Introduction

Computer Assisted Total Knee Arthroplasty (CATKA) has proven benefits of achieving reproducible and accurate component alignment with outcomes comparable to conventional jig based TKR. Optical trackers are required for assessment of alignment and are fixed via bone pins. This technique does present its own unique complications including fracture and infection at the pin- sites. We report our experience of a single surgeon series performing CATKA.

Introduction

Computer assisted total knee replacement (CATKR) has been shown to give reproducible and accurate alignment of the mechanical axis. The benefits of the reproducible technique has been demonstrated in literature but there is little evidence of benefits in training junior surgeons in a clinical setting. We show our experience of CATKR performed by junior staff under supervision by the senior author, looking at component alignment and patient reported outcome measures.

Introduction

Minimally invasive Computer Assisted Total Knee Arthroplasty (MICATKA) has benefits of reduced blood loss, shorter hospital stay, improved post-operative quadriceps function and enhanced post-operative recovery. Our study looked into these factors to compare if there was a significant difference when compared to conventional Computer Assisted Total Knee Arthroplasty (CATKA).

Introduction

Unicondylar knee replacement (UKR) surgery is proven long term results in its benefit in medial compartment OA. However, its results are sensitive to component alignment with poor alignment leading to early failure. The advent of computer navigation has resulted in improved mechanical alignment, but little has been published on the outcomes of navigated UKR surgery. We present the results of 253 consecutive Computer Assisted UKR's performed by a single surgeon.

Minimally invasive total knee arthroplasty is growing in popularity. It appears to reduce blood loss, reduce hospital stay, improve post-operative quadriceps function and shorten post-operative recovery. We show our experience of minimally invasive TKA with a computer navigation system.

The first series compared forty MICA TKA and forty conventional computer assisted total knee arthroplasties (CATKA). Component positioning was assessed radiographically with long leg Maquet views. Knee Society Scores (KSS) were recorded pre-operatively and at 6, 12, 18 months. Length of stay and recovery of straight leg raise was also recorded. A second series of fifty MICATKA patients were assessed post-operatively for component alignment using long leg Maquet views. Twenty-two of these patients had assessment of femoral rotation using CT.

In the first series pre-operative KSS showed no significant difference between the two groups. Post-operatively the mean femoral component alignment was 89.7 degrees for MICATKA and 90.2 for CATKA. The mean tibial component alignment was 89.7 degrees for both. KSS at 6, 12, 18 months were statistically better in the MICATKA (p<000.1). Straight leg raise was achieved by day one in 93% of the MICATKA compared to 30% of the CATKA. Length of stay for MICATKA was a mean of 3.25 days with CATKA a mean of 6 days. In the second series the mean femoral component varus/valgus angle was 89.98 degrees, the mean tibial component varus/valgus angle was 89.91 degrees and the mean femoral component rotation was 0.6 degrees of external rotation.

MICATKA is a safe procedure with reproducible results. Alignment is equivalent to CATKA. It gives statistically significant improvement in KSS compared to the open procedure. The length of stay and time to straight leg raise are also reduced. At 2 years follow-up we have seen no revisions and no evidence of loosening radiographically.

The presence of retained metalwork, previou fractures or osteotomies makes TKA surgery challenging. Obstructed intramedually canals can produce difficulty with the use of IM instrumentation whilst the altered alignment can result in problematic soft tissue balancing.

We present a series of 35 patients with deformity who underwent a successful TKA.

Between July 2003 and January 2006 35 patients were operated on between 3 centres. All had extraarticular deformities in either the femur or tibia due to previous fractures or exposure to surgery. All underwent TKA surgery using an image free computer navigation system and extramedullary TKA instrumentation. All patients underwent pre-op and post-operative long eg alignment films.

The pre-operative long eg films showed an alignment of 16 degrees varus to 18 degrees of valgus. Post-operative alignment ranged from 3 degrees varus to 4 degrees valgus. The femoral component position ranged from 88-91 degrees from the mechanical axis whilst the tibial component position ranged from 89-92 degrees from the mechanical axis of the limb.

Total knee arthroplasty in the presence of extraarticular deformity is fraught with problems in regaining limb alignment and soft tissue balancing. This is the largest combined series of patients in which the same navigation system has been used to provide extramedullary alignment and cuts resulting in excellent component positioning and post-operative alignment. We recommend the routine use of computer navigation in these difficult cases.