventionally defined tibial plateau (angle gamma) and between the patellar ligament and the common tangent to the TFCP (angle alpha) were measured at incidental stifle joint flexion (angle beta) by 2 independent observers. Data underwent linear regression analysis and were compared with findings in joints of dogs without degenerative joint disease. RESULTS: In stifle joints of dogs with a partial rupture of the CrCL, angles gamma and alpha were 5 degrees and 2 degrees larger than each corresponding angle in healthy canine joints. At 100 degrees of flexion, the patellar ligament was perpendicular to the conventionally defined tibial plateau. At 110 degrees of flexion, the patellar ligament was perpendicular to the common tangent at the TFCP. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, stifle joints with partially ruptured CrCLs have marginally larger angles between the patellar ligament and the tibial plateau, compared with joints with intact CrCLs; at equivalent angles of flexion, comparatively greater shear force affects the CrCLs in stifle joints with partial CrCL ruptures.