Introduction

Debate over appropriate alignment in total knee arthroplasty has become a topical subject as technology allows planned alignments that differ from a neutral mechanical axis. These surgical techniques employ patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient [1, 2].

The purpose of this study was to evaluate the correlation between post-operative limb alignment and implant migration in subjects receiving shape match derived kinematic alignment.

Introduction

The dual mobility design concept for acetabular liners is intended to reduce the risk of dislocation and increase range of motion, but the wear pattern of this design is unclear and may have implications in implant fixation. Additionally, the solid back cups do not have the option for supplementary screw fixation, providing an additional smooth articulating surface for the liner to move against. The objective of this study was to assess cup fixation by measuring implant migration. A secondary objective was to evaluate the mobile bearing motion after rotating the hip.

Introduction

Surgical techniques for implant alignment in total knee arthroplasty (TKA) is a expanding field as manufacturers introduce patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient. The resulting planned alignment can vary greatly from a neutral mechanical axis. The purpose of this study was to evaluate the early fixation of components in subjects randomized to receive shape match derived kinematic alignment or conventional alignment using computer navigation. A subset of subjects were evaluated with gait analysis.

Purpose: To describe the technique and outcomes of patients requiring Lateral Gastrocnemius flaps for soft tissue coverage of the lateral side of the knee after sarcoma.

Methods: Four patients with sarcomas on the lateral knee capsule were identified. 1 patient had an Osteosarcoma of the proximal tibia resected, requiring reconstruction. 2 patients had Malignant fibrous hystiocytoma proximal to the lateral knee joint and 1 patient had a leiomyosar-coma who presented after 6 failed local resections. The length of follow up is from 13 months to 5 years, average 3.25 years. There were no graft failures. The average surface area of the resection was 118 cm2. There were two sarcoma recurrences requiring excision and radiation. There was one death due to metastases. The technique involves the releasing the gastroc flap down to the aponeurosis and then the careful dissection of the peroneal nerve with delivery of the muscle up behind the peroneal nerve to the lateral aspect of the knee. The flap is rotated fibrous layer down and the muscle readily accepts a meshed skin graft taken locally, giving this technique the advantage of reconstructing a capsule and creating a superior bed for accepting skin grafts.

Results: Average time to healing was 3.8 weeks. There have been no nerve injuries, no graft loss and all had a function range of motion. The functional results have been very reliable. Using the musculoskeletal tumour society score (MSTS) and the Toronto Extremity Salvage Scoring (TESS) system we had an average MSTS score of 21.5 with a percent of 71.5 and a TESS score of 44.5 for the living patients. These correlate to very good outcomes.

Conclusions: The lateral gastrocs flap has a reputation of being technically complex. Meller et al.(1997) report peroneal nerve injuries in 8 of 27 cases. This institution has no complications with this flap and recommends it for soft tissue defects that extend to the midline on the lateral aspect of the knee joint.

Purpose: To describe our experience with vascularised fibulas used in sarcoma limb salvage surgery using standardized patient outcome measures.

Methods: All vascularised fibulas and osteochondral allografts performed in the Capital District Health authority were assessed. A complete chart review and current functional assessment of the patients using the Toronto Extremity Salvage score (TESS) and the Musculosketal Tumour Society (MSTS) score were performed.

Results: Nineteen patients with 19 tumors were recorded. The tumors range from 11 osteosarcomas, 4 Ewing’s sarcoma, 3 Malignant Fibrous Histiocytoma’s and 1 Chondrosarcoma. Average age was 23. The patient demographics are 75% male, 42% smokers, 86% femoral lesions and 13 % presented with pathological fracture. There were 9 hip fusions, 3 knee fusions, 6 intercalary grafts and one osteochondral graft. There was 21 % mortality with 21% lung mets, 20% local recurrence, 15.7% rates of amputation or infection or and non union. Allograft fracture rates of 10% were noted. Two patients underwent numerous operations (18) due to non-compliance. Rate of surgical failures defined as patients requiring re-operation after 2 years is 21%. Of 19 patients 10 are working, 4 are unable and 4 are deceased and 1 lost to follow up. Average follow up is 9.8 years (range of 4–18). Our functional results include TESS averaging 57.5 with a range of 30–105 and MSTS scores of average of 16.8 with a range of 3–28 and a percent score average of 55.8. The average score on the subjective assessment question was 4 equaling a response of accept it and would do it again. The Halifax outcome and functional data corresponds well with that in the literature.

Conclusions: The biological repair of a combination of large Allografts with Vascularised Fibula’s is an excellent long term solution for construct survival with unrestricted patient activity.