Medial Meniscal Release Research Articles

Effect of center of rotation of angulation-based levelling osteotomy on instantaneous center of rotation ex vivo

Cranial cruciate ligament rupture is a common cause of femorotibial instability in dogs. Despite numerous techniques being described for achieving joint stabilization, no consensus exists on the optimal management strategy. This ex vivo study utilized the path of the instantaneous center of rotation (ICR) to compare normal, pathological and treated joints. Fluoroscopic recordings of seven limbs from a previous study of canine stifle joint stability following center of rotation of angulation-based levelling osteotomy (CBLO) with and without hamstring loading were analyzed using least-squares approximation of the ICR and estimation of percentage gliding (vs. rolling) to determine if alterations in ICR path and gliding caused by CCL transection and following meniscal release could be normalized by CBLO. In intact joints, the ICR path was located mid-condyle, but this shifted significantly proximally and caudally following CCL transection and medial meniscal release (p < 0.007, p < 0.04). Hamstring loading resulted in qualitative and some quantitative improvements in joint movement based on percentage gliding movement analysis. The ICR path after CBLO remained significantly different to the intact location with or without a hamstring load (p < 0.02, p < 0.04), potentially consistent with CBLO aims of mild residual instability. CBLO resulted in percentage gliding characteristics not significantly different to intact joints (p > 0.08). Qualitative improvements in ICR path and percentage gliding quantities and variability suggest that hamstring loading positively influences joint biomechanics and that further investigation of this role ex vivo and clinically is warranted.

Instantaneous center of rotation in the canine femorotibial joint: Ex vivo assessment of a tool to evaluate joint stabilization surgeries

Cranial cruciate ligament rupture is a common cause of femorotibial joint instability in the dog. Numerous techniques including several tibial osteotomies have been described for stabilization, but there is no current consensus on the best method. The instantaneous center of rotation (ICR) can aid investigations of pathological joint movement, but its use is problematic in the femorotibial joint due to combined rotation and translation during flexion and extension. Using fluoroscopic images from an earlier cadaveric study of canine joint stability, an interpolation method was used to create repeatable rotational steps across joint situations, followed by least squares approximation of the ICR. The ICR in intact joints was located mid-condyle but displaced significantly (P < 0.001) proximally following cranial cruciate ligament transection and medial meniscal release. Individual joints appear to respond differently to destabilization. Triple tibial osteotomy partially restored ICR location during early movement from flexion to extension. Joint instability significantly altered the proportions of rolling and gliding movement at the joint surface (P < 0.02), which triple tibial osteotomy partially improved. While triple tibial osteotomy restores joint stability ex vivo and clinically, normal biomechanics of the joint are not restored. The methods described here may prove useful for comparison of osteotomy techniques for stabilization of the cranial cruciate ligament deficient femorotibial joint in dogs.

Treatment-Monitoring Capabilities of Serum and Urine Biomarkers for Meniscal Allograft Transplantation in a Preclinical Canine Model

Background: Meniscal allograft transplantation (MAT) has been developed as a treatment for meniscal deficiency. Despite promising outcomes, there are no real-time methods to evaluate graft survivorship and predict functional outcomes. Hypothesis: Assessment of serum and urine biomarkers could be used to develop biomarker panels—prognostic (1- and 3-month postsurgical time points) and diagnostic (6-month time point)—based on strong associations with clinically relevant outcome metrics obtained 6 months after surgery. Study Design: Descriptive laboratory study. Methods: Twelve adult purpose-bred research hounds were included and underwent medial meniscal release to induce meniscal deficiency. Three months after meniscal release surgery, medial menisci were replaced with fresh-frozen meniscus (n = 4), fresh meniscus (n = 4), or fresh meniscotibial osteochondral allograft (n = 4) such that a spectrum of pain and functional outcomes could be anticipated. Serum and urine from all dogs were collected preoperatively and at 1, 3, and 6 months after MAT surgery. Dogs were assessed for pain-related and functional outcomes at the same time points. To develop a prognostic panel of biomarkers, biomarker data from the 1- and 3-month post-MAT surgery time points were used to model 6-month clinical outcomes. A diagnostic panel of biomarkers was developed using data from the 6-month post-MAT surgery to model 6-month clinical outcomes. Primary outcomes for pain and function were visual analog scale (VAS) and operated limb percentage total pressure index (%TPI), respectively. Using random subject effects, linear mixed models were used to develop prognostic biomarker panels, and linear fixed-effect models were used to develop diagnostic biomarker panels, with variance explained for each panel reported (R2) along with individual biomarker relationships. Results: Across prognostic biomarker panels, a panel including serum IL-6, IL-8, IL-10, and IL-18 was fit for the primary functional outcome, operated limb %TPI (R2 = 0.450), whereas a panel including serum CTX-II and OPG was fit for the primary pain-related outcome, VAS (R2 = 0.516). Across diagnostic biomarker panels, a panel including serum MMP-1 and MMP-3 and urine PINP and TIMP-1 was fit for %TPI (R2 = 0.863). Separately, a panel including urine CTX-I, CTX-II, IL-8, MMP-2, and TIMP-1 was fit as diagnostic biomarkers for the VAS for pain (R2 = 0.438). Conclusion: Biomarker panels of selected serum and/or urine proteins can model clinically relevant metrics for function and pain in a preclinical model of MAT. Clinical Relevance: Biomarker panels could be used to provide real-time diagnostic and prognostic data regarding outcomes after MAT.

Paper 33: Serum and Urine Biomarkers for Treatment Monitoring after Meniscal Allograft Transplantation in a Preclinical Canine Model

Objectives:To analyze serum and urine biomarker concentrations for their capabilities in delineating differences in assessments of pain and functional outcomes after meniscus allograft transplantation (MAT) in a preclinical canine model. The study was designed to test the hypothesis that serum and urine biomarkers could be used for prognostic (1- and 3-month post-surgical time points) and diagnostic (6-month time point) assessments, based on strong associations with clinically relevant pain and function outcomes after MAT.Methods:Twelve adult, purpose-bred research hounds were included and underwent medial meniscal release (MR) to induce medial compartment gonarthrosis. Three months following MR, medial MAT was performed using: fresh-frozen meniscus (n=4), fresh meniscus (n=4), or fresh menisco-tibial OCA (n=4). Serum and urine from all dogs were collected preoperatively and at 1, 3, and 6 months following MAT. Validated outcome measures for pain, function, effusion, knee range of motion, and gait kinetics were collected at these same timepoints. To develop a prognostic panel of biomarkers, biomarker data from the 1-month and 3-month post-MAT surgery timepoints were used to model 6-month outcomes. A diagnostic panel of biomarkers was developed using biomarker data from the 6-month post-MAT surgery to model 6-month outcomes.Results:Across prognostic biomarker panels, serum biomarkers were mainly represented. A panel including serum IL-6, IL-8, IL-10, and IL-18 had strong model fit for prognostication of the gait kinetics outcome, operated limb %Total Pressure Index (%TPI) (R2=.45). Whereas, a biomarker panel including serum CTX-II and OPG had strong model fit for prognostication of the primary pain-related outcome, VAS pain (R2=.52). Across diagnostic biomarker panels, a panel including serum MMP-1 and MMP-3 and urine PINP and TIMP-1 had strong model fit as diagnostic biomarkers for %TPI (R2=.86). Whereas, a panel including urine CTX-I, CTX-II, IL-8, MMP-2, and TIMP-1 had strong model fit as diagnostic biomarkers for VAS pain (R2=.44).Conclusions:Biomarker panels of selected serum and/or urine proteins highly correlate with clinically-relevant metrics for pain and function outcomes in a preclinical model of meniscus allograft transplantation.

Effect of center of rotation of angulation-based leveling osteotomy on ex vivo stifle joint stability following cranial cruciate ligament transection and medial meniscal release with and without a hamstring load.

ObjectiveTo evaluate the effect of center of rotation of angulation (CORA)‐based leveling osteotomy (CBLO) and hamstring load on stifle stability following cranial cruciate ligament transection (CCLx) and medial meniscal release (MMR).Study designEx vivo experimental study.Sample populationCadaver hind limb preparations (n = 7).MethodsAfter instrumentation, constant quadriceps and gastrocnemius loads with an optional hamstring load in a 3:1:0.6 ratio were applied, and stifles were extended from fully flexed using an electrical motor during fluoroscopic recording. The recording process was repeated after each of CCLx, MMR and CBLO and the extracted landmark coordinates were used for calculation of cranial tibial translation (CTT) and patellar ligament angle (PTA).ResultsMean initial tibial plateau angle was 28.1°: post‐CBLO the mean was 9.7°. Cranial tibial translation developed from 50° and 75° with CCLx and MMR respectively (p < .04, < .02) without hamstring loading. Hamstring loading mitigated CTT due to CCLx and delayed CTT until 120° for MMR (P < .02) in this model. CBLO prevented CTT, except at 140° without hamstring loading (P = .01). Similar results were seen for PTA, but CBLO curves were parallel to and lower than intact values at all tested angles (P < .04), consistent with induced effective joint flexion.ConclusionCBLO to a target tibial plateau angle of 10° largely eliminated CTT induced by CCLx and MMR. Hamstring loads of 20% quadriceps load improved stifle stability in this model.ImpactStifle stability following CBLO appears to be multifactorial and depends on meniscal integrity, joint angle, and hamstring strength.

A retrospective evaluation of complications associated with forkless tibial tuberosity advancement performed in primary care practice.

To report postoperative complications associated with forkless tibial tuberosity advancement (TTA) performed in primary care veterinary practice and to compare results with previous publications. Retrospective study. Three hundred seventy-four forkless TTAs in 329 dogs performed by six nonspecialist veterinarians. Medical records of dogs treated with a standard forkless TTA (2013-2016) and with at least 12 months of postoperative follow-up were reviewed. Complications recorded by the referring practice or the operating veterinarian were classified as minor (medically treated) or major (surgically treated). Complications occurred in 57 of 374 (15.2%) TTAs; 28 (7.5%) complications were major, and 29 (7.7%) complications were minor. Postliminary meniscal injuries were documented in 12 of 374 (3.2%) TTAs (12/57 major complications) and were more common when the ratio of cage size to bodyweight was ≤0.25 (P = .019). Mean TTA (cage size) was greater in this population than what has been previously reported for a lower median bodyweight. The incidence of major complications was low and within the range previously reported for TTA in referral practice after adjusting for study design. The magnitude of advancement was greater, and the incidence of postliminary meniscal injury was lower than what has been previously reported, after accounting for dogs that had a preliminary meniscal injury or medial meniscal release. Forkless TTA may be successfully performed by experienced veterinarians in primary care practice with a low rate of complications. The incidence of postliminary meniscal injury may be reduced by a greater degree of advancement of the tibial tuberosity.

Intra-articular xenogeneic mesenchymal stem cell-based therapy increases CD4+CD25+ cells in synovial fluid

Osteoarthritis (OA) is a chronic joint disease afflicting a substantial portion of the world’s population with no currently available cure. Mesenchymal stem cell (MSC)-based therapies have been observed to have a mild beneficial effect in OA but the mechanism behind their action remains unclear. This study aimed to identify the lymphocytic response to a xenogeneic human umbilical cord-derived MSC-based cell therapy. A unilateral medial meniscal release model was employed in an ovine model of post-traumatic OA, with the contralateral limb employed as the control. A dose of 1.0 × 107 MSCs was administered to a subset of the OA group as well as to a normal sham-operated group. Synovial fluid was aspirated periodically for 13 weeks for flow cytometry analysis. At the termination of the study the stifle joints were collected and analyzed for potential pathologic changes. Cell therapy induced a transient influx of CD4+ leukocytes; there was a similar significant increase in the proportion of CD4+CD25+ and CD4+CD25hi leukocytes in response to cell therapy, the latter being a subset that may be composed of regulatory T cells. There was no significant effect of the cell therapy treatment on the proportion of synovial fluid-derived CD8+ cells or BAQ44A+ B cells. iNOS expression of intimal lining macrophages was evident but reduced in the cell therapy OA group suggesting macrophage phenotype transformation. There were no inflammatory or histological changes that could be attributed to the cell therapy. Cell therapy induced chemotaxis of CD4+ cells to the joint but these cells were not associated with pathological changes, despite their expression of activation markers (CD25+).

Modelling the Effects of Cranial Cruciate Ligament Transection, Medial Meniscal Release and Triple Tibial Osteotomy on Stability of the Canine Stifle Joint.

The aim of this study was to evaluate the ex vivo effects of sequential cranial cruciate ligament transection (CCLx), medial meniscal release (MMR) and triple tibial osteotomy (TTO) on canine stifle stability compared with the intact state, across a wide range of joint angles. Nine right hind limb preparations were instrumented to provide constant quadriceps and gastrocnemius loads in a 3:1 ratio, and extended from full flexion during fluoroscopic recording. Recordings were repeated after each of CCLx, MMR and TTO. Fluoroscopic landmarks were used to calculate tibial subluxation and patellar ligament angle. Medial meniscal release resulted in additional cranial tibial subluxation compared with CCLx. Triple tibial osteotomy restored stifle stability up to a joint angle of 125 degrees. The presence of the crossover angle could be inferred from the patellar ligament angle and subluxation curves. Our results suggest that in the cranial cruciate ligament-deficient stifle, the crossover angle at which loading shifts between the caudal and cranial cruciate ligaments is dependent on both loading and integrity of the medial meniscus. Triple tibial osteotomy improves stifle stability over a wide range of joint angles under a quadricep to gastrocnemius loading ratio of 3:1 by converting cranial tibial thrust to caudal tibial thrust, due to TTO increasing the amount of joint extension required to reach the crossover angle.

Immunoregulatory properties of I.A. mesenchymal stem cells are maintained in a xenogenic animal model

Purpose: Osteoarthritis is a chronic joint disease afflicting a significant portion of the world’s population with no currently available cure. Clinical trials using mesenchymal stem cell-based therapies have a positive effect on pain and quality of life in osteoarthritis but the mechanism of action remains unclear. This study aimed to identify the lymphocyte response to a xenogeneic human umbilical cord-derived MSC-based cell therapy in the face of osteoarthritis progression. Methods: A unilateral medial meniscal release model was employed in 14 sheep to create OA where n=7 sheep received I.A. cell therapy (OACT) in the operated knee and n=7 received saline as controls (OA). Another unoperated group (n=7) received cell therapy (CT Control). Three months later IA cell therapy consisting of 1.0× 107 Human SHC-MSCs* (Small Mesenchymal Stem Cells primed with Hypoxia and Calcium ions) was administered into the medial knee joint space. Synovial fluid was aspirated periodically for 13 weeks for flow cytometry analysis. At termination of the study, the stifle joints underwent macroscopic and histologic assessments using the OARSI histology scoring system for subchondral bone, cartilage and synovial membrane. Flow cytometry data was analyzed with a linear mixed effects model while pathology scores were analyzed by the Mann-Whitney U test and Wilcoxon signed rank test, with the Bonferroni correction for multiple comparisons. Results: There were no adverse reactions to the I.A. therapy. Cell therapy administration induced an influx of CD4+ leukocytes (Fig 1). Of these there was a significant increase in the proportion of CD4+CD25+ and CD4+CD25hi leukocytes; the CD4+CD25hi being subset that may be composed of regulatory T cells. There was no significant effect of the cell therapy treatment on the proportion of synovial fluid CD8+ cells or B cells (BAQ44A+), and B cells occurred in small numbers. Conclusions: Xenogeneic cell therapy did not trigger a classical host versus graft reaction leading to tissue injury. Cell therapy induced chemotaxis of CD4+ cells to the joint space but this was not associated with pathological change in tissues. Despite expression of activation markers (CD25+) these cells may regulate the immune response since CD4+cells can be sources of anti-inflammatory cytokines such as IL-4 and IL-10, as well as inhibiting the release of pro-inflammatory cytokines such as IL-1β or TNF-α. These findings support the notion that phenomena unrelated to long-term survival and engraftment of injected cells may have clear immunoregulatory effects.

Evaluation of an arthroscopic stifle lever for stifle joint distraction in toy breed dogs.

Arthroscopy has become an attractive modality in the diagnosis and treatment of joint diseases in toy breed dogs. However, the application of arthroscopy is limited by small joint space. Our objective was to evaluate the efficacy of a stifle lever for joint distraction during stifle arthroscopy in toy breed dogs. Paired stifles (n = 32 each) collected from 16 cadavers of toy breed dogs were randomly assigned to one of two groups: the stifle lever group or the external manipulation group. All stifles underwent arthroscopic cranial cruciate ligament transection, and the visualization of the medial meniscus was evaluated. Medial meniscal release (MMR) was then performed. Following arthroscopic examination, the success rates of MMR and damages of tibial and femoral cartilages were evaluated. Visualization of the medial meniscus was significantly better, and meniscal probing was significantly easier, in the stifle lever group than in the external manipulation group (p = 0.001). There were no significant differences between groups for MMR success or articular cartilage damage. Using the stifle lever on arthroscopic examination improved visualization and probing on the medial meniscus in toy breed dogs. The stifle lever can be used as a good modality in assessing medial meniscal pathology in toy breed dogs.

Major complications of tibial tuberosity advancement in 1613 dogs.

To report major postoperative complications in 1613 dogs with tibial tuberosity advancement (TTA). Retrospective case series. Dogs (n = 1613) with cranial cruciate ligament deficiency treated with TTA. Medical records of TTAs performed between December 2007-2013 were reviewed for age, sex, weight, contralateral stifle surgery, surgical approach, duration of preoperative lameness, presence of meniscal damage, concurrent patellar luxation and simultaneous bilateral TTA. Major postoperative complications were defined as surgical site infection (SSI) (superficial, deep, or organ/space), implant failure, fracture, patellar luxation, and meniscal tear. Major complications were recorded in 13.4% of cases. Superficial SSI (incisional irritation) was diagnosed in 6.9% cases, requiring only antimicrobial therapy. Other complications included postliminary medial meniscal tear (2% incidence), deep SSI (incisional dehiscence, 1.1%), implant failure (1%), patellar luxation (1.2%), fracture (0.9%), and organ/space SSI (septic arthritis, 0.4%). Dogs with normal menisci were less likely to develop postliminary meniscal tears if the medial meniscus was released at the time of TTA (P < .0001). No association was detected between recorded parameters and complications, although dogs >8 years old approached significance (P = .05) in terms of predisposition to major complications. Major complications after TTA are uncommon, even in dogs with concurrent patellar luxation or bilateral simultaneous procedures. In spite of its morbidity, medial meniscal release may prevent postliminary meniscal tears.

Feasibility of Stifle Medial Meniscal Release in Toy Breed Dogs with and without a Joint Distractor.

To investigate the feasibility of medial meniscal release (MMR) during stifle arthroscopy in toy breed dogs with and without a joint distractor. Experimental cadaveric study. Stifles (n = 40) from 20 canine cadavers (1.8-5.1 kg). Paired stifles were randomly assigned to the joint distractor group and the control group (n = 20 each). All stifles underwent arthroscopic transection of the cranial cruciate ligament followed by a release of the caudomedial meniscotibial ligament. After the procedures, all stifles were disarticulated. The degree of released meniscus was recorded subjectively by 5% increments. A MMR success was defined as a complete transection. The areas of femoral and tibial articular cartilage damage were calculated using india ink staining and digital imaging. The results were compared between groups and odds ratios were calculated. All stifle arthroscopies were successful. The success rate of MMR was significantly higher (P = .013) with a joint distractor than without a joint distractor. MMR was 7.4 times more likely to succeed with a joint distractor than without a joint distractor. The distal femoral articular cartilage was significantly more damaged (P = .011) in the stifles without a joint distractor than in the stifles with a distractor. No difference was found between the 2 groups for damage to the tibial cartilage (P = .058). Stifle arthroscopic MMR is feasible in toy breed dogs. Using a joint distractor is recommended for arthroscopic treatment based on our results because it significantly reduced the rate of incomplete release as well as iatrogenic cartilage damage.

Intra-articular administration of xenogeneic neonatal Mesenchymal Stromal Cells early after meniscal injury down-regulates metalloproteinase gene expression in synovium and prevents cartilage degradation in a rabbit model of osteoarthritis

The anti-inflammatory and anti-catabolic effects of neonatal Mesenchymal Stromal Cell (MSC) were investigated in a xenogeneic model of mild osteoarthritis (OA). The paracrine properties of MSC on synoviocytes were further investigated invitro. OA was induced by medial meniscal release (MMR) in 30 rabbit knees. A single early (day 3) or delayed (day 15) intra-articular (IA) injection of MSC isolated from equine Umbilical Cord Wharton's jelly (UC-MSC) was performed. Rabbits were euthanized on days 15 or 56. OA grading was performed and gene expression of inflammatory cytokines and metalloproteinases was measured in synovial tissue. Paracrine effects of UC-MSC were investigated using UC-conditioned vs control medium on rabbit primary synoviocytes stimulated with interleukin 1 beta invitro. No adverse local or systemic responses were observed clinically after xenogeneic UC-MSC injection. At study end point, cartilage fibrillation was lower in early treatment than in delayed treatment group. Cellular infiltrate was observed in the synovium of both UC-MSC groups. OA synovium exhibited a reduced expression of metalloproteinases-1, -3, -13 in the early cell-treated group at d56. Invitro, UC-conditioned medium exerted anti-inflammatory and anti-catabolic effects on synoviocytes exposed to pro-inflammatory stimulus. Early IA injection of equine UC-MSC was effective in preventing OA signs in rabbit knees following MMR. UC-MSC target the synovium and modulate the gene expression pattern of synoviocytes to promote an anti-catabolic environment. This confirms the synovium is a major target and mediator of MSC therapy, modulating the expression of matrix-degrading enzymes.

Surgical and postoperative complications associated with tibial tuberosity advancement for cranial cruciate ligament rupture in dogs: 458 cases (2007–2009)

To describe the surgical and postoperative complications encountered with tibial tuberosity advancement (TTA) performed in dogs with cranial cruciate ligament-deficient stifle joints. Retrospective case series. 458 dogs (TTA performed on 501 stifle joints). During the 2-year period, 624 TTA procedures had been performed in dogs for correction of cranial cruciate ligament deficiency. Five hundred one stifle joints in 458 dogs fit the criteria for inclusion; 43 dogs had had TTAs performed on both stifle joints. Historical data and complications reported were analyzed. Following 501 TTA surgeries, there were 95 instances of complications reported. In 7 stifle joints, 2 complications occurred. The most common complication was incisional infection and inflammation. Stifle joints with medial menisci that did not undergo medial meniscal release had a high incidence of subsequent injury, and meniscal tear was the most common complication treated by a second surgery. A partially torn cranial cruciate ligament left in situ at the time of TTA did not protect against subsequent injury of an intact, unreleased medial meniscus. Most fractures were identified on routine follow-up radiography and were rarely treated. In terms of preoperative factors, high body weight (> 40 kg [88 lb]) and a high preoperative patellar tendon angle were significantly associated with complications. High body weight and preoperative patellar tendon angle were significantly associated with complications following TTA in dogs. Subsequent meniscal tear was the most common reason for second surgery, suggesting that medial meniscal release of intact menisci should be considered when performing TTA in dogs.

Subchondral bone changes in three different canine models of osteoarthritis

To test the hypothesis that changes in subchondral bone are significantly different among three canine models of osteoarthritis (OA). In 21 purpose-bred mongrel dogs, OA was induced in one knee joint via either anterior cruciate ligament transection (ACLt; n=5), medial femoral condylar groove creation (GR; n=6), or medial meniscal release (MR; n=5). Five dogs that had sham surgery (SH; n=5) in one knee joint served as controls. Lameness scoring was performed every 4 weeks. Twelve weeks after surgery, the knee joints were examined by histology and histomorphometry. Articular cartilage pathology as determined by Mankin scores was significantly severe in all three OA models compared to SH controls in the medial tibia (P<0.001 to P=0.026). ACLt had significantly thinner subchondral plate thickness (Sp.Th) in both the medial and lateral tibias while MR had significantly thicker Sp.Th in the medial tibia compared to SH controls (P<0.001 to P=0.011). Trabecular bone volume (BV/TV) and trabecular bone thickness (Tb.Th) for ACLt were significantly less than SH controls in the tibias (P<0.001 to P=0.011). Tibial Sp.Th, BV/TV, and Tb.Th were all moderately to strongly correlated with lameness scores obtained throughout the study period (r=-0.436 to r=-0.738, P<0.001 to P=0.047) while Mankin scores showed moderate to strong correlations with Sp.Th in each OA model (r=0.465 to r=0.816, P<0.001 to P=0.033). Changes in Sp.Th are associated with articular cartilage damage while tibial Sp.Th and BV/TV and Tb.Th appear to be all influenced by joint loading alterations.

Retrospective study of 476 tibial plateau levelling osteotomy procedures

To determine the rate of subsequent 'pivot shift', meniscal tear and risk factors associated with complications of tibial plateau levelling osteotomy (TPLO) and to assess clinical and owner perception outcome. Retrospective study. Three hundred and forty-eight dogs that had undergone TPLO surgical procedures (n = 476 stifles). Medical records were reviewed for the retrieval of information on breed, sex, age, body weight, clinical history, radiograph findings, pre- and postoperative tibial plateau angle, limb alignment, unilateral versus bilateral disease, condition of cranial cruciate ligament (CCL) and menisci, implant material, healing time and complications. Clinical and owner-assessed questionnaire outcomes were also recorded. Forty-six (9.7%) postoperative complications were reported. Twenty (4.2%) were classified as major complications requiring an additional surgical intervention, and 26 (5.5%) as minor complications. No risk factors associated with postoperative complications were identified. Ten (2.1%) subsequent meniscal injuries in the stifles with normal un- altered menisci at time of TPLO were reported with a median postoperative time of 9.5 months. Signs of postoperative 'pivot shift' were reported in 15 (3.1%) stifles. All stifles with a 'pivot shift' had a complete CCL rupture or a debrided partial CCL rupture; a medial menisectomy was identified as a risk factor for a 'pivot shift' (p = 0.02). Dogs with intact medial meniscus had a significantly higher activity level (p <0.0001) and a shorter time to peak function (p = 0.02) than dogs that underwent menisectomy according to an owner questionnaire. Dogs with TPLO and intact meniscus seemed to have a better and faster recovery than dogs with TPLO and menisectomy based on owner questionnaires. 'Pivot shift' was infrequent after TPLO surgery. All dogs with a 'pivot shift' had a complete CCL rupture or a debrided partial CCL rupture and menisectomy was identified as a risk factor for its occurrence. Considering the relatively low rate of subsequent meniscal injury after TPLO, systematic medial meniscal release with TPLO may be unnecessary. The 'pivot shift' deserved further investigation to completely understand its mechanism, to identify its anatomic components and potential consequences on the stifle joint.

Meniscal Release in Cruciate Ligament Intact Stifles Causes Lameness and Medial Compartment Cartilage Pathology in Dogs 12 Weeks Postoperatively

To evaluate after 12 weeks the effects of caudal medial meniscal release (MR) in the cranial cruciate ligament-intact canine stifle. Blinded, prospective in vivo study. Purpose-bred hound dogs (n=10). Either MR (n=5) or a sham (SH) surgery (n=5) was performed via arthroscopy. Orthopedic examination and subjective lameness evaluation were performed in each dog preoperatively and at 4, 8, and 12 weeks after surgery. Twelve weeks postoperatively, ultrasonographic, radiographic, and arthroscopic examinations were performed on the operated stifles. Gross pathology of the articular cartilage, cruciate ligaments, and menisci was assessed. India ink staining of the femoral and tibial articular surfaces was performed to determine the percent area of articular cartilage damage. At 8 and 12 weeks after surgery, MR dogs were lamer than SH dogs. At 12 weeks, the degree of radiographic OA was significantly higher in MR stifles than in SH stifles. Gross and sonographic meniscal pathology was more severe in MR stifles compared with SH stifles. MR stifles had significantly more severe articular cartilage pathology compared with SH stifles 12 weeks after surgery; pathology was most severe in the medial compartment. MR alone is associated with articular cartilage loss, further meniscal pathology, degenerative joint disease, and lameness. Subsequent osteoarthritis and dysfunction of the stifle joint should be considered when making clinical decisions regarding MR in dogs.

Pressure distributions on the medial tibial plateau after medial meniscal surgery and tibial plateau levelling osteotomy in dogs

To evaluate the effect of medial meniscal release (MMR) and medial, caudal pole hemimeniscectomy (MCH) on pressure distribution in the cranial cruciate ligament (CCL) deficient canine stifle, and with tibial plateau levelling osteotomy (TPLO). Twelve adult dogs. In experiment one, six pairs of cadaveric canine stifles with an intact CCL were axially loaded with a servo-hydraulic material testing machine and pressure distributions were mapped and quantified using pressure sensitive films. Axial loading of each joint was then repeated following MMR, and again after MCH. In experiment two, six pairs of cadaveric canine stifles with or without TPLO were tested before and after CCL transection, and each MMR and MCH procedure using the same methods of experiment 1. In experiment one, MMR and MCH had significant effects on the pressure distribution resulting in a 2.5-fold increase in the percentage of surface area with pressure higher than 10 MPa. In experiment two, CCL transection resulted in a significant change in pressure distribution only in the stifle without TPLO (P<0.05). Both MMR and MCH resulted in a 1.7-fold increase in the percentage of area with peak pressure in the stifle with TPLO (P<0.05). Meniscal surgery results in a change in pressure distribution and magnitude within the medial compartment of the stifle. Compromised function of the meniscus by either MMR or MCH result in stress concentration which may predispose to osteoarthritis.

Evaluation of three approaches to meniscal release

Three approaches to medial meniscal release (MMR) were compared using 48 canine cadaver stifles. The approaches included a caudomedial arthrotomy approach, a blind stab incision based on anatomic landmarks, and an arthroscopic guided approach. The cranial cruciate ligament was intact in all specimens. The time required to perform the meniscal release and joint capsule closure was recorded, as well as completeness and location of the meniscal transection. Damage to the caudal cruciate ligament, femoral cartilage, and medial collateral ligament were recorded. The mini-arthrotomy was 81% successful in accomplishment of MMR with a 4% rate of iatrogenic damage. The blind technique was 56% successful in the accomplishment of MMR with a 4% rate of iatrogenic damage. The arthroscopic guided approach was 62.5% successful in accomplishment of MMR, with a 10% rate of iatrogenic damage. Accomplishment and iatrogenic damage rates were not significantly different among procedures (p > 0.05). Significantly less time was required to perform the blind technique, and significantly greater time was required to perform the arthroscopic guided technique (p > 0.05). Significant differences were not noted among the procedures regarding the ability to accomplish the meniscal release or damage surrounding structures. None of the evaluated approaches for meniscal release resulted in a complete and accurate meniscal release for over 81% of the time.

Use of biochemical markers of osteoarthritis to investigate the potential disease‐modifying effect of tibial plateau levelling osteotomy

To evaluate the hypothesis that the concentration of the 1/20/5D4 epitope of keratan sulphate, cartilage oligomeric matrix protein and total sulphated glycosaminoglycans in synovial fluids from dogs with cranial cruciate ligament disease would be affected by tibial plateau levelling osteotomy. In addition, to evaluate the hypothesis that medial meniscal release or meniscal injury would alter the expression of these candidate biomarkers. Forty-one dogs with naturally occurring cranial cruciate ligament disease were recruited prospectively. Synovial fluids were collected from the index joint before surgery and six weeks and six months postsurgery. Following tibial plateau levelling osteotomy, synovial fluids were assayed for 1/20/5D4 epitope of keratan sulphate and cartilage oligomeric matrix protein concentration using an inhibition ELISA and for sulphated glycosaminoglycans using a direct dye-binding assay. The sulphated glycosaminoglycans ratio did not change significantly during the study. Medial meniscal injury at entry was associated with lower concentrations of synovial fluid cartilage oligomeric matrix protein (P<0.05, unpaired t test). There was no association between medial meniscal release and the changes in marker concentrations, either from 0 to six weeks or 0 to six months. Tibial plateau levelling osteotomy did not significantly alter the expression of the named candidate biomarkers. These findings reflect the limited nature of the arthrotomy or indicate that tibial plateau levelling osteotomy does not influence the progression of osteoarthritis (OA). From these studies, there is no evidence that tibial plateau levelling osteotomy affects cartilage metabolism.