Ex Vivo Comparison of Three Surgical Techniques to Stabilize Canine Cranial Cruciate Ligament Deficient Stifles

Objective— To quantify and compare canine stifle stability after 3 stabilization techniques. Study Design— Randomized controlled study. Sample Population— Adult canine cadaveric pelvic limbs. Methods— Total craniocaudal (CrCa) tibial translation quantified in stifles with the cranial cruciate ligament (CrCL) intact, transected, and stabilized with 1 of 3 techniques: (1) hamstring graft (HG); (2) modified retinacular imbrication (MRIT); (3) anatometric fascia lata translocation (AFLT). Tibial translation was quantified from radiographs generated during application of cranial and caudal forces to the tibia. After removal of all soft tissues except periarticular ligaments and fixation, CrCa tibial translation, as before, and medial–lateral rotation, via torsional loading, was quantified with an active motion analysis system. Total tibial translation was evaluated for effect of technique and cruciate status using mixed effect linear model with significance considered at P‐value <.05. Results— CrCa translation was not significantly different across stabilization techniques with CrCLs intact, transected, or after stabilization. Poststabilization translation was significantly less than posttransection for all techniques. Compared with the intact CrCL, CrCa translation poststabilization after HG was significantly greater whereas poststabilization after MRIT and AFLT was not significantly different. Tibial rotation exceeded instrumentation limits in 62.5% HG limbs, 20% MRIT limbs, and 60% AFLT limbs. Conclusions— All 3 stifle stabilization techniques confer comparable CrCa translational stability after CrCL disruption with that provided by the MRIT and AFLT techniques comparable to the intact CrCL. Clinical Relevance— The extra‐ and intracapsular techniques evaluated in this study reduced CrCa tibial translation in CrCL deficient stifles to varying amounts.     

Wound Healing: The Role of Platelet-Derived Growth Factor and Transforming Growth Factor Beta

Recent investigation into the mechanisms of wound healing has indicated the interaction of many substances, including several growth factors. The activity of platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF-β), are best defined. Both factors are secreted primarily from the alpha granules of platelets, but also from activated macro-phages and fibroblasts. Investigation implicates the platelet as the initiator of wound healing, secreting PDGF, TGF-β, and other factors that are chemotactic for monocytes, macrophages, and fibroblasts. Although their mode of action and degree of effect are different, both PDGF and TGF-β increase the collagen content and early rate of gain of strength in wounds in normal and compromised tissue. In normal tissue, however, there is no long-term effect on wound outcome. The use of exogenous growth factors offers potential for chemical manipulation of the healing wound, particularly in tissues that are compromised, or where healing is abnormal.     

Descriptive Histomorphometric Ingrowth Analysis of the Zurich Cementless Canine Total Hip Acetabular Component

Objectives— To (1) determine bone contact with the outer surface and ingrowth into the perforated outer shell of the Kyon acetabular component at 2, 6, and 12 months after total hip replacement (THR) and (2) determine correlation between radiographic lucency surrounding the cup–bone interface and bone contact and ingrowth.
Study Design— Experimental study.
Animals— Large breed dogs (n=11) with and without hip dysplasia.
Methods— Force platform gait analysis was performed preoperatively and 2, 6, and 12 months after THR. Curvilinear length of lucency (CLL) was measured on pelvic radiographs. Tissue contact with the outer cup and ingrowth into the cup were determined histomorphometrically at 2, 6, and 12 months.
Results— Peak vertical force and vertical impulse of the treated and control hind limb were not significantly different at any time. Median bone contact with the outer cup surface was 77%, 48%, and 76% at 2, 6, and 12 months, respectively. Median bone ingrowth into the cup perforations was 50%, 20%, and 44% at 2, 6, and 12 months, respectively. Median bone ingrowth to the inner cup surface was minimal at any time. CLL did not correlate with bone ingrowth.
Conclusions— Bone ingrowth into cup perforations occurred in each dog and was already present 2 months after THR, but most of the inner cup space remained vacant.
Clinical Relevance— Radiographic lucency surrounding the cup–bone interface does not allow assessment of bone contact with the outer surface or bone ingrowth into the Kyon cup in dogs without clinical problems.     

Pharmacokinetics of the injectable formulation of methadone hydrochloride administered orally in horses

Methadone hydrochloride is a synthetic μ-opioid receptor agonist with potent analgesic properties. Oral methadone has been successfully used in human medicine and may overcome some limitations of other analgesics in equine species for producing analgesia with minimal adverse effects. However, there are no studies describing the pharmacokinetics (PK) of oral opioids in horses. The aim of this study was to describe the PK of orally administered methadone (0.1, 0.2 and 0.4 mg/kg) and physical effects in 12 healthy adult horses. Serum methadone concentrations were measured by gas chromatography/mass spectrometry at predetermined time points for 24 h, and PK parameters were estimated using a noncompartmental model. Physical effects were observed and recorded by experienced clinicians. No drug toxicity, behavioural or adverse effects were observed in the horses. The disposition of methadone followed first order elimination and a biphasic serum profile with rapid absorption and elimination phases. The PK profile of methadone was characterized by high clearance ( Cl / F ), small volume of distribution (V_d/ F ) and short elimination half-life ( t _1/2). The mean of the estimated t _1/2 (SD) for each dose (0.1, 0.2 and 0.4 mg/kg) was 2.2 (35.6), 1.3 (46.1) and 1.5 (40.8), and the mean for the estimated C _max (SD) was 33.9 (6.7), 127.9 (36.0) and 193.5 (65.8) respectively.