Elsevier

The Knee

Volume 22, Issue 4, September 2015, Pages 321-327
The Knee

Prospective randomised trial comparing unlinked, modular bicompartmental knee arthroplasty and total knee arthroplasty: A five years follow-up

https://doi.org/10.1016/j.knee.2015.04.007Get rights and content

Highlights

  • We compared the results of bicompartmental and total knee arthroplasty at 5 years.

  • We examined clinical and functional outcomes as well as intra-operative blood loss.

  • Blood loss was significantly lower in the bicompartmental knee arthroplasty group.

  • Clinical and functional outcomes were similar in both groups at 5 years post-surgery.

Abstract

Background

A significant proportion of patients with knee osteoarthritis have articular degeneration that is limited to the medial and patellofemoral compartments. The objective of this study was to compare clinical outcomes of unlinked bicompartmental knee arthroplasty (BCA) and total knee arthroplasty (TKA) at 5 years in this subset of patients.

Methods

48 patients were randomised into two groups: unlinked, modular bicompartmental arthroplasty and total knee arthroplasty. Data on demographics and clinical outcomes were collected (Bartlett Knee Score, Oxford Knee Score, Knee Society Score). Data on intra-operative blood loss in both groups were also recorded.

Results

Out of the 48 patients, 26 underwent BCA and 22 had TKA. Both groups shared similar demographic profiles. At five years post surgery, there was significant improvement across all functional scores in both groups. However, there was no significant difference in outcome scores in the BCA group compared to the TKA group. The drop in serum haemoglobin levels postoperatively was 1.55 and 2.30 g/dl for the BCA and TKA groups respectively (p < .001). The total amount of blood loss was 397 and 647 ml respectively (p = .001).

Conclusions

Unlinked, modular BCA results in similar clinical and functional scores as TKA for medial and patellofemoral arthritis in the mid-term. Intra-operative blood loss was significantly lower in the BCA group compared to the TKA group. BCA is a viable option for a select group of young and active patients with the advantage of reduced intra-operative blood loss and equivalent functional outcomes as TKA.

Introduction

Osteoarthritis of the knee is a common disease in our population, whereby the medial, lateral and patellofemoral compartments are involved to varying degrees [1]. A large number of patients with debilitating osteoarthritis of the knee have articular degeneration that is limited to the medial and patellofemoral compartments with a relatively healthy lateral compartment. In addition, a significant subset of these patients has been found to have intact cruciate ligaments [2]. While the current standard of care is still total knee arthroplasty (TKA), there has been increasing interest in bicompartmental knee arthroplasty (BCA) as an alternative treatment option.

BCA can be performed using two philosophically different component designs, either with separate modular unlinked components or with a single monolithic design with a fixed relationship between the patello and tibiofemoral components [3]. The limited success of the bicompartmental prostheses has largely been associated with the monolithic designs, with several studies citing a relatively high incidence of patellofemoral complications and need for revision surgery [4], [5], [6]. This is likely related to challenges in sizing and orienting a linked femoral component, possibly resulting in a constrained articulation and abnormal stress transmission across the knee joint [7], [8], [9]. Conversely, a modular, unlinked trochlear and medial femoral condylar prosthesis allows for independent resurfacing of the medial and patellofemoral compartments. This allows for independent sizing and orientation of the separate components and avoids the problems faced when using the linked prostheses.

BCA provides a minimally invasive alternative to TKA that limits bony resection and spares the anterior and posterior cruciate ligaments, as well as the lateral compartment of the knee. These characteristics are essential to facilitating quicker postoperative recovery and increased stability with better restoration of normal knee kinematics and gait pattern [10], [11]. However, there has been little in the literature comparing the mid-term functional outcomes of patients undergoing BCA and TKA [12].

The purpose of this study is to compare the functional outcomes of patients with advanced osteoarthritis limited to the medial and patellofemoral compartments treated with either a modular, unlinked BCA or TKA and the intra-operative blood loss during BCA and TKA. We hypothesized that due to the bicompartmental prosthesis being inherently tissue conserving and bicruciate-retaining in design, it can better restore knee kinematics and result in a superior functional outcome as opposed to TKA. In addition, we hypothesized that the blood loss during BCA is less due to limited surgical dissection and bone cuts as opposed to TKA.

Section snippets

Materials and methods

This study is a prospective, randomised, clinical trial comparing the functional outcomes and intra-operative blood loss of BCA and TKA in patients with advanced osteoarthritis limited to the medial and patellofemoral joints. Institutional Review Board approval was obtained prior to the commencement of this study in January 2007 (CIRB 2007/152/D). The patients were recruited from our specialist outpatient clinic from October 2007 to January 2009.

Patients diagnosed with primary knee

Results

One hundred and twenty-one patients were assessed for eligibility. Thirty-two patients were excluded based on pre-defined exclusion criteria while 41 patients declined to participate. A total of 48 patients enrolled in the study and were randomised to the BCA (n = 26) and TKA (n = 22) groups. Of the 48 patients randomised, six were lost to follow-up, of which two had passed away and four were not contactable at five years post surgery (Fig. 1).

The patient demographic information study showed no

Discussion

While minimally invasive techniques for total knee arthroplasty are commonly used today, bicompartmental arthroplasty has been advocated as an alternative to TKA for limited arthritis of the knee. It offers tissue sparing advantages including preservation of bone stock, retention of both the cruciate ligaments and restoring kinematics which more closely resemble that of the native knee [22], [23]. It also facilitates limited surgical exposure without having to enter the lateral knee joint.

Acknowledgments

The authors would like to thank the staff of the Orthopaedic Diagnostic Centre, Singapore General Hospital, in particular Ms. Chong Hwei Chi and Mr. William Yeo, for their help in the collation of the data presented.

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