Caleb C. Hudson

Minimally invasive plate osteosynthesis: Applications and techniques in dogs and cats

Bone plating has been used as a method of fracture management for many years. Recently, a trend toward the use of fracture fixation techniques which preserve the local fracture environment, known as biological osteosynthesis, has evolved. This trend has resulted in the development of a less traumatic method of bone plating referred to as minimally invasive plate osteosynthesis (MIPO), or percutaneous plating. During MIPO fracture stabilisation, plates are inserted through short incisions and a communicating epiperiosteal tunnel. Typically, bone plates applied in this fashion have a bridging function. Promising outcomes have been reported in human patients undergoing MIPO fracture stabilisation, and limited reports of the use of this technique in dogs and cats have yielded positive results as well. Careful case selection, pre-operative planning, and appropriate instrumentation are necessary when performing the technique. Rapid time to union, low complication rates and good return to function have been noted in human patients. Additional research is needed to define selection criteria and outline the definitive benefits of MIPO in dogs and cats.

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.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.

Minimally Invasive Plate Osteosynthesis in Small Animals: Radius and Ulna Fractures

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 is 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.

Minimally invasive repair of central tarsal bone luxation in a dog.

OBJECTIVES To describe the use of closed reduction and minimally invasive fixation for treatment of a central tarsal bone luxation in a six-year-old spayed female, mixed breed dog with acute onset non-weight bearing right hindlimb lameness. METHODS Physical examination and tarsal radiographs resulted in a diagnosis of central tarsal bone luxation. Closed reduction and minimally invasive screw stabilization were performed with fluoroscopic guidance. External coaptation for six weeks was followed by a gradual return to full function. RESULTS Follow-up examination at 34 months post-surgery revealed the patient to be fully functional on the surgically repaired limb. Radiographs revealed ankylosis of the intertarsal joints. CLINICAL SIGNIFICANCE Minimally invasive ankle surgery is commonly performed in humans but is uncommon in dogs. Based on the results of this single case, minimally invasive reduction and stabilization of central tarsal bone luxation is feasible.

Percutaneous plate arthrodesis in small animals.

Arthrodesis is an elective surgical procedure designed to eliminate articular pain and dysfunction by deliberate osseous fusion. A percutaneous approach can be used to perform tarsal and carpal arthrodeses in dogs and cats. Intraoperative imaging facilitates cartilage debridement performed with a burr inserted through stab incisions. The plate is introduced through an epiperiosteal tunnel and secured with screws inserted through the skin insertion incisions. Additional screws can be placed through separate stab incisions. The primary advantage of this technique is a decreased risk of soft tissue complications such as plantar necrosis or wound dehiscence. Preliminary clinical results are promising.

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.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

BackgroundOsteochondral 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.ResultsWith 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).ConclusionsOAT 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.

A Biomechanical Comparison of Three Hybrid Linear-Circular External Fixator Constructs

OBJECTIVE To evaluate the stiffness, displacement, ring deformation and bone model motion of 3 configuations of linear-circular hybrid fixator constructs loaded in axial compression, craniocaudal and mediolateral bending, and torsion. STUDY DESIGN Biomechanical evaluation. SAMPLE POPULATION Three hybrid construct configurations with 8 replicates/configuration. METHODS Construct Ia used a single, 84 mm, incomplete ring and 2 tensioned olive wires to stabilize 1 bone segment and a primary hybrid rod with 3 fixation pins to stabilize the other bone segment. Constructs Ia(d) and Ib were similar to Ia with the addition of a secondary diagonal hybrid rod. Construct Ib had a fixation pin inserted orthogonally from the diagonal rod. Constructs were loaded for 10 cycles in each mode of loading using a materials testing machine. Ring deformation was assessed by obtaining serial ring measurements. Bone model motion at the fracture gap as a result of loading was also calculated. RESULTS Axial compression: constructs Ia(d) and Ib were significantly stiffer than construct Ia. Craniocaudal bending: Construct Ib was significantly stiffer than construct Ia. Mediolateral bending: there were no significant differences between constructs. Torsion: Construct Ib was significantly stiffer than constructs Ia and Ia(d) . Permanent ring deformation did not occur. Bone model translational motion decreased in constructs Ia(d) and Ib compared to construct Ia. CONCLUSIONS Addition of a secondary hybrid rod as well as biplanar fixation pin placement improved construct stiffness in several loading modes.

Axial stiffness and ring deformation of complete and incomplete single ring circular external skeletal fixator constructs

OBJECTIVE To compare the axial stiffness, maximum axial displacement, and ring deformation during axial loading of single complete and incomplete circular (ring) external skeletal fixator constructs. SAMPLE 32 groups of single ring constructs (5 constructs/group). PROCEDURES Single ring constructs assembled with 2 divergent 1.6-mm-diameter Kirschner wires were used to stabilize a 60-mm-long segment of 16-mm-diameter acetyl resin rod. Construct variables included ring type (complete or incomplete), ring diameter (50, 66, 84, or 118 mm), and fixation wire tension (0, 30, 60, or 90 kg). Axial loading was performed with a materials testing system. Construct secant stiffness and maximum displacement were calculated from the load-displacement curves generated for each construct. Ring deformation was calculated by comparing ring diameter during and after construct loading to ring diameter prior to testing. RESULTS Complete ring constructs had greater axial stiffness than did the 66-, 84-, and 118-mm-diameter incomplete ring constructs. As fixation wire tension increased, construct stiffness increased in the 66-, 84-, and 118-mm-diameter incomplete ring constructs. Maximum axial displacement decreased with increasing fixation wire tension, and complete ring constructs allowed less displacement than did incomplete ring constructs. Incomplete rings were deformed by wire tensioning and construct loading. CONCLUSIONS AND CLINICAL RELEVANCE Mechanical performance of the 66-, 84-, and 118-mm-diameter incomplete ring constructs improved when wire tension was applied, but these constructs were not as stiff as and allowed greater displacement than did complete ring constructs of comparable diameter. For clinical practice, tensioning the wires placed on 84- and 118-mm-diameter incomplete rings to 60 kg is recommended.

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

BackgroundThe 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.ResultsComplete 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.ConclusionThe 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.