Stanley E. Kim

Tibial Osteotomies for Cranial Cruciate Ligament Insufficiency in Dogs

OBJECTIVE To review the biomechanical considerations, experimental investigations, and clinical data pertaining to tibial osteotomy procedures for treatment of cranial cruciate ligament (CrCL) insufficiency in dogs. STUDY DESIGN Literature review. METHODS Literature search through Pub Med, Veterinary Information Network, Commonwealth Agricultural Bureau Abstracts, and conference proceedings abstracts (November 1977 to March 2007). RESULTS Reported tibial osteotomy procedures attempt to eliminate sagittal instability (cranial tibial thrust) in CrCL-deficient stifles by altering the conformation of the proximal tibia. Functional stability can be achieved by decreasing the tibial plateau slope (cranial tibial closing wedge osteotomy [CTWO], tibial plateau leveling osteotomy [TPLO], combined TPLO and CTWO, proximal intraarticular osteotomy, chevron wedge osteotomy), altering the alignment of the patellar tendon (tibial tuberosity advancement), or both (triple tibial osteotomy). Clinical reports assessing the efficacy of these procedures frequently use subjective outcome measures, and the periods of follow-up evaluation are highly variable. Satisfactory results have been reported in most (>75%) dogs irrespective of the type of tibial osteotomy procedure. CONCLUSIONS Currently available data does not allow accurate comparisons between different tibial osteotomy procedures, or with traditional methods of stabilizing the CrCL-deficient stifle. Carefully designed long-term clinical studies and further biomechanical analyses are required to determine the optimal osteotomy technique, and whether these procedures are superior to other stabilization methods. CLINICAL RELEVANCE Limb function in dogs with CrCL insufficiency can be improved using the currently described tibial osteotomy techniques.

Effect of tibial plateau leveling osteotomy on femorotibial contact mechanics and stifle kinematics.

OBJECTIVE To evaluate the effects of tibial plateau leveling osteotomy (TPLO) on femorotibial contact mechanics and 3-dimensional (3D) 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 degrees. Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TPLO-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 mechanical variables were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and increased internal tibial rotation in the CrCL-deficient stifle. No significant differences in 3D femorotibial alignment were observed between normal and TPLO-treated stifles; however, femorotibial contact area remained significantly smaller and peak contact pressures in both medial and lateral stifle compartments were positioned more caudally on the tibial plateau, when compared with normal. CONCLUSION Whereas TPLO eliminates craniocaudal stifle instability during simulated weight bearing, the procedure fails to concurrently restore femorotibial contact mechanics to normal. CLINICAL RELEVANCE Progression of stifle osteoarthritis in dogs treated with TPLO may be partly the result of abnormal stifle contact mechanics induced by altering the orientation of the proximal tibial articulating surface.

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 degrees . 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.

Effect of tibial plateau leveling osteotomy on femorotibial subluxation: in vivo analysis during standing.

OBJECTIVE To assess the effect of tibial plateau leveling osteotomy (TPLO) on femorotibial subluxation during standing in dogs with cranial cruciate ligament (CrCL) insufficiency. STUDY DESIGN Prospective clinical study. ANIMALS Fifteen dogs weighing 20-45 kg with unilateral complete CrCL insufficiency. METHODS Force-platform analysis, and lateral weight-bearing radiographs of the affected stifle were acquired preoperatively, 1, 3, and 6 months postoperatively. The distance between the origin and insertion of the CrCL (CrCL(d) ) was measured on each radiograph and compared between time points using ANOVA. Lateral radiographs of the non-weight-bearing affected stifle and weight-bearing contralateral normal stifle were acquired preoperatively, and CrCL(d) was compared with a paired t-test. Dogs were grouped according to medial meniscal status (intact or hemimeniscectomy) and CrCL(d) was compared within each group using ANOVA. RESULTS No difference was observed in CrCL(d) between the non-weight-bearing affected stifle and the contralateral stifle (P = .994). That is, femorotibial joint alignment in the affected stifle when non-weight-bearing was considered normal. Preoperatively in the affected stifle, CrCL(d) during weight-bearing was 6.3 ± 2.4 mm longer than normal (P < .001). Postoperative weight-bearing CrCL(d) in dogs with intact menisci at all time points was not statistically different from normal; CrCL(d) at 1 (P = .014) and 6 months (P = .005) postoperatively was longer than normal in dogs with hemimeniscectomy. CONCLUSIONS TPLO does not consistently resolve femorotibial subluxation during standing in dogs with CrCL insufficiency. The medial meniscus appears to be an important contributor to stability in stifles treated by TPLO.

Effect of cranial cruciate ligament deficiency, tibial plateau leveling osteotomy, and tibial tuberosity advancement on contact mechanics and alignment of the stifle in flexion.

OBJECTIVE To assess contact mechanics and 3-dimensional (3-D) joint alignment in cranial cruciate ligament (CCL)-deficient stifles before and after tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA) with the stifle in 90 degrees of flexion. STUDY DESIGN In vitro biomechanical study. SAMPLE POPULATION Cadaveric pelvic limb pairs (n=8) from dogs weighing 28-35 kg. METHODS Contralateral limbs were assigned to receive TPLO or TTA. Digital pressure sensors were used to measure femorotibial contact area, peak and mean contact pressure, and peak pressure location with the limb under a load of 30% body weight and stifle flexion angle of 90 degrees . 3-D poses were obtained using a Microscribe digitizer. Specimens were tested under normal, CCL deficient, and treatment conditions. RESULTS Significant disturbances in alignment were not observed after CCL transection, although medial contact area was 10% smaller than normal (P=.003). There were no significant differences in contact mechanics or alignment between normal and TTA conditions; TPLO induced 6 degrees varus angulation (P<.001), 26% decrease in lateral peak pressure (P=.027), and 18% increase in medial mean pressure (P=.008) when compared with normal. CONCLUSION Cranial tibial subluxation is nominal in CCL-deficient stifles loaded in flexion. Stifle alignment and contact mechanics are not altered by TTA, whereas TPLO causes mild varus and a subsequent increase in medial compartment loading. CLINICAL RELEVANCE Cranial tibial subluxation of CCL-deficient stifles may not occur during postures that load the stifle in flexion. The significance of minor changes in loading patterns after TPLO is unknown.

Comparison of 5 surgical techniques for partial liver lobectomy in the dog for intraoperative blood loss and surgical time.

OBJECTIVE To compare surgical time and intraoperative blood loss for 5 partial liver lobectomy techniques in the dog. STUDY DESIGN Experimental in vivo study. ANIMALS Dogs (n=10). METHODS Five surgical techniques (SurgiTie(™) ; LigaSure(™) ; Ultracision(®) Harmonic Scalpel [UAS]; Suction+Clip; Suction+thoracoabdominal stapler [TA]) for partial liver lobectomy in dogs were evaluated and compared for total surgical time and intraoperative blood loss. Body weight, activated clotting time (ACT), heart rate, and intraoperative blood pressure (BP) were recorded. Blood loss was determined by adding the weight of the blood soaked sponges during surgery (1 g=1 mL) to the amount of suctioned blood (mL). Surgical time (in seconds) was determined from the start of the lobectomy until cessation of bleeding from the stump. Mean surgical time and mean blood loss for each technique were compared using a Tukeys multiple comparison test. RESULTS No significant differences were found between dogs for weight, ACT, heart rate, and intraoperative BP. No complications were seen with the SurgiTie(™) technique in 9 of 10 cases. There was no significant difference in surgical time between techniques however there was a significant difference for blood loss; the Suction+Clip method had significantly more blood loss than the other techniques. CONCLUSIONS Skeletonization of the lobar vessels before individually clipping them (Suction+Clip) resulted in a higher blood loss than using Suction+TA, UAS, SurgiTie(™) or the LigaSure(™) device. The SurgiTie(™) appears to be an acceptable method for partial liver lobectomy. CLINICAL RELEVANCE Although skeletonization and individually clipping the vessels had the highest blood loss, it still was <7.5% of total blood volume. All 5 techniques should be safe for clinical use in small to medium sized dogs up to 26 kg.

In vivo femorotibial subluxation during weight-bearing and clinical outcome following tibial tuberosity advancement for cranial cruciate ligament insufficiency in dogs.

Ex vivo studies have been used extensively to investigate the mechanisms of tibial osteotomies but few have explored femorotibial alignment in vivo. The aim of this study was to assess femorotibial joint alignment under static weight-bearing conditions (and subsequent outcome) in dogs treated for cranial cruciate ligament (CrCL) insufficiency with tibial tuberosity advancement (TTA). Twenty-five dogs (30 stifles) with CrCL insufficiency treated by TTA were included. The distance from the origin to insertion of the CrCL (CrCLd) was measured on non-weight-bearing immediate post-operative radiographs and weight-bearing follow-up radiographs. CrCLd values were compared using a paired t test. The relationship between change in CrCLd (ΔCrCLd) and post-operative patellar tendon angle according to the common tangent method (PTACT) was assessed using Pearsons correlation. Outcome was assessed with an owner-completed questionnaire, and peak vertical force (PVF) and vertical impulse (VI) as percentages of bodyweight (BW). Following TTA, 21/30 stifles were persistently subluxated at a follow-up of 18 ± 14 months (mean ± SD). Follow-up weight-bearing CrCLd was greater (P<0.001) than post-operative non-weight-bearing CrCLd, with a mean ΔCrCLd of 5.8 ± 3.4mm (16 ± 10%). Post-operative PTACT was 89 ± 3° and did not correlate with ΔCrCLd (r=0.002, P=0.994). Mean PVF and VI were 65 ± 10% BW and 9±2% BW, respectively. All owners felt TTA provided improvement in lameness. The results indicated that TTA does not normalize sagittal plane femorotibial stability during standing at a PTACT of 90°, but most dogs return to good limb function regardless of femorotibial alignment.

Effect of Transection of the Caudal Menisco‐Tibial Ligament on Medial Femorotibial Contact Mechanics

OBJECTIVE To evaluate the effect of transection of the medial caudal menisco-tibial ligament on contact mechanics in a canine cadaveric model of cranial cruciate ligament (CCL) rupture and tibial plateau leveling osteotomy (TPLO). STUDY DESIGN Ex vivo biomechanical study. SAMPLE POPULATION Unpaired pelvic limbs (n=8) from 28-35 kg dogs. METHODS Cadaveric pelvic limbs with CCL-deficient stifles stabilized with TPLO were axially loaded using a material testing machine with 30% body weight and a stifle angle of 135 degrees. Medial compartment femorotibial contact force and area, peak and mean contact pressure, and peak pressure location were measured with pressure sensors. A paired t-test was used for comparison; P<.05 was considered significant. RESULTS Transection of the caudal menisco-tibial ligament resulted in a significant decrease in contact area, from 145 +/- 24 to 71 +/- 25 mm(2) (P<.001) and a significant increase in peak pressure magnitude from 2.9 +/- 0.4 to 4.1 +/- 0.5 MPa (P<.001). Transection of the caudal menisco-tibial ligament caused a significant increase in load in the caudal portion of the medial compartment (P<.001). CONCLUSIONS Our results suggest that transecting the caudal menisco-tibial ligament eliminates the load bearing function of the medial meniscus and results in significant changes in medial femorotibial contact mechanics. CLINICAL RELEVANCE The abnormal cartilage contact stresses after transection of the caudal menisco-tibial ligament may have a negative impact on the cartilage homeostasis and predispose to further degeneration of the medial compartment after TPLO.

Comparison of computed tomographic angiography and ultrasonography for the detection and characterization of portosystemic shunts in dogs.

The purpose of this retrospective study was to compare the accuracy of computed tomographic angiography (CTA) and abdominal ultrasonography in detecting and characterizing portosystemic shunts (PSS) in dogs. Medical records of 76 dogs that underwent CTA and/or abdominal ultrasonography suspected to have PSS were reviewed. Presence or absence, and characterization of PSS (when present) on CTA were reviewed by a board-certified veterinary radiologist that was blinded to the clinical findings. The abdominal ultrasonography findings were reviewed from the medical records. Visualization and description of the origin and insertion of PSS on CTA and abdominal ultrasonography were related with laboratory, surgical, or mesenteric portographic confirmation of the presence or absence of PSS. The sensitivity for detection of PSS with CTA (96%) was significantly higher than abdominal ultrasonography (68%; P < 0.001). The specificities for CTA and abdominal ultrasonography were 89% and 84%, respectively (P = 0.727). Computed tomographic angiography detected the correct origin in 15 of 16 dogs and correct insertion in 15 of 16 dogs with congenital PSS. Abdominal ultrasonography detected the correct origin in 24 of 30 dogs and correct insertion in 20 of 33 dogs with congenital PSS. Multiple acquired PSS were seen in four of five dogs and in one of six dogs on CTA and abdominal ultrasonography, respectively. Computed tomographic angiography was 5.5 times more likely to correctly ascertain the presence or absence of PSS when compared to abdominal ultrasonography (P = 0.02). Findings indicated that CTA is a noninvasive diagnostic modality that is superior to abdominal ultrasonography for the detection and characterization of PSS in dogs.

Contact mechanics and three-dimensional alignment of normal dog elbows.

OBJECTIVE To evaluate the effects of antebrachial rotation at 3 elbow flexion angles on contact mechanics and 3-dimensional (3D) alignment of normal dog elbows. STUDY DESIGN Ex vivo biomechanical study. ANIMALS Unpaired thoracic limbs from 18 dogs (mean ± SD weight, 27 ± 4 kg). METHODS With the limb under 200 N axial load, digital pressure sensors measured contact area (CA), mean contact pressure (MCP), peak contact pressure (PCP), and PCP location in the medial and lateral elbow compartments, and 3D static poses of the elbow were obtained. Each specimen was tested at 115°, 135°, and 155° elbow flexion, with the antebrachium in a neutral position, in 28° supination, and in 16° pronation. Repeated measure ANOVAs with post-hoc Bonferroni (P ≤ .0167) were performed. RESULTS Both pronation and supination decreased CA by 16% and 8% and increased PCP by 5% and 10% in the medial and lateral compartments, respectively. PCP location moved 2.3 mm (1.8-3.2 mm) closer to the apex of the medial coronoid process in pronation and 2.0 mm (1.8-2.2 mm) farther away in supination. The radial head and medial coronoid process rotated 5.4° and 1.9° internally during pronation and 7.2° and 1.2° externally during supination. CONCLUSIONS Contact mechanics and 3D alignment of normal dog elbows varied significantly at different elbow poses.