Feasibility of feline coxofemoral arthroscopy using a supratrochanteric lateral portal: A cadaveric study.

OBJECTIVE: To evaluate the feasibility of feline diagnostic coxofemoral arthroscopy. STUDY DESIGN: Ex vivo feline cadaveric descriptive study. ANIMALS: Seven feline cadavers (14 hips). METHODS: Gross dissection of two feline hips was performed to evaluate anatomic landmarks, guide arthroscopic portal development, and determine optimal limb positioning. A 1.9 mm, 0° arthroscope, inserted through a supratrochanteric lateral portal, was used to assess intraarticular structures in 12 feline cadaver hips. Arthroscopy was followed by gross dissection of periarticular soft tissues. Relative portal locations and damage to periarticular structures were recorded. Hips were disarticulated, and an India ink assay was performed to assess whether there was iatrogenic cartilage injury (ICI). RESULTS: Scope insertion was achieved in all hips. Articular cartilage of the femoral head and acetabulum, round ligament, joint capsule, transverse acetabular ligament, and dorsal acetabular rim were identified arthroscopically in all hips. Probe insertion and intra-articular structure palpation was achieved in all hips. Scope and instrument portals resulted in minimal periarticular muscle trauma. No sciatic nerve damage was detected. Minor partial thickness ICI was observed in all hips at the site of scope insertion. Focal full thickness ICI was noted in one hip. CONCLUSION: Arthroscopy of the feline coxofemoral joint allowed visual and probe evaluation of intra-articular structures without evidence of major periarticular neurovascular trauma. Iatrogenic cartilage injury occurred in all hips but severity of lesions was considered mild. CLINICAL SIGNIFICANCE: Coxofemoral arthroscopy is feasible in cats and can be utilized as a diagnostic tool for minimally invasive joint evaluation.

Effect of screw insertion angle and speed on the incidence of transcortical fracture development in a canine tibial diaphyseal model.

OBJECTIVE: To assess the incidence of transcortical fracture (TCF) development based on screw insertion angle and screw insertion speed. STUDY DESIGN: Cadaveric experimental study. SAMPLE POPULATION: Sixty-six canine tibiae. METHODS: Sixty-six cadaveric tibiae were randomly assigned to one of six groups that varied based on screw insertion angle relative to the pilot hole (0, 5, or 10°) and screw insertion speed (650 or 1350 revolutions per minute [rpm]). Each tibia was mounted in a custom jig. Locking self-tapping screws (3.5 mm) were inserted at varying speeds and insertion angles, based on group assignment. Orthogonal radiographs were evaluated for TCFs. Fisher's exact tests with a Bonferroni correction were performed to evaluate differences in the frequency of TCF between groups. RESULTS: In Group A (0°/650 rpm: control), a 0% TCF rate was observed (n = 0/80). Group B (5°/650 rpm) had a 3.75% TCF rate (n = 3/80). Group C (10°/650 rpm) had a 12.5% TCF rate (n = 10/80). Group D (10°/hand insertion) had a 3.75% TCF rate (n = 3/80). Group E (10°/1350 rpm) had a 17.5% TCF rate (n = 14/80). Group F (0°/1350 rpm) had a 0% TCF rate (n = 0/80). Groups C and E had the highest TCF rates with a difference in TCF rates observed between the control group and Group C (p = .001) and between the control group and Group E (p < .001). CONCLUSION: Increased screw insertion angle and insertion speed appear to be predisposing factors for TCF development in cadaveric bone. CLINICAL SIGNIFICANCE: Ensuring screw insertion is coaxial with the pilot hole and using slower screw insertion speeds may help reduce the risk of TCF development.

Anatomic structures of the canine middle ear visible during endoscopic examination through a ventral or lateral approach.

OBJECTIVE: To describe the anatomic structures of the canine middle ear visible during endoscopic examination through ventral and lateral surgical approaches. SAMPLE: 5 cadaveric canine heads representing 4 breeds. PROCEDURES: A descriptive study was performed. For each head, a lateral approach was performed on one side and a ventral approach was performed on the opposite side. Images were obtained with a 2.7-mm, 30° telescope. RESULTS: Captured images were reviewed, and anatomic structures visualized through the lateral and ventral approaches were identified. The optimal approach, telescope position, and light post orientation to identify each anatomic structure were subjectively determined. CLINICAL RELEVANCE: Middle ear evaluation with a telescope was technically straightforward and allowed identification of middle ear structures not typically visible with an open surgical approach. Findings may serve as an anatomic reference guide for future video-assisted surgical procedures of the middle ear. A better understanding of the location of anatomic structures in the middle ear may help to prevent unnecessary damage to fragile middle ear structures, such as nerves or blood vessels, during surgical procedures.

Mechanical evaluation of canine sacroiliac joint stabilization using two short screws.

OBJECTIVE: To assess the feasibility and mechanical stability of sacroiliac (SI) joint stabilization using 2 short 3.5 mm cortical screws, each spanning an average of 23% of the width of the sacral body. STUDY DESIGN: Cadaveric experimental study. SAMPLE POPULATION: Twenty-four canine pelvis specimens. METHODS: Pelvis specimens were prepared by disarticulation of the left SI joint and osteotomy of the left pubis and left ischium, and stabilized using a single long lag screw (LLS), 2 short lag screws (SLS) or 2 short positional screws (SPS). Computed tomography (CT) imaging was used to determine standardized screw lengths for each group and was repeated following implant insertion. Specimens were secured within a servohydraulic test frame and loaded through the acetabulum to simulate weight bearing under displacement control at 4 mm/min for 20 mm total displacement. Group mechanical testing data were compared. RESULTS: Peak load, yield load, and stiffness were more than 2 times greater in both the SLS and SPS groups when compared with the LLS group. No mechanical difference was identified between the short-screw groups. CONCLUSION: Sacroiliac luxation fixation using 2 short screws created a stronger, stiffer construct when compared with fixation using a single lag screw spanning 60% of the width of the sacral body. No mechanical advantage was observed between short screws inserted in positional vs. lag fashion. CLINICAL SIGNIFICANCE: Sacroiliac luxation fixation using 2 short screws creates a mechanically superior construct with a larger region of acceptable implant positioning and potentially reduced risk of iatrogenic injury compared with conventional fixation.

Evaluation of a novel method to calculate cementless femoral stem level on craniocaudal projection radiographs.

OBJECTIVE: To assess the accuracy of a proportion-corrected radiographic cementless femoral stem level calculation in a cadaver model. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Twelve cadaveric canine femurs. METHODS: Cementless femoral stems were implanted in 12 cadaver femurs at three stem levels. Craniocaudal projection radiographs of the implanted femurs were obtained at 0°, 10°, 20°, 30°, and 45° angulations in the sagittal plane (relative to the radiographic plate) and at 0°, 15°, and 30° internal and external axial rotation. A proportional calculation including actual stem length, radiographically measured stem length, and radiographically measured stem level relative to the greater trochanter (uncorrected stem level) was solved to yield a corrected stem level. The errors of the stem level measurements were compared. RESULTS: With 0° or 15° of internal rotation, the true stem level differed by more than 0.5 mm from corrected stem level in 2 of 30 tested femoral positions. It differed from the uncorrected stem level in 10 of 30 positions. With 15° and 30° external rotation or 30° internal rotation, the corrected stem level was not more accurate than the uncorrected stem level for any femoral position. CONCLUSION: Use of a proportion correction minimized variability in the stem-level measurements due to sagittal angulation (up to 30°) of the femur at 0° or 15° of internal rotation. CLINICAL SIGNIFICANCE: A proportion correction can improve the accuracy of femoral stem-level assessment on craniocaudal projection radiographs, which may aid in the detection of subsidence after cementless total hip replacement.

Fracture Repair in Cats Using a Conical Coupling Mini 1.9 to 2.5 mm Locking Plate System.

OBJECTIVE: The aim of this study was to retrospectively evaluate the clinical application of the Fixin mini 1.9 to 2.5 system for the treatment of long bone fractures in cats. We proposed that the Fixin mini system would successfully stabilize long bone fractures in cats with a healing time and complication rate similar to those previously reported for feline fractures using other locking bone plate systems. MATERIALS AND METHODS: Medical records and radiographs of cats with long bone fractures stabilized with the Fixin mini 1.9 to 2.5 system were retrospectively reviewed. Signalment, body weight, bone(s) fractured, region of bone fractured, fracture classification, concurrent orthopaedic injuries, complications, time to functional union, if minimally invasive plate osteosynthesis techniques were used, plate size, number of plates, bone graft use and ancillary methods of fixation were recorded. RESULTS: Fifty-six fractures in 54 cats were included. Mean time to radiographic union was 8.8 weeks. Complications were recorded in 8 out of 56 fractures. Major complications occurred in 4 of 56 fractures and minor complications occurred in 4 of 56 fractures. CONCLUSION: The Fixin mini 1.9 to 2.5 system had an overall complication rate and time to functional union similar to that of other implant systems used to treat feline long bone fractures and it appears suitable for repair of a wide variety of long bone fracture configurations in cats.

Evaluation of cementless femoral stem level on mediolateral projection radiographs.

OBJECTIVE: To evaluate the accuracy of measuring cementless femoral stem level on mediolateral projection radiographs. STUDY DESIGN: Benchtop cadaveric. SAMPLE POPULATION: Twelve canine cadaver femurs. METHODS: Cementless femoral stems were inserted into 12 canine cadaver femurs at three levels of subsidence. Mediolateral radiographs were obtained for each femur at 0°, 10°, and - 10° frontal plane angulation and at 0°, 15°, 30°, -15°, and - 30° axial plane rotation. Stem level was measured physically on specimens and on radiographs, and a proportion was used to calculate corrected stem level. Stem level was assessed relative to the greater trochanter and relative to the intertrochanteric fossa. Analysis of variance tests were used to compare actual, radiographically measured, and corrected stem level. RESULTS: No differences were detected between radiographically measured and actual stem level relative to the greater trochanter at 0°, 15°, 30°, and - 30° axial rotation with 0° frontal plane angulation; introduction of 10° or - 10° frontal plane angulation resulted in differences between radiographically measured and actual stem level. Errors >0.5 mm were observed in 82% of radiographic measurements on the basis of the intertrochanteric fossa. The use of a corrective proportion did not improve the accuracy of radiographic measurements. CONCLUSION: Femoral stem level was accurately quantitated on mediolateral projection radiographs in this cadaver model. Frontal plane angulation distorted this measurement. CLINICAL SIGNIFICANCE: Femoral stem subsidence may be assessed on well-positioned mediolateral projection radiographs if the landmarks are visible.

Comparison of femoral stem subsidence between three types of press-fit cementless total hip replacement in dogs.

OBJECTIVE: To compare femoral stem subsidence and determine contributing factors in dogs undergoing total hip replacement (THR) with the traditional BFX, collared BFX, and BFX lateral bolt stems. STUDY DESIGN: Retrospective radiographic study. SAMPLE POPULATION: Ninety-three dogs with 101 THR including dogs undergoing THR with a BFX lateral bolt femoral stem (n = 40), BFX collared stem (n = 21), and traditional BFX stem (n = 40). METHODS: Radiographs of traditional BFX (n = 40), collared BFX (n = 21), and BFX lateral bolt (n = 40) THR performed from 2015 to 2018 were reviewed. Subsidence, canal flare index (CFI), stem canal fill (CF), stem orientation, and complications confirmed on radiographs were recorded at postoperative and recheck radiographs. Analysis of variance tests were used to compare subsidence, CFI, stem orientation, and CF. A χ2 analysis was performed to compare complication rates between groups. RESULTS: Subsidence was lower after placement of BFX lateral bolt stems (median, 0.24 mm; interquartile range [IQR; 1.49) compared with collared (1.27 mm [2.29]) and BFX (1.35 mm [2.26]) stems. No difference in subsidence was detected between collared and BFX implants. Coronal CF was greater after placement of BFX (mean ± SD, 0.72 ± 0.06) compared with lateral bolt (0.69 ± 0.05) or collared (0.66 ± 0.07) stems. Sagittal CF differed between all groups (BFX 0.7 ± 0.05, lateral bolt 0.67 ± 0.06, and collared 0.61 ± 0.06). No differences were identified in CFI or stem orientation in the coronal and sagittal planes or in complication rates between implants. CONCLUSION: The BFX lateral bolt femoral stem was associated with less postoperative subsidence compared with the BFX collared and traditional BFX stems. No consistent changes in CF, CFI, or stem orientation or complication rates were identified in association with increased subsidence in this study. CLINICAL SIGNIFICANCE: Implantation of a lateral bolt femoral stem should be considered during THR to prevent subsidence.

Meniscal click in cranial cruciate deficient stifles as a predictor of specific meniscal pathology.

OBJECTIVE: To determine the predictive value of meniscal click for specific meniscal tear morphology. STUDY DESIGN: Prospective cohort. ANIMALS: Client-owned dogs (104) with cranial cruciate ligament (CCL) deficiency treated with stifle arthroscopy (111). METHODS: All stifles underwent a standardized examination for meniscal click before anesthesia (EBA) and during anesthesia (EDA). Presence or absence of a medial meniscal tear and diagnosis of tear morphology were confirmed with arthroscopic examination. RESULTS: Complete CCL tears were noted in 93 dogs, and incompetent partial tears were noted in 18 dogs. Medial meniscal tears were noted in 40.5% (55/111) of dogs, including bucket handle tears (BHT) in 65.6% (36/55) of tears. Frays of the lateral meniscus were noted in 6.3% of dogs (7/111). Examination for meniscal click before anesthesia was 38% sensitive and 94.5% specific, and EDA was 38% sensitive and 98.2% specific for all meniscal tear morphologies. Positive meniscal click at EBA was associated with a meniscal BHT but not with a meniscal non-BHT (P < .0001 and P = .3515, respectively). Positive meniscal click at EDA was associated with a meniscal BHT but not with a meniscal non-BHT (P < .0001 and P = .1909, respectively). CONCLUSION: A meniscal click is more commonly associated with a meniscal BHT than with a non-BHT. CLINICAL SIGNIFICANCE: Meniscal tear morphology influences the presence or absence of meniscal click. Because of the high incidence of meniscal disease, this study provides evidence to support joint exploration in the treatment of CCL disease.

Percutaneous Plate Arthrodesis.

Arthrodesis is an elective surgical procedure that aims at eliminating pain and dysfunction by promoting deliberate osseous fusion of the involved joint(s). Percutaneous plating can be used to perform carpal and tarsal arthrodeses in dogs and cats. After cartilage debridement is performed, the plate is introduced through separate plate insertion incisions made remote to the arthrodesis site and advanced along an epiperiosteal tunnel, and screws are inserted through the 3 existing skin incisions. The primary advantage of this technique is a decreased risk of soft-tissue complications, including postoperative swelling, ischemia, and wound dehiscence. Preliminary clinical results have been promising.

Percutaneous Pinning for Fracture Repair in Dogs and Cats.

This article describes the technique of percutaneous pinning in dogs and cats. Only acute fractures evaluated within the first 48 hours after trauma are selected for percutaneous pinning. Reduction is performed with careful manipulation of the fracture to minimize the trauma to the growth plate. After ensuring the fracture is reduced anatomically, smooth pins of appropriate size are inserted through stab incisions or through large-gauge needles. Depending on the anatomic location, the pins are cut flush with the bone or bent over. The main advantages of this technique are the minimal surgical trauma and lower perioperative morbidity.

Minimally Invasive Plate Osteosynthesis: Radius and Ulna.

Minimally invasive plate osteosynthesis (MIPO) is a biologically friendly approach to fracture reduction and stabilization that is applicable to many radius and ulna fractures in small animals. An appropriate knowledge of the anatomy of the antebrachium and careful preoperative planning are essential. This article describes the MIPO technique, which entails stabilization of the fractured radius with a bone plate and screws that are applied without performing an extensive open surgical approach. This technique results in good outcomes, including a rapid time to union and return of function.

Correlation of distraction index with arthroscopic findings in juvenile dogs with hip dysplasia.

OBJECTIVE: To compare distraction index (DI) with hip arthroscopy findings in juvenile dogs with hip dysplasia undergoing unilateral or bilateral double pelvic osteotomy (DPO). STUDY DESIGN: Retrospective case series. ANIMALS: Twenty dogs (36 hip joints). METHODS: Medical records from dogs undergoing unilateral or bilateral DPO (2011-2016) were reviewed. Distraction index was measured by using distraction view radiographs. Arthroscopic images were analyzed. Cartilage was graded by using the modified Outerbridge scale (0 = arthroscopically normal, 1 = chondromalacia, 2 = surface fibrillation, 3 = deep fissuring, 4 = full-thickness cartilage loss, and 5 = eburnation of exposed subchondral bone). Dorsal acetabular rim, acetabular labrum, the ligament of head of the femur, and synovitis were graded by using a four-point scale (normal, mild, moderate, severe). Spearman and Pearson correlations were used to compare DI between grade groups and age. RESULTS: Distraction index ranged from 0.4 to 1.0 (mean 0.69 ± 0.16). Most of the hips had an arthroscopically normal femoral head and acetabulum in most regions, except for the region at the insertion of the ligament of the head of the femur. There was a low positive correlation between synovitis and DI (Spearman ρ = 0.35, P = .0346). No other differences in DI were identified between grade or age groups. CONCLUSION: There was a low positive correlation between synovitis and DI. No other differences in DI were identified. CLINICAL SIGNIFICANCE: Arthroscopic evaluation of the coxofemoral joint prior to DPO can allow detection of joint pathology that might not be appreciated by using traditional radiographic screening criteria.

Technique and Outcome of a Modified Tibial Plateau Levelling Osteotomy for Treatment of Concurrent Medial Patellar Luxation and Cranial Cruciate Ligament Rupture in 76 Stifles.

OBJECTIVES: The main aim of this article is to describe the technique and outcome of a modified tibial plateau levelling osteotomy (TPLO) that simultaneously levels the tibial plateau and realigns the quadriceps mechanism through medial translation of the proximal tibial segment in dogs less than 15 kg. MATERIALS AND METHODS: A retrospective medical records search identified dogs with concurrent cranial cruciate ligament rupture (CCLR) and medial patellar luxation (MPL). A study group (76 stifles) treated with a modified TPLO was compared with a non-tibial translation group (45 stifles) corrected with traditional surgical technique. Signalment, arthroscopic findings, adjunctive surgical procedures, osteotomy healing time and complications were recorded. Tibial plateau angle, proximal tibial segment medialization, width of the tibial osteotomy, mechanical medial proximal tibial angle and mechanical medial distal tibial angle were measured and recorded on preoperative and postoperative radiographs. RESULTS: Overall complication rate was 18.4% in the treatment group and 28.9% in the non-tibial translation group. Reluxation occurred in 6.6% of cases in the study group and in 8.8% of cases in the non-tibial translation group. There was no statistical difference in healing time between groups. CLINICAL SIGNIFICANCE: A modified TPLO can be used to treat patients with concurrent MPL and CCLR with good clinical outcome. Complication rates are comparable to traditional repairs for MPL. No major differences were appreciated between study and a non-tibial translation groups for variables compared.

Ex vivo preliminary investigation of radiographic quantitative assessment of cranial tibial displacement at varying degrees of canine stifle flexion with or without an intact cranial cruciate ligament.

BACKGROUND: The presence of cranial tibial subluxation can aid in the detection of joint instability as a result of CrCL injury. Detection of cranial tibial subluxation has been described using the tibial compression test (TCT) and cranial drawer test (CDT); however, diagnosis of CrCL insufficiency by assessing cranial subluxation motion of the tibia is subjective and difficult to quantify accurately. The aim of this study was to investigate a measurement technique to assess the degree of cranial tibial displacement relative to the femoral condyles on mediolateral projection stifle radiographs at varying degrees of stifle flexion (90°, 110°, and 135°) in CrCL intact, partially, and completely transected conditions. Radiographic measurements included: CrCL length and intercondylar distance (ICD), defined as the distance between the tibial mechanical axis (TMA) and the femoral condylar axis (FCA). The influence of CrCL status, stifle flexion angle, and measurement type on measured distance was evaluated. The relationship between CrCL length and ICD measurement was also assessed. RESULTS: Complete transection of the CrCL resulted in significant cranial tibial displacement. Stifle flexion angle affected ICD, but not CrCL length. Normalized measured CrCL length and ICD were significantly different; however, no differences existed between the change in distance detected by CrCL length and ICD measurements as CrCL transection status changed. Correlation coefficients detected a significant positive correlation between measured CrCL and ICD. CONCLUSION: The ICD measurement technique was able to quantify tibial displacement at various stifle flexion angles in the intact and completely transected CrCL conditions. The ICD measurement was more affected by stifle flexion angle than was the CrCL length.

Factors associated with early tibial tuberosity fracture after tibial plateau leveling osteotomy.

OBJECTIVE: To determine factors contributing to tibial tuberosity fracture (TTF) after tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Retrospective case-control study. ANIMALS: Dogs (n = 2490) with cranial cruciate ligament rupture that underwent 3000 TPLO surgeries. METHODS: Radiographs of 3000 stifles from dogs that underwent TPLO were reviewed for evidence of TTF. Two ratios were generated: (1) the height of the tuberosity over the width of the tibia at the most distal extent of the osteotomy (TW) and (2) the width of the narrowest point of the tuberosity over TW. RESULTS: Twenty-three (0.77%) cases of fracture were identified. Factors that correlated with increased odds of fracture were placement of antirotational pins distal to the insertion of the patellar ligament (PL), tuberosities with the narrowest point below the insertion of PL, placement of multiple pins distal to the PL, and bilateral simultaneous TPLO. Tuberosities that fractured were significantly taller and narrower than those that did not fracture. Rotation past the "safe point" and presence of a gap at the osteotomy were not correlated with fracture. CONCLUSION: Placement of multiple pins, pin placement distal to the insertion of the PL, location of the narrowest point of the tibial tuberosity distal to the insertion of the PL, and simultaneous bilateral TPLO were all associated with TTF in this study CLINICAL SIGNIFICANCE: Preoperative planning and postoperative assessment of TPLO should take into consideration the predisposing factors identified in this study to prevent TTF.

Mechanics of Supplemental Drop Wire and Half-Pin Fixation Elements in Single Ring Circular External Fixator Constructs.

OBJECTIVE: Evaluate the effects of supplemental fixation elements on the mechanical properties of a single ring circular fixator construct. STUDY DESIGN: In vitro mechanical testing. SAMPLE POPULATION: Five construct configurations (six replicates of each configuration) were used to stabilize a 1.6 cm diameter Delrin rod bone model. METHODS: Constructs were assembled using 66 mm complete rings, 1.6 mm olive wires, and 3.2 mm diameter half-pins. Construct configurations tested were a base single ring construct, constructs with 1 supplemental drop wire or constructs with 1, 2, or 3 supplemental half-pins. Constructs were loaded in axial compression, caudocranial and mediolateral bending, and torsion. Strain was measured in individual fixation elements during axial loading. RESULTS: A supplemental drop wire or half-pin significantly increased bending and torsional stiffness. The supplemental half-pin increased caudocranial stiffness significantly more than placing a drop wire. Placing a 2nd or 3rd pin afforded significantly greater increases in construct stiffness in all modes of loading, with 3 half-pin constructs having significantly greater axial and caudocranial stiffness than 2 half-pin constructs. Placing a single supplemental pin induced cantilever bending resulting in angular displacement of the Delrin rod during axial loading and high strain in both the fixation wire secured distal to the ring and the pin. Supplemental half-pins incrementally reduced strain in all fixation elements and resulted in linear displacement of the Delrin rod during axial loading. CONCLUSION: If using supplemental half-pins as fixation elements, insertion of 2 or 3 pins is preferred over a single pin.

A biomechanical evaluation of three drop wire configurations.

OBJECTIVE: Evaluate effect of adding drop wires to single-ring constructs. STUDY DESIGN: Biomechanical study SAMPLE POPULATION: Single ring circular external skeletal fixator constructs stabilizing a Delrin segment bone model. METHODS: Eight replicates of 5 constructs made with 66 mm complete rings, 1.6 mm olive wires, and a 15.9-mm diameter Delrin rod were loaded in axial compression, craniocaudal and mediolateral bending, and torsion. Constructs tested were: (1) base single-ring construct; (2) single-ring construct with a drop wire mounted on fixation bolts; (3) single-ring construct with a drop wire mounted on 1-hole posts; (4) single-ring construct with a drop wire mounted on 2-hole posts; and (5) 2-ring construct. Construct stiffness for each mode of loading was compared using repeated measures ANOVAs (P ≤ .05). RESULTS: Axial compression and torsion: the 2-ring construct was stiffer than all others. Drop wire constructs were stiffer than the single-ring construct, but not significantly different from each other. Craniocaudal bending: the 2-ring construct was stiffest with the 2-hole post construct being stiffer than all except the 2-ring construct. Mediolateral bending: the 2-hole post construct was stiffer than the 2-ring construct, which was stiffer than the 1-hole post construct, which was stiffer than the fixation-bolt construct, which was stiffer than the single-ring construct. CONCLUSIONS: Drop wires improved stiffness of single-ring constructs in all loading modalities. Positioning the drop wire farther from the ring surface significantly improved craniocaudal and mediolateral bending stiffness, but did not affect axial compression and torsional stiffness.

Effect of lateral meniscectomy and osteochondral grafting of a lateral femoral condylar defect on contact mechanics: a cadaveric study in dogs.

BACKGROUND: Osteochondral autograft transfer (OAT) aims at restoring normal articular cartilage surface geometry and articular contact mechanics. To date, no studies have evaluated the contact mechanics of the canine stifle following OAT. Additionally, there are no studies that evaluated the role of the meniscus in contact mechanics following OAT in human or canine femorotibial joints. The objective of this study was to measure the changes in femorotibial contact areas (CA), mean contact pressure (MCP) and peak contact pressure (PCP) before and after osteochondral autograft transplantation (OAT) of a simulated lateral femoral condylar cartilage defect with an intact lateral meniscus and following lateral meniscectomy. RESULTS: With an intact lateral meniscus, creation of an osteochondral defect caused a decrease in MCP and PCP by 11% and 30%, respectively, compared to the intact stifle (p < 0.01). With an intact meniscus, implanting an osteochondral graft restored MCP and PCP to 96% (p = 0.56) and 92% (p = 0.41) of the control values. Lateral meniscectomy with grafting decreased CA by 54% and increased PCP by 79% compared to the intact stifle (p < 0.01). CONCLUSIONS: OAT restored contact pressures in stifles with a simulated lateral condylar defect when the meniscus was intact. The lateral meniscus has a significant role in maintaining normal contact pressures in both stifles with a defect or following OAT. Meniscectomy should be avoided when a femoral condylar defect is present and when performing OAT.

Retrospective comparison of minimally invasive plate osteosynthesis and open reduction and internal fixation of radius-ulna fractures in dogs.

OBJECTIVE: To compare the efficacy of reduction, time to union, and clinical outcome of radius and ulna fractures stabilized using either minimally invasive plate osteosynthesis (MIPO) or open reduction and internal fixation (ORIF). STUDY DESIGN: Retrospective, case-controlled study. ANIMALS: Dogs with radius and ulna fractures stabilized with plates applied using MIPO (n = 15) or ORIF (n = 15). METHODS: Dogs in each stabilization group were matched for type and location of fracture, age, and body weight. Outcome measures including surgical time, fracture alignment, gap width, plate length, plate bridging and span ratio, working length and screw density, and time to union were compared between the groups using an unpaired t-test. Statistical significance was set at P < .05. RESULTS: All fractures obtained radiographic union although infection developed in 1 dog in each stabilization group. Dogs treated with MIPO had a significant longer plate working length and lesser screw-density (P < .05). No statistical difference was found in operating time, postoperative alignment, gap width, or time to union (MIPO: 51.9 ± 18.4 days; ORIF: 49.5 ± 26.5 days). CONCLUSIONS: Radius and ulna fractures managed with MIPO had similar alignment, reduction, and time to union as fractures managed with ORIF. Future prospective clinical studies are warranted and should assess healing more frequently and in a standardized manner to compare MIPO to ORIF in a larger population of dogs.