Veterinary Surgery

Jeffery, Nicholas D.; Granger, Nicolas

doi: 10.1111/j.1532-950X.2011.00956.xpmid: 23253066

Milgram, Joshua; Milshtein, Tomer; Meiner, Yaron

doi: 10.1111/j.1532-950X.2011.00908.xpmid: 22103275

Objective To evaluate the role of the medial collateral ligament, lateral collateral ligament, and the palmar carpal ligaments in the prevention of hyperextension of the antebrachiocarpal (AC) joint. Study Design In vitro experiment. Animals Cadaveric canine thoracic limbs (n = 12 pair). Methods Thoracic limbs from 12 healthy mixed breed dogs, free of carpal joint pathology, were assigned to 1 of 6 groups, defined by the order in which the ligaments stabilizing the AC joint were cut. The antebrachium, carpus, and proximal metacarpal (MC) bones were stripped of all muscle tissue, preserving the carpal joint capsule. After specimens were prepared for biomechanical testing, the manus was loaded using a system of weights and pulleys to extend the carpus. Extension was measured using a single motion tracking sensor fixed to the MC bones. All specimens were tested with all ligaments intact and after cutting each of the ligaments. Results Cutting each of the ligaments resulted in a significant change in the angle of extension of the carpus when compared with carpal extension with the ligaments intact. Cutting the palmar AC ligaments resulted in a significantly larger change in extension angle than occurred after cutting the medial and lateral collateral ligaments. Conclusion Each of the ligaments tested contribute to the prevention of hyperextension of the AC joint.

Muguet‐Chanoit, Audrey C.; Olby, Natasha J.; Lim, Ji‐Hey; Gallagher, Ryan; Niman, Zachary; Dillard, Stacy; Campbell, James; Early, Peter; Mariani, Christopher L.; Muñana, Karen R.; Freeman, Courtenay; Platt, Simon R.; Kent, Marc; Giovanella, Carley;

Newcomb, Brent; Arble, Jason; Rochat, Mark; Pechman, Robert; Payton, Mark

doi: 10.1111/j.1532-950X.2011.00911.xpmid: 22091972

Objective To compare the sensitivity of computed tomography (CT) and myelography to a reference standard of CT myelography for determining localization of Type I intervertebral disc extrusions in dogs. Study Design Prospective blinded comparative study. Animals Dogs with acute onset myelopathy because of suspected disc extrusions (n = 30). Methods Dogs had CT, myelography, and CT myelography to diagnose disc extrusions. Sensitivity of CT and myelography was compared to CT myelography for lateral, longitudinal, and combined localization. Confidence in the assessment of each imaging study was scored by 3 reviewers. Results Sensitivity of CT for lateral, longitudinal, and combined localization was 94%, 91%, and 81%, respectively, and was 64%, 74%, and 53%, respectively for myelography. Sensitivity of all 3 categories of localization was significantly different between modalities (P < .0001, P = .0031, P < .0001). Significant differences in the sensitivity of lateral and combined localization were found between confidence scores for myelography (P < .0001, P < .0001). Significant differences in the sensitivity of lateral, longitudinal, and combined localization were found between confidence scores for CT (P = .011, P = .013, P = .027). Poor sensitivity was obtained for both modalities except when imaging studies were assigned the highest confidence score. Conclusions CT is a more sensitive imaging technique than myelography for localizing disc extrusions when compared to a reference standard of CT myelography. Both modalities yielded high sensitivity with the highest confidence score and poor sensitivity for all other confidence scores.

Hettlich, Bianca F.; Kerwin, Sharon C.; Levine, Jonathan M.

doi: 10.1111/j.1532-950X.2011.00920.xpmid: 22103469

Objective To report findings and outcomes of dogs with reherniation of nuclear material within 7 days of hemilaminectomy for acute thoracolumbar (TL) intervertebral disk extrusion. Study Design Retrospective case series. Animals Chondrodystrophic dogs (n = 11). Methods Dogs with acute neurologic decline within 1 week of surgical decompression for TL disk extrusion were identified. Advanced imaging was used to document extradural spinal cord compression at the previous surgery site. Ten dogs had a 2nd decompressive surgery to remove extruded nuclear material. Results All dogs had acute neurologic deterioration (average, 2 neurologic grades) 2–7 days after initial hemilaminectomy. Computed tomography (CT; n = 10) or myelography (n = 1) documented extradural spinal cord compression compatible with extruded disk material at the previous hemilaminectomy site. Dogs that had a 2nd surgical decompression improved neurologically within 24 hours and were paraparetic at discharge. The single dog that did not have decompressive surgery did not regain deep nociception during 185‐day follow‐up. Conclusions Early reherniation at the site of previous hemilaminectomy can produce acute deterioration of neurologic function and should be investigated with diagnostic imaging. Repeat decompressive surgery can lead to functional recovery.

Blaser, Andrea; Lang, Johann; Henke, Diana; Doherr, Marcus G.; Adami, Chiara; Forterre, Franck

doi: 10.1111/j.1532-950X.2011.00909.xpmid: 22091905

Objectives To assess influence of durotomy on spinal cord blood flow (SCBF) in chondrodystrophic dogs with thoracolumbar disk extrusion. Study design Prospective cohort study. Animals Chondrodystrophic dogs with thoracolumbar disk extrusion (n = 11). Methods Diagnosis was based on neurologic signs, magnetic resonance imaging (MRI) findings, and surgical confirmation. Regional SCBF was measured 3 times intraoperatively by laser‐Doppler flowmetry: (1) before surgical decompression; (2) immediately after decompression by hemilaminectomy‐durotomy; and (3) after 15 minutes of lesion lavage. A standardized hemilaminectomy and durotomy performed by the same neurosurgeon, was used to minimize factors that could influence measurement readings. Results A significant increase in intraoperative SCBF was found immediately after spinal cord decompression and durotomy in dogs but SCBF returned to previous levels or lower after 15 minutes of lavage. Changes in SCBF were not associated with duration of clinical signs; neurologic status, degree of spinal cord compression, or signal intensity changes as assessed by MRI. Conclusion Durotomy does not increase SCBF in dogs with disk extrusion associated spinal cord compression.

Revés, Núria Vizcaíno; Bürki, Alexander; Ferguson, Stephen; Geissbühler, Urs; Stahl, Christina; Forterre, Frank

doi: 10.1111/j.1532-950X.2011.00912.xpmid: 22092156

Objective To analyze the biomechanical changes induced by partial lateral corpectomy (PLC) and a combination of PLC and hemilaminectomy in a T13‐L3 spinal segment in nonchondrodystrophic dogs. Study Design In vitro biomechanical cadaveric study. Sample Population T13‐L3 spinal segments (n = 10) of nonchondrodystrophic dogs (weighing, 25–38 kg). Methods A computed tomography (CT) scan of each T13‐L3 spinal segment was performed. A loading simulator for flexibility analysis was used to determine the range of motion (ROM) and neutral zone (NZ) during flexion/extension, lateral bending, and axial rotation. A servohydraulic testing machine was used to determine the changes in stiffness during compression, dorsoventral, and lateral shear. All spines were tested intact, after PLC in the left intervertebral space of L1‐L2, and after a combination of PLC and hemilaminectomy. Results Statistically significant increases in ROM and NZ (P < .05) were detected during flexion/extension and lateral bending when PLC was performed. A significant increase in ROM (P < .001) was noted during axial rotation and flexion after PLC and hemilaminectomy. Stiffness decreased significantly during compression and dorsoventral shear after each procedure. Decreased stiffness during lateral shear was only significant after a combination of both procedures. Conclusion PLC might lead to some spinal instability; these changes are enhanced when a hemilaminectomy is added.

Pike, Fred S.; Kumar, M. S. A.; Boudrieau, Randy J.

doi: 10.1111/j.1532-950X.2011.00916.xpmid: 22188100

Objective To (1) describe a surgical distraction technique for C1‐2 cervical fractures/luxations or atlantoaxial (AA) subluxations using the base of the skull (basion of the foramen magnum) and either C2‐3 or C3‐4 for the purchase points of intraoperative axial distraction and (2) report outcome in 13 dogs. Study Design Retrospective case series. Animals Dogs (n = 13). Materials and Methods Medical records (September 1995–December 2005) of dogs with fracture/luxation of the cervical spine, or AA subluxations, were reviewed. Only dogs that had intraoperative linear distraction using the base of the skull as a purchase point for a self‐retaining retractor were included. Signalment, presenting neurologic deficits, fracture location, and concurrent injury were recorded. Both short‐term in‐hospital follow‐up, including healing and any complications, and long‐term telephone follow‐up were obtained. Results Realignment of the spinal vertebrae, reestablishing the normal properties of the spinal canal, was achieved after distraction in all dogs. Screws and small pins incorporated into polymethylmethacrylate cement were used to span the fracture ventrally and achieve rigid internal fixation. Eight dogs had a complete neurologic recovery, 2 dogs had slight residual ataxia, 2 dogs died, and 1 dog was lost to follow‐up. Healing was good (mean, 7.5 weeks) or excellent (mean, 5.1 months) based on in‐hospital follow‐up (mean, 5.1 months). On final telephone follow‐up (mean, 7.7 years), no dogs were reported to have had any associated problems or additional surgery. Conclusions This surgical distraction technique was a reliable, relatively simple method to obtain reduction of fracture/luxations of C1‐2 to re‐align the spinal canal. Mortality in this series appears lower than that previously reported and supports surgical management of these injuries.

Coomer, Alastair R.; Lewis, Daniel D.; Wiedner, Ellen; Isaza, Ramiro; Winter, Matthew D.; Aloisio, Fabio; Pool, Roy

doi: 10.1111/j.1532-950X.2011.00897.xpmid: 22092453

Objective To report stabilization of closed, comminuted distal metaphyseal transverse fractures of the left tibia and fibula in a tiger using a hybrid circular–linear external skeletal fixator. Study Design Clinical report. Animal Juvenile tiger (15 months, 90 kg). Methods From imaging studies, the tiger had comminuted distal metaphyseal transverse fractures of the left tibia and fibula, with mild caudolateral displacement and moderate compression. Multiple fissures extended from the fractures through the distal metaphyses, extending toward, but not involving the distal tibial and fibular physes. A hybrid circular–linear external skeletal fixator was applied by closed reduction, to stabilize the fractures. Results The fractures healed and the fixator was removed 5 weeks after stabilization. Limb length and alignment were similar to the normal contralateral limb at hospital discharge, 8 weeks after surgery. Two weeks later, the tiger had fractures of the right tibia and fibula and was euthanatized. Necropsy confirmed pathologic fractures ascribed to copper deficiency. Conclusion Closed application of the hybrid construct provided sufficient stability to allow this 90 kg tiger's juxta‐articular fractures to heal with minimal complications and without disrupting growth from the adjacent physes.

Medl, Nikola; Guerrero, Tomás G.; Hölzle, Ludwig; Hässig, Michael; Lochbrunner, Sebastian; Montavon, Pierre M.

doi: 10.1111/j.1532-950X.2011.00883.xpmid: 22092096

Objective To (1) determine suction tip (intermittent and continuous mode) contamination rate in orthopedic surgery in dogs and cats; (2) examine the effect of surgical time on contamination; and (3) report bacteria isolated. Study Design Clinical study. Sample Population Clean orthopedic surgeries (n = 50). Methods Surgical procedures were assigned to 1 of 2 groups: (1) continuous (n = 25) or (2) intermittent suction (n = 25). A control suction was operated in each surgery. Samples for aerobic and anaerobic bacteriologic examination were collected from the surgical suction at 0, 20, 60 minutes, and at the end of surgery, and from the control suction at the end of the surgery only. Comparison of continuous and intermittent suction data, and the effect of surgical time on contamination rate were analyzed using a Kaplan‐Meier survival analysis followed by a Cox proportional hazards model. P < .05 was considered significant. Results Aerobic contamination occurred in 22 of 50 surgical procedures and there was no anaerobic growth. There was no significant difference between continuous and intermittent suction mode groups (P = .40). Surgical time did not influence the contamination rate (P = .79). Bacterial cultures mainly revealed coagulase‐negative Staphylococci, however multiresistant bacteria were isolated. Conclusions We failed to find superiority of the intermittent operation mode of the suction tip over the continuous mode. A safe time frame before contamination of the suction tip occurs that could not be defined.