Implant removal rate after partial carpal arthrodesis in dogs: A retrospective analysis of 22 cases.

Introduction: The purpose of this study is to determine the rate of implant removal after partial carpal arthrodesis and to investigate factors associated with implant removal. Methods: Case records of 22 dogs that underwent partial carpal arthrodesis at two private veterinary referral hospitals were reviewed. Details retrieved were body weight at time of surgery, sex, neuter status, breed, age, cause of carpal hyperextension injury, joint(s) involved in carpal hyperextension injury, laterality, type of implant, administration of post-operative antibiotics, post-operative outcome and indication for implant removal. Association between these factors and implant removal was evaluated. Results: Of 22 partial carpal arthrodesis, 12 (55%) had implant removal due to persistent lameness and 9/12 (75%) returned to full and acceptable function after implant removal. Indications for implant removal were implant interference (8), infection (4), and migration (1). When comparing type of implant, there was a significant difference when observing implant removal rates (p = 0.04). All 5 dogs with pins and wires (100%) required implant removal. Of 17 dogs with a plate, 7 (41.2%) required implant removal. Implant removal was performed on average 114 days post-operative. Discussion: Implant removal after partial carpal arthrodesis was frequent and was commonly indicated due to pin and wire fixation or plate implant interference. This study may impact how we prepare clients for potential post-operative complications and implant removal when recommending partial carpal arthrodesis.

Clinical outcomes of canine total hip replacement utilizing a BFX lateral bolt femoral stem: 195 consecutive cases (2013-2019).

OBJECTIVE: To evaluate the clinical outcomes of total hip replacements (THR) utilizing a BFX lateral bolt stem in dogs with coxofemoral joint disease. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: A total of 149 dogs representing 195 THR. METHODS: Consecutive THRs utilizing a BFX lateral bolt stem were studied. Preoperative, immediate postoperative, 1-, 2-, 3-, 4-, and 12-month postoperative radiographs were performed. All major and minor complications, revisions, outcomes, subsidence, canal flare index (CFI) were recorded. RESULTS: An intraoperative complication rate of 11.8% was observed. The postoperative complication rate was 13.6%, with 9.2% major and 4.4% minor complications. Complications included: postoperative femur fractures (3.6%), coxofemoral luxation (3.6%), stem failure (0.5%), septic loosening (0.5%), aseptic loosening (0.5%), and acetabular fracture (0.5%). Three dogs underwent prophylactic plating after subjective assessment of cortical thickness. Five of 195 (2.6%) cases underwent explant of their prostheses (median = 3 months). Mean stem subsidence at 1 month postoperatively was 1.22 ± 0.16 mm. An increased CFI was associated with postoperative femur fractures (p < .05). A total of 190 of 195 (97.4%) cases returned to normal function in the long-term follow-up period. CONCLUSION: Use of the BFX lateral bolt stem resulted in minimal postoperative subsidence, a low femoral stem complication rate, and a high rate of achieving normal limb function. CLINICAL SIGNIFICANCE: The BFX lateral bolt stem should be considered in canine THR as the femoral failure rate is low and the long-term success rate is high.

Canine Elbow Dysplasia: Medial Compartment Disease and Osteoarthritis.

Erosion of the articular cartilage of the medial compartment of the elbow (the humeroulnar articulation) secondary to incongruency associated with elbow dysplasia or traumatic injury has been termed, medial compartment disease. When nonsurgical strategies to manage osteoarthritis (OA) fail, surgical solutions may be warranted. Surgical strategies reduce pain through off-loading of the medial compartment by load-shifting osteotomies of the humerus or ulna. Other strategies involve replacement of portions or all of the articular surface of the medial compartment. With global elbow joint OA (medial and lateral compartment), a total elbow replacement may be required.

The Effects of Interlocking a Universal Hip Cementless Stem on Implant Subsidence and Mechanical Properties of Cadaveric Canine Femora.

OBJECTIVE: To determine if an interlocking bolt would limit subsidence of the biological fixation universal hip (BFX(®)) femoral stem under cyclic loading and enhance construct stiffness, yield, and failure properties. STUDY DESIGN: Ex vivo biomechanical study. ANIMALS: Cadaveric canine femora (10 pairs). METHODS: Paired femora implanted with a traditional stem or an interlocking stem (constructs) were cyclically loaded at walk, trot, and gallop loads while implant and bone motions were captured using kinematic markers and high-speed video. Constructs were then loaded to failure to evaluate failure mechanical properties. RESULTS: Implant subsidence was greater (P = .037) for the traditional implant (4.19 mm) than the interlocking implant (0.78 mm) only after gallop cyclic loading, and cumulatively after walk, trot, and gallop cyclic loads (5.20 mm vs. 1.28 mm, P = .038). Yield and failure loads were greater (P = .029 and .002, respectively) for the interlocking stem construct (1155 N and 2337 N) than the traditional stem construct (816 N and 1405 N). Version angle change after cyclic loading was greater (P = .020) for the traditional implant (3.89 degrees) than for the interlocking implant (0.16 degrees), whereas stem varus displacement at failure was greater (P = .008) for the interlocking implant (1.5 degrees) than the traditional implant (0.17 degrees). CONCLUSION: Addition of a stabilizing bolt enhanced construct stability and limited subsidence of a BFX(®) femoral stem. Use of the interlocking implant may decrease postoperative subsidence. However, in vivo effects of the interlocking bolt on osseointegration, bone remodeling, and stress shielding are unknown.

Femoral prosthesis version angle calculation from a sagittal plane radiographic projection of the femur.

OBJECTIVE: To investigate a technique for determination of femoral prosthesis version using a mediolateral radiographic projection of the sagittal plane of the implanted femur. STUDY DESIGN: In vitro radiographic study. METHODS: Femoral prostheses from BioMedtrics (cemented [CFX™] and biologic fixation [BFX™]), and Kyon uncemented were secured in prepared Sawbones® at various angles of version. Axial and mediolateral radiographs of the implanted femurs were taken at each angle of version. Angles of version were determined by direct measurement from the axial view, and then calculated from measurements made on the lateral view by 2 separate observers blinded to the axial measurement. Accuracy of the technique was evaluated individually for each observer using regression analysis. Inter-observer mean values were assessed with a paired t-test, and the within and between operator error was evaluated using percent coefficient of variance (%CV). RESULTS: There was no significant difference between the directly measured prosthesis version and the calculated prosthesis version (P > .05). There was no significant difference between the mean measured inclination angle (MIA) measured by each observer (P = .204). Mean version angles measured were accurate at all version angles for both observers; %CV < 15%. CONCLUSION: Femoral prosthesis version angles can be accurately determined using this technique.

Assessment of acetabular cup positioning from a lateral radiographic projection after total hip replacement.

OBJECTIVE: To demonstrate first that a ventrodorsal radiographic (VDR) projection is inadequate for obtaining accurate acetabular cup position (ACP) measurements after total hip replacement (THR), and second to validate use of the lateral radiographic (LR) projection to measure ACP. STUDY DESIGN: In vitro study. METHODS: Eleven VDRs were obtained after insertion of a cup into the acetabulum of a Sawbones pelvis fixed at an approximated angle. For each VDR, the pelvis was placed in varying degrees of craniocaudal pelvic tilt (CCPT). Fifteen LRs were obtained of a Sawbones pelvis with varying ACPs. Five blinded observers made previously described measurements of ACP on each VDR and angle of lateral opening (ALO) and coronal retroversion (CR) on each LR. RESULTS: An almost perfect level of agreement was observed between 5 observers for the repeatability of both VDR and LR measurements. When varying degrees of CCPT were introduced, there was no agreement in the measurements of ACP from VDRs. In all cases, and at all ACPs, measurements taken from LRs were in agreement. CONCLUSION: Undetectable CCPT causes significant variability in ACP measurements on VDRs predisposing postoperative radiographic measurements to inaccuracy. Measurements obtained from an LR of CR and ALO are accurate and consistent between observers and it should be used to measure ACP. The VDR should be performed to assess bone and implant integrity but not to obtain measurements of ACP because of CCPT causing measurements to be unreliable. Measurements of ACP obtained from an LR in conjunction with femoral anteversion may allow for investigation of the influence of ACP on coxofemoral joint luxation after THR.

Evaluation of the effect of distal femoral elevation on radiographic measurement of the anatomic lateral distal femoral angle.

OBJECTIVE: To determine the effect of elevation of the distal femur on radiographic determination of the anatomic lateral distal femoral angle (aLDFA) in an in vitro canine model. STUDY DESIGN: In vitro study. SAMPLE POPULATION: Cadaveric canine femora (n = 7 pairs). METHODS: Dissected femora were positioned in a custom-mounting frame. The distal end of the frame was elevated in 5° increments from 0° to 45°, with craniocaudal (CrCd) radiographs obtained at each position. The aLDFA was measured from the radiograph of each femur at each elevation. Statistical comparison of measured values was performed and radiographs were evaluated for radiographic indicators of positioning. RESULTS: There was significant increase in measured aLDFA at all elevations >5° when compared to 0° elevation. The mean value for aLDFA increased from 92.3° at 0° elevation to 95.0° at 45° elevation. The femoral trochlear ridges and walls of the intercondylar fossa were identified as the most useful radiographic landmarks. The fabellae, though extrafemoral and inconsistently retained in the current study, may also be beneficial. The lesser trochanter and nutrient foramen were less useful landmarks because of anatomic variability. CONCLUSION: Elevation of the distal femur had a significant effect on measured aLDFA at all elevations greater than 5°.

Evaluation of the effect of pelvic tilt in the coronal plane on the Norberg angle measured in ventrodorsal radiographic views of a canine hip joint bone model.

OBJECTIVE: To determine the effect of pelvic tilt on the Norberg angle (NA) measured in ventrodorsal radiographic views of a hip joint in a canine femoral-pelvic bone model. SAMPLE POPULATION: Radiographic views of a femoral-pelvic bone model with 1 articulated hip joint (without evident laxity). PROCEDURES: The bone model was placed on a radiography table. With the joint fully extended, the pelvic coronal plane was tilted from 0° in 5° increments caudally and cranially to a maximum of 30° in each direction (femoral frontal plane was maintained parallel with the radiograph cassette); a digital ventrodorsal radiographic view was obtained at each tilt position. In each image, the NA was measured 3 times by 2 observers (operators). The effect of pelvic tilt on the NA was evaluated by use of a repeated-measures analysis; within-and between-operator variances were also assessed. RESULTS: Within-operator repeatability was excellent for assessments of hip joint NAs in radiographic views obtained when cranial or caudal tilt was applied to the femoral-pelvic model; replicate measurement variation was < 2.5% (coefficient of variation < 5%). Mean NA values determined by the 2 operators in cranial or caudal tilt views did not differ. Mean between-operator difference in caudal tilt measurements was -0.55° (95% confidence interval, -1.69° to 0.59°) and in cranial tilt measurements was -0.13° (95% confidence interval, -1.33° to 1.06°). Cranial or caudal pelvic tilt did not affect measurement of the NA. CONCLUSIONS AND CLINICAL RELEVANCE: Model-derived results indicated that pelvic tilt during acquisition of ventrodorsal radiographic views of the hip joints of a dog should not affect measurement of the NA.

Determination of the mechanical medial proximal tibial angle using a tangential radiographic technique.

OBJECTIVE: To assess whether there is a difference in the mechanical medial proximal tibial angle (mMPTA) measured on a tangential caudocranial (tCdCr) radiographic projection versus a straight caudocranial (sCdCr) projection before and after inducing a varus deformity in the proximal tibia. STUDY DESIGN: In vitro study. SAMPLE POPULATION: Cadaveric canine tibiae (n=4 pair). METHODS: For each tibia, a mediolateral radiographic projection was performed and the tibial plateau angle was measured. sCdCr and tCdCr radiographic projections were obtained and the mMPTA measured. A varus deformity was created in the proximal aspect of the tibia and sCdCr and tCdCr projections were repeated and mMPTA measured. RESULTS: mMPTA for tCdCr was statistically different from mMPTA for the sCdCr projection for the varus tibiae (P<.05). There was no significant difference in the mMPTA measured on the sCdCr projections before and after creation of a varus deformity (P>.05). There was a significant difference in mMPTA measured on the tCdCr projection before and after creation of a varus deformity (P<.05). CONCLUSION: Varus deformity in the mMPTA was identified on tCdCr projections of the varus tibiae whereas it was not identified on sCdCr projections. CLINICAL RELEVANCE: Tangential radiographic projections of the tibial plateau may be useful for evaluating varus deformities involving the articular surface of the tibia and should be performed during preoperative evaluation of angular limb deformities involving the proximal aspect of the tibia and for tibial plateau leveling osteotomy (TPLO) planning.