Reconstruction of the Quadriceps Extensor Mechanism with a Calcaneal Tendon-Bone Allograft in a Dog with a Resorbed Tibial Tuberosity Fracture

A non-reducible tibial tuberosity fracture is a rare complication of tibial tuberosity transposition performed during correcting of medial patella luxation (MPL) in dogs. This condition severely disrupts the quadriceps extensor mechanism, leading to significant pelvic limb lameness. An 11-year-old, 1.8 kg spayed female Yorkshire Terrier sustained a comminuted left tibial tuberosity fracture during surgical correction of an MPL. Six months after surgery, the dog was markedly lame and unable to extend the left stifle. Radiographs revealed patella alta and resorption of the fragmented tibial tuberosity. A composite frozen allogeneic calcaneal tendon-bone block was utilized to reconstruct the tibial tuberosity and reattach the patellar ligament. Initial postoperative radiographs confirmed restoration of a normal patellar ligament to patella length ratio (1.42). Both the allogeneic bone used for tibial tuberosity reconstruction and the tendon used to reattach the patellar ligament were successfully integrated. The dog regained satisfactory limb function without recurrence of patella luxation, as reported by the owners 29 months postoperatively. The use of a calcaneal tendon-bone allograft effectively restored the functional integrity of the quadriceps extensor mechanism, providing a viable option for addressing quadriceps insufficiency resulting from the loss of the osseous tibial insertion.

Effects of the Direction of Two Kirschner Wires on Combined Tibial Plateau Leveling Osteotomy and Tibial Tuberosity Transposition in Miniature Breed Dogs: An Ex Vivo Study

This study evaluates the impact of Kirschner wire (K-wire) insertion direction on the biomechanical properties of combined tibial plateau leveling osteotomy (TPLO) and tibial tuberosity transposition (TTT) procedures in small-breed dogs with cranial cruciate ligament rupture and medial patella luxation. Twenty-one cadaveric tibiae were divided into two groups; the specimens were divided into two groups; one underwent TPLO-TTT with a proximal pin placement (Group TTP), and the other received TPLO-TTT with a distal pin placement (Group TTD). For both pin placements, two additional subgroups were formed: one with a 0.56 mm tension band (Groups TTP0.56 and TTD0.56) and the other with a 0.76 mm tension band (Groups TTP0.76 and TTD0.76). The tensile force was applied, and failure load and mode were recorded. The distal pin direction in Group TTD0.56 exhibited a significantly higher mean failure load (380.1 N) compared to the proximal pin direction in Group TTP0.56 (302.2 N, p = 0.028). No significant differences were observed among the other groups. This study concludes that distal pin placement can provide similar or improved mechanical stability in cases with limited space for proximal pin placement during combined TPLO and TTT procedures.

Biomechanical evaluation of a fixation technique with a modified hemicerclage for tibial tuberosity transposition: an ex vivo cadaveric study

Objectives

(1) To determine stiffness, load at failure, and mode of failure of a novel fixation method with a tension modified-hemicerclage (MH) for tibial tuberosity transposition, and (2) to compare the biomechanical properties of this novel fixation technique to 2 pins (2Pins) and 2 pins and tension band wire fixation (2Pins + TBW).

Study design

Thirty cadaveric stifles from dogs between 5.2 and 13.1 kg were assigned to 3 treatment groups: Group 1: fixation technique with MH; Group 2: 2Pins; Group 3: 2Pins + TBW. Biomechanical testing was performed with the tibia positioned at an angle of 135° relative to vertical position. Tensile force was applied to the patellar ligament until catastrophic failure was observed. The mode of failure, the load at failure, and the stiffness were compared among treatment groups.

Results

The mean stiffness of the novel fixation (38.1 N/mm ± 7.1) and the 2Pins + TBW (40.2 N/mm ± 9.3) were greater than the 2Pins (26.7 N/mm ± 6.7). There was no significant difference between the novel fixation technique and 2Pins + TBW in stiffness and maximum load to failure. The 2Pins (284.3 N ± 70.5) failed at a significantly lower load than the tension modified-hemicerclage (555.7 N ± 225.9 N) and 2Pins + TBW (715.3 N ± 339.8 N).

Conclusion

A fixation technique using a modified hemicerclage had the same strength and stiffness as the 2Pins + TBW and was stronger and stiffer than the 2 Pins technique in a cadaveric model.

Outcome of surgical correction of medial patellar luxation in dogs weighing less than 10 kg

BACKGROUND

Various trochleoplasty techniques, including trochlear wedge recession (TWR) and trochlear block recession (TBR), are used to treat dogs with medial patellar luxation (MPL). However, the objective outcomes of these surgical procedures are underreported.

METHODS

Medical records were obtained for dogs weighing less than 10 kg that underwent either TWR or TBR and tibial tuberosity transposition to address grade I-III MPL. Long-term (at least 1 year after the last procedure) follow-up included orthopaedic and radiographic examinations, such as osteoarthritis score (OAS), ground reaction force (GRF) analysis and canine brief pain inventory (CBPI).

RESULTS

Overall, 20 dogs (26 stifles) were followed up in the long term. Minor postoperative complications, medial patellar reluxation (MPR) and intermittent lameness occurred in 46.15%, 19.23% and 15% of the dogs, respectively. MPR occurred only in TWR-treated stifles, while mean OAS increased in all groups. Using the CBPI, the owners perceived an excellent or very good outcome in 95% of dogs.

LIMITATIONS

The limitations of the study include its retrospective observational nature, a lack of randomisation and a small sample size.

CONCLUSION

Surgical treatment resulted in a favourable outcome. GRF analysis could detect subtle differences in weight bearing in dogs treated for MPL, which might not be apparent clinically. There might be a higher risk for reluxation for TWR. However, a larger-scale prospective study would be required to find which treatment is superior.

Trochlear Ridge Prostheses for Reshaping Femoral Trochlear Ridges in Dogs with Patellar Luxation

OBJECTIVES

 To describe the implant characteristics and surgical application of a custom-made trochlear ridge prosthesis (TRP) and to report clinical outcomes in dogs affected by patellar luxation treated with TRP.

STUDY DESIGN

 Dogs affected by patellar luxation underwent computed tomography. A specific canine bone anatomical replica, a cutting guide, and a TRP were designed and provided for surgery. Surgical records, clinical and radiographic reassessments, complications, pre- and postoperative lameness, type and degree of patellar luxation, and TRP and patellar position after surgery were reviewed. Clinical outcomes were defined as full, acceptable, or unacceptable function.

RESULTS

 The TRP was implanted in 60 femoral trochleae: 48 unilateral and 12 bilateral. Successful correction of patellar luxation was achieved in 59/60 cases. TRP was applied with other surgical techniques in 36/60 of the cases and as the only surgical procedure in 24/60 cases. Overall, three complications were observed: two minor and one major (patellar luxation recurrence). Neither implant loosening nor infection was observed. The mean radiographic follow-up was 3.8 months. At the time of the final follow-up, 57/60 cases were scored as fully functional.

CONCLUSION

 The TRP application either alone or in combination with other surgical techniques allowed for correction of patellar luxation and improvement in preoperative lameness with nominal complications. TRP could represent a potentially reliable alternative to trochleoplasty.

A modified triple tibial osteotomy for management of canine cranial cruciate ligament disease: retrospective assessment of 309 procedures (2017-2020)

CASE HISTORY

Medical records from a single referral hospital (Animal Referral Hospital, Sinnamon Park, Australia) of dogs treated with modified triple tibial osteotomy (TTO) for management of cranial cruciate ligament (CrCL) disease from June 2017 to June 2020 were reviewed. Modifications to the originally described TTO procedure included a modified wedge angle calculation and performing the tibial osteotomies without the use of pre-drilled guide holes.

CLINICAL FINDINGS

A total of 253 dogs met the inclusion criteria. Two dogs were excluded, leaving 251 dogs that had undergone 309 procedures for assessment, and data from these, including complications, were reviewed. Complete, partial competent, and partial incompetent rupture of the cranial cruciate ligament was identified in 202/309 (65.4%), 79/309 (25.6%), and 28/309 (9.1%) stifles, respectively. Medial meniscal injury was identified in 207/309 (67.0%) stifles at the time of initial surgery.

TREATMENT AND OUTCOME

Fifty-eight dogs had bilateral procedures, including both single-session and staged surgeries, and 48 of these were available for analyses. The modifications to the TTO procedure described herein resulted in a median wedge angle of 21° and a median post-operative tibial plateau angle of 5.8°. Tibial compression testing following surgery indicated elimination of cranial tibial thrust in all stifles in this series. The most common intra-operative complication was tibial tuberosity fracture (15/309; 4.9%). Minor post-operative complications occurred in 37/309 (12.0%) procedures, with infection being the most common (27/309; 8.7%). Major post-operative complications occurred in 9/309 (2.9%) procedures. The intra- and post-operative complication rates for dogs undergoing bilateral single-session TTO were both 8.3% (2/24). The intra- and post-operative complication rates for dogs undergoing bilateral staged TTO were both 4.2% (1/24). The low number of complications for both the bilateral single-session and bilateral staged TTO groups precluded statistical analysis. All complications resolved uneventfully as determined by the attending surgeon.

CLINICAL RELEVANCE

The modified TTO technique described here was safe and effective for the management of canine CrCL disease in the dogs included in the case series. Findings of this study suggest that, with careful case selection, the modified TTO may be performed as a bilateral single-session procedure in dogs with concurrent bilateral cranial cruciate ligament disease. Future studies analysing the effects of these modifications on stifle biomechanics would be beneficial.

ABBREVIATIONS

CrCL: Cranial cruciate ligament; SSI: Surgical site infection; TPA: Tibial plateau angle; TPLO: Tibial plateau levelling osteotomy; TTA: Tibial tuberosity advancement; TTO: Triple tibial osteotomy.

Stifle arthrodesis in a feline pelvic limb amputee

Case summary

A domestic shorthair cat presented to the Animal Referral Hospital (Brisbane, Australia) after having the left pelvic limb incorrectly amputated. The cat was unable to ambulate on the remaining right pelvic limb due to a chronically subluxated stifle. A stifle arthrodesis was performed on the right pelvic limb to manage the injury. Follow-up radiographs performed 5 months postoperatively demonstrated stifle arthrodesis with no detectable complications. The owner reported that aside from some difficulties in toileting, the cat had a good quality of life and was capable of performing the majority of daily activities. Stifle arthrodesis in a feline pelvic limb amputee appears to be a viable treatment option. After a period of rehabilitation and adaptation, the cat in the case report has been able to lead a near-normal lifestyle.

Relevance and novel information

To the authors' knowledge, this is the first report of the outcome and complications associated with stifle arthrodesis in a feline pelvic limb amputee. This is also the first report of stifle arthrodesis in a cat using the bilateral plating technique.

Measurement of Femoral Trochlear Morphology in Dogs Using Ultrasonography

OBJECTIVE

 The aim of this study was to examine a method for measuring femoral trochlear morphology in dogs using ultrasonography, and survey femoral trochlear morphology in skeletally normal dogs.

STUDY DESIGN

 To examine the validity of ultrasonography, three raters measured the sulcus angle (SA; the angle between the medial and lateral facets) five times in five skeletally normal dogs. Intra- and interrater reliabilities were then calculated. We also calculated the correlation coefficient between SAs measured using ultrasonography and computed tomography (CT) or magnetic resonance imaging (MRI). Then, we surveyed the femoral trochlear morphology in skeletally normal dogs using ultrasonography.

RESULTS

 The intra- and interrater reliability for SAs measured using ultrasonography was good, and the correlation coefficient between SAs measured using ultrasonography and CT, or MRI, was strong. In skeletally normal dogs, the SAs for osseous contours decreased until 6 months of age. However, the SAs for cartilaginous contours did not change during the growth period.

CONCLUSION

 The ultrasonographic measurement method is reliable for the evaluation of femoral trochlear morphology in dogs. The contour of the articular cartilage surface of the femoral trochlea is already determined early in life, and ossification of the articular cartilage of the femoral trochlea proceeds until 6 months of age. The results of this study will provide crucial information for the evaluation of femoral trochlear morphology in dogs.

Partial Parasagittal Patellectomy in Dogs: A Retrospective Case Series of 19 Dogs

OBJECTIVE

 The aim of this study was to describe partial parasagittal patellectomy for the surgical management of patellar luxation, including surgical technique, proposed indications, complications, and outcomes in a cohort of dogs.

STUDY DESIGN

 This is a single-center retrospective clinical case series.

METHODS

 Medical records (2019-2020) of dogs presenting for patellar luxation were reviewed. Clinical signs, luxation direction and grade, preoperative imaging and intraoperative findings, and complications were retrospectively retrieved. Owners were contacted via questionnaire for medium- and long-term follow-up.

RESULTS

 A total of 24 stifles in 19 dogs met the inclusion criteria. Intraoperative minor complications occurred in four stifles. A single minor complication occurred postoperatively with no major complications. Increased thickness and radiographic attenuation of the patellar ligament were noted in 14 stifles at radiographic reassessment. Re-luxation was not encountered, with long-term owner-assessed outcome as good to excellent in all cases.

CONCLUSION

 Partial parasagittal patellectomy, used in conjunction with block recession trochleoplasty and tibial tuberosity transposition, provided reliable resolution of patellar luxation in canine stifles with grade 2 or 3 luxation where width mismatch between the patella and the trochlea was noted intraoperatively. Long-term outcome appears to be good to excellent with a low rate of complication.

Evaluation of Surgical Technique and Clinical Results of a Procedure-Specific Fixation Method for Tibial Tuberosity Transposition in Dogs: 37 Cases

OBJECTIVE

 The aim of this study was to describe the use of a procedure-specific fixation method for tibial tuberosity transposition and report clinical outcome.

STUDY DESIGN

 This is a multi-institutional case series, evaluating 37 cases that were treated surgically for medial patellar luxation (MPL) and in which the tibial tuberosity transposition (TTT) was performed using the Rapid Luxation Plating System (RLPS). Surgical technique, implants, clinical outcome, and complications are reported.

RESULTS

 Surgery was successfully performed in dogs weighing 2.5 to 36.2 kg. Postoperative minor complications occurred in 13 cases (35%) and major complications occurred in 3 cases (8%). No implant-related complications or tibial tuberosity avulsions or fractures were seen. Outcome related to surgery was good or excellent in all cases.

CONCLUSION

 The RLPS for TTT provides a feasible technique in a large range of patients with MPL and lowers the occurrence of implant-related complications and tibial tuberosity avulsion or fracture.

Comparison of patellofemoral contact pressure after semi-cylindrical recession trochleoplasty and trochlear block recession in feline cadavers

Introduction

The purpose of this study was to compare the changes in the patellofemoral joint (PFJ) contact mechanisms of the normal state, trochlear hypoplasia model and after performing trochleoplasty on the hypoplasia model in feline cadavers.

Methods

Twenty normal pelvic limbs were acquired from the 10 feline cadavers. First, the PFJ contact mechanisms were measured in normal state, then trochlear hypoplasia models were created using customized trochlear ridge cutting guides. After measuring PFJ contact mechanisms in the trochlear hypoplasia models, they were divided into two groups and performed semi-cylindrical recession trochleoplasty (SCRT) and trochlear block recession (TBR) were performed, respectively. After that, the PFJ contact mechanisms were measured and the values of the 4 groups (normal state, trochlear hypoplasia, SCRT, TBR) were compared.

Results

The trochlear hypoplasia group showed increased contact pressure and decreased contact areas compared to the normal state group. In the groups that underwent tracheoplasty (SCRT and TBR), PFJ contact mechanisms were recovered similarly to that of the normal state group. The PFJ of the SCRP group was measured similar to that of the normal group than that of the TBR group.

Discussion

Tracheoplasty can be useful in restoring PFJ contact mechanisms and SCRT can be considered as a good alternative to the conventional methods of trochleoplasty.

Short-term outcomes for surgical correction of feline medial patellar luxations via semi-cylindrical recession trochleoplasty

Case series summary

Three cats (five stifles) were diagnosed with varying degrees of pelvic limb lameness secondary to medial patellar luxations (MPLs). Lameness did not resolve with medical management in any cat before referral for orthopedic evaluation. All cats underwent semi-cylindrical recession trochleoplasty (SCRT), medial fascial release and lateral imbrication for surgical repair of MPLs. All cats were re-evaluated at 3 and 8 weeks postoperatively and two cats were also evaluated at 16 weeks postoperatively. At the final rechecks, all cats had resolution of lameness of the operated limb(s) and no evidence of recurrence of patellar luxation.

Relevance and novel information

This case series demonstrated SCRT with soft tissue reconstruction as an acceptable option for surgical correction in three cats with MPLs. Short-term outcomes revealed minor complications and all patellae remained centralized.

Outcomes and complications of a modified tibial tuberosity transposition technique in the treatment of medial patellar luxation in dogs

OBJECTIVE

To report a modification of the tibial tuberosity transposition (m-TTT) technique used to treat medial patellar luxation (MPL) in dogs, and report its complications.

STUDY DESIGN

Retrospective case series.

SAMPLE POPULATION

Dogs (n = 235) undergoing MPL correction, using m-TTT (n = 300 stifles).

METHODS

Medical records and client surveys were reviewed to determine complications associated with this technique and they were compared with previously reported complications using similar techniques.

RESULTS

Short-term minor complications included low-grade reluxation (11 stifles, 3.6%), incisional seroma (nine stifles, 3%), pin-associated swelling (seven stifles, 2.3%), patellar desmitis (six stifles, 2%), superficial incisional infection (four stifles, 1.3%), pin migration (three stifles, 1%), tibial tuberosity (TT) fracture (two stifles, 0.6%), tibial tuberosity displacement and patella alta (one stifle, 0.3%), pin-associated discomfort (one stifle, 0.3%), trochlear block fracture (one stifle, 0.3%). Short-term major complications included pin migration (three stifles, 1%), incisional infection (two stifles, 0.6%), tibial tuberosity fracture (two stifles, 0.6%), and high grade reluxation (two stifles, 0.6%). Long-term follow-up examination data were available for 109/300 (36.3%) stifles. One minor complication and four major complications were documented. All long-term complications were due to pin migration. The overall major complication rate was 4.3% (13/300 stifles), with a minor complication rate of 15% (46/300 stifles). The owner survey indicated a 100% satisfaction rate.

CONCLUSION

The m-TTT technique yielded acceptable complication rates, with high owner satisfaction.

CLINICAL SIGNIFICANCE

The m-TTT should be considered as an alternative technique for treating dogs with MPL requiring a tibial tuberosity transposition.

The value of routine radiographic follow up in the postoperative management of canine medial patellar luxation

OBJECTIVE

To determine the influence of radiographic examination on the recommendations made at the time of planned re-evaluation of dogs after medial patellar luxation (MPL) surgery.

STUDY DESIGN

Retrospective multi-institutional case series.

ANIMALS

Client-owned dogs (N = 825) that underwent MPL surgery.

METHODS

Records of 10 referral institutions were searched for dogs that had been treated surgically for unilateral MPL and underwent a planned follow-up visit, including radiographs. The frequency of, and reasons for, changes in further recovery recommendations were investigated.

RESULTS

Follow up was performed at a median of 6 (range, 4-20) weeks postoperatively. Isolated radiographic abnormalities were identified in 3.3% (27/825) of dogs following MPL surgery and led to a change in recommendations in 3% (13/432) of dogs that were presented without owner or clinician concerns. Lameness, administration of analgesia at follow up, and history of unplanned visits prior to routine re-examination were associated with a change in postoperative plan (P < .001). In the absence of owner and clinician concerns, the odds of having a change in convalescence plans were not different, whether or not isolated radiographic abnormalities were present (P = .641).

CONCLUSION

Routine radiographs at follow up did not influence postoperative management of most dogs after MPL surgery in the absence of abnormalities on clinical history or orthopedic examination.

CLINICAL SIGNIFICANCE

Dogs that were presented for routine follow up after unilateral MPL surgery without owner concerns, lameness, analgesic treatment or a history of unplanned visits, and for which examination by a surgical specialist was unremarkable, were unlikely to benefit from radiographs.

Influence of Kirschner-Wire Insertion Angle on Construct Biomechanics following Tibial Tuberosity Osteotomy Fixation in Dogs

OBJECTIVES

 The aim of this study was to evaluate the effect of Kirschner wire insertion angle on the biomechanical characteristics following tibial tuberosity osteotomy fixation in dogs.

STUDY DESIGN

 Twelve pairs of cadaveric tibia were harvested and randomly assigned to two treatment groups. Kirschner wires were placed either transversely (0 degrees) or placed caudodistally (30 degrees) with respect to the tibial tuberosity osteotomy. Each limb acted as its own respective control. Radiographic analysis allowed for the calculation of Kirschner wire insertion angle variance. Constructs were tested to monotonic failure while evaluating yield, peak, and failure forces, construct stiffness, and failure mode.

RESULTS

 Kirschner wire insertion angles were 1.1 ± 2.2 degrees and 30.5 ± 2.3 degrees, respectively, for 0-degree and 30-degree groups (p <0.0001). Yield (p = 0.0095), peak (p <0.024) and failure loads (p <0.030) were all significantly greater for Kirschner wires inserted at an angle of 0 degrees compared with 30 degrees. Construct stiffness did not differ regardless of insertion angle (p = 0.068). Failure mode did not differ (p = 0.87) with tibial tuberosity avulsion and Kirschner wire pull-out seen in the majority of constructs (67%).

CONCLUSION

 Kirschner wires placed transversely (0 degrees) for tibial tuberosity osteotomy fixation were biomechanically superior, increasing yield, peak, and failure forces by 1.6 times, 1.3 times, and 1.4 times, respectively, to those placed in a caudodistal (30 degrees) orientation. Kirschner wire insertion angle is an important consideration following tibial tuberosity osteotomy in dogs, with Kirschner wires placed at 0 degrees conferring increased resistance of the repair to construct deformation.

Preoperative and postoperative stance analysis in dogs with patellar luxation confirms lameness improvement after surgery

OBJECTIVE

To document and compare preoperative and postoperative stance analysis measurements in animals with naturally occurring patellar luxation.

ANIMALS

131 client-owned dogs surgically treated for naturally occurring unilateral or bilateral patella luxation between March 30, 2015, and February 12, 2020.

PROCEDURES

Weight bearing as a percent body weight on each limb was recorded with the use of a platform device for analyzing stance (PetSafe Stance Analyzer; LiteCure LLC, Companion Animal Health) preoperatively and postoperatively for all dogs. Signalment, limb affected, lameness grade, luxation direction, luxation grade, and surgical procedure were collected from patient records and assessed for the effects of these variables on weight bearing preoperatively or at the first or second postoperative recheck examination.

RESULTS

There were 61 males and 70 females, with a mean age and body weight of 4.62 years and 13.01 kg, included in the study. As age increased, body weight decreased in these dogs (P = .025). There was a statistically significant improvement in lameness after surgery (P = .008) at the second postoperative recheck examination. Lameness significantly decreased as postoperative time increased (P < .001, r = 0.503). As age increased, lameness at the initial visit decreased compared to younger dogs but not significantly (P = .062). There was no significant effect of preoperative luxation grade, luxation direction, surgical procedure, or sex when comparing initial lameness or lameness at recheck examination.

CLINICAL RELEVANCE

Surgical correction of patella luxation improves lameness as measured by postoperative stance analysis. Preoperative luxation grade or direction, surgical procedure performed, and sex of the animal did not significantly affect outcome in this group of dogs.

The effect of grip location on Kirschner wire bend characteristics: An in vitro study

OBJECTIVE

To determine the effect of Kirschner wire (K-wire) grip location on bend angle, bend radius, and torque when performing a Z-bend technique.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Ten samples at each of five grip locations for each of three K-wire diameters.

METHODS

K-wires of three diameters (0.9, 1.1, 1.6 mm) were drilled into PVC pipe, and a Jacob's chuck was used to bend the wires at five periodic grip locations (distance from the bone model). Torque, bend angle, and bend radius were determined for each sample. Outcome variables were statistically analyzed by grip location to determine significant relationships.

RESULTS

A grip location of 2.0 cm in the 0.9 mm K-wire group minimized bend angle (mean ± SD: 75.92° ± 0.81) and bend radius (2.89 mm ± 0.08). A grip location of 3.0 cm in the 1.1 mm K-wire group minimized bend angle (72.88° ± 0.98) and bend radius (2.47 mm ± 0.20). A grip location of 3.0 cm minimized bend angle (74.38° ± 1.93) and bend radius (2.71 mm ± 0.27) in the 1.6 mm K-wire group. Torque at these grip locations for the 0.9, 1.1, and 1.6 mm K-wires was 6.50 N-m ± 0.0, 11.00 N-m ± 0.0, and 19.05 N-m ± 0.16, respectively.

CONCLUSION

Bend angle and bend radius can be minimized by bending K-wires at specific grip locations, though torque is not minimized at these locations. Clinical significance These findings provide an evidence-based recommendation of where surgeons should grip K-wires when bending them.

Good clinical outcomes achieved in young dogs with tibial tuberosity avulsion fracture repairs when implants were left in situ past skeletal maturity

OBJECTIVE

To evaluate outcomes of tibial tuberosity avulsion fractures (TTAF) in dogs with implants left in situ past skeletal maturity and to compare clinical outcomes with published outcomes in dogs whose implants were removed 4 to 6 weeks postoperatively.

ANIMALS

47 client-owned dogs.

PROCEDURES

In this retrospective study, 47 dogs had surgery to correct a TTAF before 10 months of age and had the implants left in situ past skeletal maturity. Of these, 42 were followed for a median of 36 months postoperatively. Short- and long-term complications were recorded and compared with historically published data in which the implants were removed within 6 weeks of surgery.

RESULTS

14% (6/42) of our population experienced minor long-term complications (stiffness and lameness), 6% (3/47) experienced major short-term complications (repair failure), and 14% (6/24) experienced major long-term complications (implant removal). There was no difference in long-term outcomes when compared with results of historical reports in which implants were removed 4 to 6 weeks postoperatively. Client satisfaction was high, with 93% (38/41) grading outcomes as excellent and 95% (39/41) stating they would have surgery performed again in retrospect.

CLINICAL RELEVANCE

Immature dogs with surgically repaired TTAFs have favorable long-term outcomes when the implants were left in situ past skeletal maturity. Dogs with TTAF repairs may not need implant removal unless it becomes clinically necessary. Avoiding a second procedure will decrease patient morbidity, recovery time, and cost.

Computed Tomographic Measurements of the Sulcus Angle of the Femoral Trochlea in Small-Breed Dogs with and without Medial Patellar Luxation

Trochleoplasty is often performed in dogs with medial patellar luxation (MPL); however, the current guidelines on when to perform a trochleoplasty in dogs are vague. The sulcus angle (SA) is used to assess the femoral trochlear morphology in humans. The aim of this study is to describe a method to measure the SA and other parameters of trochlea morphology in dogs using computed tomography. First, we searched for a suitable measuring location for the SA. Transverse images of the femurs were obtained as perpendicular planes to the tangent of the femoral trochlea which was 0 to 60 degrees (every 5 degrees) to the anatomical axis of the femur. The deepest point of the femoral trochlea was found in the transverse images perpendicular to the tangent of the femoral trochlea which was at 15 degrees to the anatomical axis of the femur. The SA and the other parameters of femoral trochlea morphology were measured at the deepest point of the femoral trochlea. The SA of the stifle joints with grade 3 and 4 MPL was significantly higher than the SA of stifle joints not affected by MPL. There was no significant difference in the SA between dogs affected by grade 1 and 2 MPL and dogs not affected by MPL. Further studies are needed to establish whether the SA can be used as selection criteria for trochleoplasty.

Tibial Tuberosity Transposition Fixation with a Locking Plate during Medial Patellar Luxation Surgery: An Ex Vivo Mechanical Study

OBJECTIVES

 The purpose of this study was to compare the load at failure, stiffness and mode of failure between three types of tibial tuberosity transposition fixation techniques: (a) pin and figure-8 tension band wire (Pin-TBW), (b) locking plate with pin and a tension band wire (Plate-Pin-TBW) and (c) locking plate with a pin (Plate-Pin).

METHODS

 Six pairs of raccoon dog cadaveric tibiae were tested in Phase I Pin-TBW versus Plate-Pin-TBW and seven pairs in Phase II Plate-Pin-TBW versus Plate-Pin. One limb of each pair was randomly assigned to one of two groups for each phase. A tensile force was applied to the patellar ligament until construct failure.

RESULTS

 Pin-TBW (342N ± 54.7N) failed at a lower load than Plate-Pin-TBW (469N ± 77.3N), p = 0.00748, with all Pin-TBW failing by fracture and the majority of Plate-Pin-TBW failing by rupture of patellar ligament. Pin-TBW group Phase I, normalized with Plate-Pin-TBW Phase I, failed at a lower load than Plate-Pin group Phase II, normalized with Plate-Pin-TBW Phase II, p = 0.00467. There was no significant difference in mean load at failure, stiffness or mode at failure between the groups in the Phase II study.

CLINICAL SIGNIFICANCE

 Although ex vivo mechanical testing does not replicate the postoperative live dog or cat, these results demonstrate lower construct strength of the Pin-TBW construct compared with the Plate-Pin construct in the raccoon dog cadaver model.

Proximodistal and caudocranial position of the insertion of the patellar ligament on the tibial tuberosity and patellar ligament length of normal stifles and stifles with grade II medial patellar luxation in small-breed dogs

OBJECTIVE

To assess the role of the proximodistal and caudocranial relative position of the patellar ligament insertion on the tibia and patellar ligament length-to-patellar length ratio (PLL:PL) in small-breed dogs with and without grade II medial patellar luxation (MPL).

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Dogs weighing ≤15 kg, including 43 stifles with MPL and 34 control stifles.

METHODS

The proximodistal and caudocranial relative position of the patellar ligament insertion was determined as a ratio using the vertical (VTT) and horizontal distance (HTT) between the tibial tuberosity insertion and the tibial plateau divided by the tibial plateau length (TPL). In addition, PLL:PL and tibial plateau angle (TPA) were determined.

RESULTS

The VTT:TPL ratio was lower in affected stifles (95% CI: 0.86-0.94) than in the control group (0.93-1.01; p = .01). No other difference was identified between affected and normal stifles.

CONCLUSION

The only difference identified in this study consisted of a more proximal position of the patellar ligament insertion in the stifles of small-breed dogs with grade II MPL.

CLINICAL SIGNIFICANCE

The more proximal position of the patellar ligament insertion will result in a more proximal position of the patella in the trochlear groove and may contribute to the development of MPL. Potentially, this will also affect the risk of recurrence of MPL after surgical treatment.

Biomechanical Comparison of Three Stabilization Methods for Tibial Tuberosity Fractures in Dogs: A Cadaveric Study

OBJECTIVE

 The aim of this study was to compare the biomechanical properties of a hybrid external skeletal fixator (HESF) construct to the placement of paired interfragmentary Kirschner wires alone, and pin and tension band wire (PTBW) fixation for the stabilization of simulated tibial tuberosity fractures in dogs.

STUDY DESIGN

 Tibias were harvested from 12 skeletally mature dog cadavers weighing 20 to 30 kg. An osteotomy was made through the base of the tibial tuberosity, which was subsequently repaired with either paired Kirschner wires, PTBW fixation or a HESF. A tensile load was applied to the tibial tuberosity until failure occurred. Mode of failure was described and biomechanical parameters obtained were compared between fixation groups.

RESULTS

 The PTBW fixation and HESF construct afforded greater stiffness and load at 3 mm of axial displacement compared with fixation with Kirschner wires alone. There was no significant difference in stiffness and load at 3 mm displacement between PTBW and HESF fixation. Failure occurred by bending and pullout of the Kirschner wires for all fixation groups, preceded by untwisting of the knot in PTBW specimens.

CONCLUSION

 The HESF may provide a favourable alternative to PTBW fixation for tibial tuberosity avulsion fracture stabilization in dogs with substantial remaining growth potential.

Biomechanical analysis of canine medial patellar luxation with femoral varus deformity using a computer model

Background

Femoral varus deformities complicating the realignment of the quadriceps muscles are frequently associated with medial patellar luxation (MPL) in dogs. Therefore, distal femoral osteotomy (DFO) is recommended in dogs affected with severe MPL and a distal femoral varus deformity. The presence of an anatomic lateral distal femoral angle (aLDFA) of ≥ 102° has been anecdotally recommended as an indication for performing corrective DFO in large-breed dogs. However, the effect of a femoral varus deformity on MPL has not been scientifically evaluated. We aimed to evaluate the influence of a femoral varus deformity on MPL using a finite element method based computer model.

Three-dimensionally reconstructed computed tomographic images of a normal femur from a Beagle dog were deformed using meshing software to create distal varus deformities. A total of thirteen aLDFAs, including 95°, 98° and 100°–110°, were simulated. The patellar positions and reaction force between the patella and trochlear grooves were calculated for all finite element models under constant rectus femoris muscle activation.

Results

The patella was displaced medially from the trochlear groove at an aLDFA of ≥103°. With an aLDFA of 103° to 110°, the reaction force was equal to zero and then decreased to negative values during the simulation, while other models with aLDFAs of 95°, 98°, and 100°-102° had positive reaction force values. The patella began to luxate at 24.90 seconds (sec) with an aLDFA of 103°, 19.80 sec with an aLDFA of 104°, 21.40 sec with an aLDFA of 105°, 20.10 sec with an aLDFA of 106°, 18.60 sec with an aLDFA of 107°, 15.30 sec with an aLDFA of 108°, 16.60 sec with an aLDFA of 109°, and 11.90 sec with an aLDFA of 110°.

Conclusion

Severe distal femoral varus with an aLDFA of ≥103° caused MPL when other anatomical factors were controlled. Thissimplified computer model provides complementary information to anecdotal cutoffs for DFO, hence it should be applied to clinical patients with caution.

Computed Tomographic Measurement of Trochlear Depth in Three Breeds of Brachycephalic Dog

OBJECTIVE

 The aim of this study was to determine the trochlear sulcus depth of three common brachycephalic breeds at risk of medial patellar luxation.

STUDY DESIGN

 Retrospective blinded clinical study using a previously validated ratio (T/P) of maximal trochlear sulcus depth (T) and maximal patellar craniocaudal thickness (P) measured on computed tomography, to assess trochlear sulcus depth in Pugs, French Bulldogs and English Bulldogs without clinical patellar luxation. The effect of breed on T/P was assessed using one-way linear regression models.

RESULTS

 The mean T/P was affected by breed (p < 0.001). There was significant difference between Pugs (0.45) and French Bulldogs (0.38) and between Pugs and English Bulldogs (0.4). There was no significant difference between Pugs and previously published data for non-brachycephalic and mixed breed dogs (0.46) (p = 0.39). Mean T/P was significantly reduced in the brachycephalic dog breeds combined compared with the previously published data (p < 0.001).

CONCLUSION

 The trochlear sulcus varies by breed and was more shallow in French and English Bulldogs than Pugs, hence a shallow sulcus may be a breed-driven characteristic. The three breeds assessed are at risk of patellar luxation but sulcus depth did not directly correlate with previously published risk factors-the contribution of sulcus depth to the aetiopathogenesis of patellar luxation remains unclear. Trochlear recession to achieve patellar coverage of 50% may be excessive considering maximal breed normal depth.

Comparison of Semi-Cylindrical Recession Trochleoplasty and Trochlear Block Recession for the Treatment of Canine Medial Patellar Luxation: A Pilot Study

OBJECTIVE

 The aim of this study was to describe an alternative method for trochleoplasty, semi-cylindrical recession trochleoplasty (SCRT), and compare it to trochlear block recession (TBR) in regard to recessed trochlear depth, patellar depth, patellar articular contact with the trochlea, recessed trochlear surface area, procedure time, complications and functional outcome.

STUDY DESIGN

 Ten dogs with bilateral grade II-III medial patellar luxations underwent bilateral simultaneous correction surgery including tibial tuberosity transposition, lateral imbrication and trochleoplasty with one stifle each undergoing TBR and SCRT. Patients received pre-and postoperative stifle computed tomography scans and pre- and 8-week postoperative pressure platform analysis and physical examinations. Recessed trochlear depth, patellar depth, trochlear surface area, patellar articular contact, procedure time, complications and functional outcomes as measured by gait analysis were compared between the two techniques.

RESULTS

 There was no significant difference in measured outcome variables between techniques at any time point. At the time of the 8-week reassessment, no patella had reluxated.

CONCLUSION

 Short-term follow-up shows similar functional outcomes between both techniques regarding rate of reluxation and limb function. The SCRT was subjectively easier to perform than TBR, particularly in small patients. The SCRT is an acceptable method of trochleoplasty for the treatment of medial patellar luxation in dogs and further studies evaluating long-term outcomes are justified.

Tibial Apophyseal Percutaneous Pinning in Skeletally Immature Dogs: 25 Cases (2016-2019)

OBJECTIVE

 The aim of this study was to report the clinical experience with fluoroscopically guided tibial apophyseal percutaneous pinning (TAPP) for tibial tuberosity avulsion fractures (TTAF).

STUDY DESIGN

 This is a retrospective case series.

MATERIALS AND METHODS

 Medical records of skeletally immature dogs (n = 25) were reviewed. The association of pin design [smooth (SP); negatively threaded (NTP)], pin insertion angles, TTAF-type, age and breed with various outcome variables was statistically evaluated. Long-term follow-up was assessed via direct examination, radiographs, questionnaires and videos.

RESULTS

 Mean age, weight and surgery times were 6.2 months, 9.6 kg and 21 minutes respectively. No major complications occurred among the 19 SP and 6 NTP; no pin broke. Seromas and patellar desmitis rates were higher with SP (11/19; 16/19) versus NTP (0/6; 2/6) (p = 0.02; 0.03). The median horizontal pin cross angles for cases without and with desmitis were 40 and 26 degrees respectively (p = 0.047). Explantation was needed in 5/19 SP and 0/6 NTP cases. The mean tibial plateau angle (TPA) changed significantly between initial (25.6 degrees) and follow-up (18.8 degrees) radiographs (p = 0.0002). Long-term outcome, obtained at a mean of 19.9 months, was excellent in all cases.

CONCLUSION

 Tibial apophyseal percutaneous pinning can be considered to treat TTAF. Divergent pin placement and using NTP might reduce complications. Tibial plateau angle should be monitored until skeletal maturity has been reached. Long-term outcome post TAPP can be expected to be excellent.

Radiographic evaluation of patellar tendon length following corrective surgical procedures for medial patellar luxation in dogs

Objective

To quantify changes in the patellar tendon length following surgical correction of medial patellar luxation in dogs and evaluate potential risk factors associated with patellar tendon elongation.

Study design

Retrospective case series (n = 50).

Methods

Dogs that underwent surgery for medial patellar luxation correction and had 2–3 months follow up were included. Digital radiographs were utilized to quantify the patellar tendon length to patellar length ratio at various follow-up points. Odds ratio comparisons between potential risk factors associated with changes in patellar tendon length were performed.

Results

Post-operative patellar tendon lengthening of ≥ 5% was observed in 20% of stifles and post-operative patellar tendon shortening of ≥ 5% was observed in 22% of stifles at the 2–3 month follow up period. The risk factors including age, body weight, trochleoplasty and grade of medial patellar luxation were not significantly associated with risk of patellar tendon elongation. Patellar tendon lengthening was not associated with recurrence of luxation.

Conclusion

Patellar tendon lengthening and shortening can be observed in dogs following common medial patellar luxation corrective procedures in the short term follow up period. Patellar tendon lengthening does not appear to be associated with age, weight, trochleoplasty, grade of luxation, or risk of luxation recurrence.

Effect of Limb Position on Measurements of the Quadriceps Muscle Length/Femoral Length Ratio in Normal Beagle Dogs

OBJECTIVES

 Dogs with patella alta reportedly have a shorter extensor mechanism than normal dogs. The present study aimed to measure the length of the extensor mechanism and to assess the effect of limb position on the quadriceps muscle length (QML)/femoral bone length (FL) ratio.

STUDY DESIGN

 Three-dimensional computed tomography images were taken of 12 Beagle dogs. Each dog underwent computed tomographic imaging 24 times with different limb positions. The QML/FL was measured on each image, along with the hip flexion-extension, hip abduction-adduction and stifle flexion-extension angles. Multiple regression analysis was used to determine the effect of these angles on the QML/FL.

RESULTS

 The QML/FL was increased with the hip extended (standardized partial regression coefficient 0.855 with linear plotting, 0.829 with log plotting) and with the stifle flexed (standardized partial regression coefficient 0.814 with linear plotting, 0.800 with log plotting). The partial regression coefficient of the hip abduction-adduction angle was small, indicating a small impact on the QML/FL. The 95% confidence range of the QML/FL with the hip extended and stifle flexed was 0.87 to 1.00 (mean ± standard deviation: 0.93 ± 0.03).

CONCLUSION

 The QML/FL was more influenced by joint angles when the hip was flexed or the stifle was extended. Hence, these positions should be avoided when evaluating the QML/FL so that the QML is less altered by slight positioning disparities.

The natural history of canine occult Grade II medial patellar luxation: an observational study

OBJECTIVES

To determine the risk of lameness and the rate of subsequent medial patellar luxation surgery in dogs that present with occult Grade II medial patellar luxation.

MATERIALS AND METHODS

Retrospective owner survey and review of clinical records of adult dogs diagnosed with Grade II medial patellar luxation that were initially asymptomatic and managed non-surgically that had a minimum of 4-year follow-up. Clinical notes and owner questionnaires identified dogs that subsequently developed lameness and required surgery on the previously asymptomatic stifle.

RESULTS

Thirty-eight dogs were included with an average follow-up of 51 months. Seventeen dogs re-presented for unscheduled contralateral medial patellar luxation surgery at an average of 15 months after initial presentation. A further two dogs had chronic contralateral limb lameness after an average of 33 months after initial surgery and may have been potential surgical candidates.

CLINICAL SIGNIFICANCE

Fifty percent of adult dogs presenting with occult Grade II medial patellar luxation subsequently developed chronic lameness or required surgery.

Accuracy of patient-specific three-dimensional-printed osteotomy and reduction guides for distal femoral osteotomy in dogs with medial patella luxation

OBJECTIVE

To compare precorrectional and postcorrectional femoral alignment following distal femoral osteotomy using patient-specific 3-dimensional (3D)-printed osteotomy and reduction guides in vivo and ex vivo.

STUDY DESIGN

Prospective study.

SAMPLE POPULATION

Ten client-owned dogs and matching 3D-printed plastic bone models.

METHODS

Distal femoral osteotomy was performed via a standard approach using osteotomy and reduction guides developed with computer-aided design software prior to 3D-printing. Femoral osteotomy and reduction was also performed on 3D-printed models of each femur with identical reprinted guides. Femoral varus angle (FVA) and femoral torsion angle (FTA) were measured on postoperative computed tomographic images by 3 observers.

RESULTS

In vivo, the mean difference between target and achieved postoperative was 2.29° (±2.29°, P = .0076) for the FVA, and 1.67° (±2.08°, P = .300) for the FTA. Ex vivo, the mean difference between target and achieved postoperative was 0.29° (±1.50°, P = .813) for the FVA, and -2.33° (±3.21°, P = .336) for the FTA. Intraobserver intraclass correlation coefficients (ICC; 0.736-0.998) and interobserver ICC (0.829 to 0.996) were consistent with an excellent agreement.

CONCLUSION

Use of 3D-printed osteotomy and reduction guides allowed accurate correction of FTA in vivo and both FVA and FTA ex vivo.

CLINICAL SIGNIFICANCE

Use of 3D-printed osteotomy and reduction guides may improve the accuracy of correction of femoral alignment but warrant further evaluation of surgical time, perioperative complications, and patient outcomes compared with conventional techniques.

Comparison of short-term complications between unilateral and single-session bilateral surgery for medial patellar luxation in small/medium breed dogs

OBJECTIVES

To compare the short-term complications of unilateral versus single-session bilateral medial patellar luxation surgery in small dogs.

MATERIALS AND METHODS

The medical records of dogs weighing less than 13∙6 kg that underwent medial patellar luxation surgery were reviewed. Dogs were included in one of two groups based on the type of surgery performed (unilateral or single-session bilateral). Postoperative patellar luxation grade and complications were compared between the groups.

RESULTS

Two hundred and fifty-one dogs were included. In the bilateral treatment group, there was less improvement in patellar luxation grade and postoperative medial patellar luxation grade was higher. The frequency of major complications was higher in the bilateral group (23%) compared with the unilateral group (12%).

CLINICAL SIGNIFICANCE

Single-session bilateral medial patellar luxation surgery was associated with a higher complication rate compared to unilateral surgery in this non-randomised observational study. Staged rather than single-session bilateral surgery should be considered in dogs with bilateral medial patellar luxation to improve clinical outcome and reduce the chance of major complications.

Patellar luxation in dogs

Patellar luxation is a common orthopedic problem in dogs. Medial luxation is more common than lateral luxation and is usually diagnosed in dogs of small breed. Diagnosis is based on clinical evidence of patellar instability; however, diagnostic imaging is required to assess the amount of skeletal deformity and then the most appropriate method of treatment. Surgical options include both soft tissue and osseous techniques, however, in most of the cases, a combination of more procedures is used to achieve the correction of the luxation. Complication rate is generally low and the most common complications include reluxation and implant-associated complications. Prognosis is generally favorable, with most of the dogs returning to normal limb function. This article describes patellar luxation features in dogs, including clinical presentation, diagnosis, and treatment options available.

Distal tibial tuberosity translation using TTA implants for the treatment of patella alta in large breed dogs

Introduction: Medial patellar luxation frequently occurs in dogs resulting in lameness with increasing incidence in large breed dogs. Patella alta has been defined as a patellar ligament length to patellar length ratio that is greater than two and may predispose to patellar luxation.

Objective: To describe the surgical technique for stabilization of the distal translation of the tibial tuberosity using tibial tuberosity advancement plates and the clinical outcomes with follow-up for clinical cases of dogs.

Methods: Dogs that were presented with the complaint of patellar luxation and that were concurrently diagnosed with patella alta and were greater than 20 kg in body weight underwent surgery using a tibial tuberosity advancement plate to stabilize the osteotomy. Radiographic assessment of A:PL distance (the ratio of the proximal aspect of the patella to the femoral condyle [A] to the patellar length [PL]), L:P ratio (ratio of the length of the patellar ligament to the diagonal length of the patella), and owner assessment were obtained.

Results: Eleven stifles in nine dogs underwent surgical correction with a mean preoperative L:P ratio of 2.47. There were no complications and the lameness resolved clinically. The mean A:PL ratios preoperatively (2.6 ± 0.22) and postoperatively (2.1 ± 0.25) were significantly different (p = 0.0003). All owners were satisfied with the outcome and all dogs had a resolution of lameness with no recurrence of patellar luxation.

Clinical significance: Stabilization of distal translation of the tibial tuberosity using tibial tuberosity advancement implants to correct patella alta in large breed dogs was feasible and resulted in good clinical outcome.

Surgical stabilization of concomitant canine medial patellar luxation and cranial cruciate ligament disease

Objectives: To compare complication rates and outcomes between cases of concomitant cranial cruciate ligament (CrCL) disease and medial patellar luxation (MPL) treated using extracapsular stabilization and tibial tuberosity transposition (ECS+TTT) and tibial tuberosity transposition and advancement (TTTA).

Methods: In a multicentre retrospective study, records from four referral hospitals were reviewed for dogs with concomitant CrCL pathology and MPL treated using ECS+TTT or TTTA. Data retrieved included signalment, partial/complete CrCL tear, MPL grade, treatment performed, occurrence of postoperative complications, and postoperative outcome grade. Associations between surgical procedure and risk of complication and surgical procedure and outcome were investigated using univariable logistic regression and proportional odds logistic regression respectively. Multiple logistic regression was used to explore confounding factors.

Results: A total of 72 stifles were evaluated in 66 dogs; 32 stifles were stabilized using ECS+TTT and 40 using TTTA. Overall complications were 2.7 times more frequent in the ECS+TTT group and major complications occurred only in this group. The TTTA group was less likely to suffer complications (17.5%) compared to the ECS+TTT group (46.9%) (p = 0.009) and TTTA cases had lower odds of a poorer clinical outcome (p = 0.047).

Clinical significance: Stifles stabilized using ECS+TTT are more likely to suffer from postoperative complications and a poorer clinical outcome when compared to TTTA.

Supplementary Material to this article is available online at https://doi.org/10.3415/VCOT-16-10-0148

Prevalence, treatment and outcome of patellar luxation in dogs in Italy

Objective: To determine the prevalence of patellar luxation in dogs in Italy and its relation to signalment, the frequency and the type of postoperative complications and the outcome of treatment, and to compare the findings with those of other studies.

Materials and methods: The medical records from four referral clinics were searched for dogs with orthopaedic disorders referred from 2009 to 2014. From these data, the records of dogs with patellar luxation were identified, and the signalment, age and body weight, grade, side and direction of patellar luxation, treatment, postoperative complications, and outcome were retrieved. Univariate and multivariate statistical analyses were used to evaluate the data.

Results: Of 8,694 canine orthopaedic cases, fractures not included, patellar luxation was diagnosed in 559 dogs (801 stifles). Mixed breed dogs were most commonly affected (18%), 85% of the luxations were medial, and 52% of the dogs were female. Of the 559 dogs examined, 400 (574 stifles) met the inclusion criteria for treatment evaluation. Minor complications occurred in five percent of the dogs, and major complications in 16%, including recurrence of patellar luxation in seven percent of the dogs. The outcome was good in 88% of stifles, fair in two percent, and poor in 10%.

Clinical significance: Although patellar luxation was more common in small breed dogs, it also was diagnosed in a significant number of large breed dogs, which included medial patellar luxation in 73% and lateral patellar luxation in 27% of stifles. Body weight and grade of luxation were the only variables statistically correlated with surgical complications.

ORCID iD AV: http://orcid.org/0000-0003-2837-7822

Percutaneous tibial physeal fracture repair in small animals: technique and 17 cases

OBJECTIVES

To retrospectively describe cases treated via percutaneous tibial physeal fracture repair (PTPFR), using intra-operative fluoroscopy (IFL) or digital radiography (DR). To describe a technique ("spiking"), used to treat tibial tuberosity avulsion fractures.

METHODS

Clinical data of 14 dogs and three cats were included. The "spiking" technique was described.

RESULTS

Intra-operative fluoroscopy (n = 11) and DR (n = 6) were successfully used in 11 tibial tuberosity avulsion fractures, one combined proximal physeal and tibial tuberosity avulsion fracture, and five distal tibial/fibular physeal fractures. Surgery times ranged from eight to 54 minutes. The "spiking" technique was successfully applied in six tibial tuberosity avulsion fracture cases. Return to function was at a mean (± standard deviation) of 1.9 (± 1.6) weeks. Long-term (>12 months; n = 17) follow-up was available at a mean of 40.6 (± 13.4) months. Major complications consisted of skin irritation from a pin (distal tibia / fibula physeal fracture case; 8 weeks post-PTPFR), and a bilateral grade II medial patella luxation (tibial tuberosity avulsion fracture case; 1.5 years post-PTPFR). One case developed a mild tibial tuberosity avulsion fracture re-avulsion. All conditions in these three cases were not of clinical concern at follow-up and final outcome was graded as good in these and excellent in the other 14 cases.

CLINICAL SIGNIFICANCE

Percutaneous tibial physeal fracture repair can be considered as a technique to treat tibial physeal fractures. The "spiking" technique was successfully applied in six dogs. A larger, prospective case series is indicated to provide additional clinical information.

Impact of femoral varus on complications and outcome associated with corrective surgery for medial patellar luxation

OBJECTIVES

To evaluate the association of femoral varus with postoperative complications and outcome following standard corrective surgery for medial patellar luxation (MPL) without distal femoral osteotomy (DFO) in dogs.

METHODS

In a retrospective study spanning a 12 year period, 87 stifles with MPL that were treated by standard surgical techniques were included. Inclination angle (ICA), femoral varus angle (FVA), anatomical lateral distal femoral angle (aLDFA), and mechanical lateral distal femoral angle (mLDFA) were measured. Postoperative complications were noted and outcome evaluated. Associations between potential risk factors and both complication rate and outcome were assessed.

RESULTS

Postoperative complications occurred in 19 stifles, five of which were major. There was no evidence of an association between FVA (p = 0.41) or aLDFA (p = 0.38) and any complication. There was also no evidence of an association between FVA (p = 0.31) or aLDFA (p = 0.38) and any major complication. Dogs with a larger aLDFA had increased odds of a poorer outcome (p = 0.01) as did dogs that suffered a major complication (p = 0.0001).

CLINICAL SIGNIFICANCE

Based on radiographic measurements, there is no evidence of an association between FVA and the incidence of postoperative complications following standard MPL correction. Traditional surgical techniques appear to be appropriate for most cases of MPL and further work is required to better define selection criteria for including DFO in the treatment of these cases.

Lateral patellar luxation in nine small breed dogs

The objective of this paper was to describe the clinical features, the management and the outcome of nine small breed dogs affected with lateral patella luxation referred during the period between January 2010 and December 2014. Patellar luxations were classified according to: breed, age, sex, weight, and grade of patellar luxation, as well as if unilateral or bilateral, and concurrent cranial cruciate ligament lesion. In affected dogs, surgical correction consisted in the combination of tibial tuberosity transposition and soft tissue procedure. Adjunctive condroplasty or trochleoplasty was performed as needing. The outcome was found positive after surgical management with low complication rate and complications have been easily managed with high success rate.

Proximo-distal patellar position in three small dog breeds with medial patellar luxation

INTRODUCTION

Medial patellar luxation is thought to be associated with a high proximal position of the patella in the trochlear groove.

OBJECTIVE

To determine whether the ratio of patellar ligament length and patellar length (L:P) is influenced by the stifle angle (75°, 96°, 113°, 130°, and 148°) in small dog breeds and to compare the L:P ratio in dogs of three small dog breeds with and without medial patellar luxation.

METHODS

A mediolateral radiograph of the stifle joint was used to measure the L:P ratio in the stifle joints of dogs of three small breeds with and without medial patellar luxation. The L:P ratio was evaluated at five stifle angles (75°, 96°, 113°, 130°, and 148°) in 14 cadavers (26 stifle joints) of small dog breeds in order to identify the best stifle angle to measure the L:P ratio. Then the mean ± SD L:P ratio was calculated for normal stifles and stifles with medial patellar luxation grades 1, 2, and 3 in 194 Pomeranians, 74 Chihuahuas, and 41 Toy or Standard Poodles.

RESULTS

The L:P ratio was the same for all five stifle angles in the cadavers (p = 0.195). It was also not significantly different in the three breeds (p = 0.135), in normal and medial patellar luxation-affected stifles overall (p = 0.354), and in normal and medial patellar luxation-affected joints within each breed (p = 0.19).

CLINICAL SIGNIFICANCE

We conclude that a proximo-distal patellar position is not associated with medial patellar luxation in Pomeranians, Chihuahuas, and Toy or Standard Poodles. Thus a longer patellar ligament length does not play a role in the pathophysiology of medial patellar luxation in these small dog breeds.