Medial unicompartmental knee arthroplasty in the ACL-deficient knee

Abstract

Symptomatic osteoarthritis (OA) of the knee develops often in association with anterior cruciate ligament (ACL) deficiency. Two distinct pathologies should be recognised while considering treatment options in patients with end-stage medial compartment OA and ACL deficiency. Patients with primary ACL deficiency (usually traumatic ACL rupture) can develop secondary OA (typically presenting with symptoms of instability and pain) and these patients are typically young and active. Patients with primary end stage medial compartment OA can develop secondary ACL deficiency (usually degenerate ACL rupture) and these patients tend to be older. Treatment options in either of these patient groups include arthroscopic debridement, reconstruction of the ACL, high tibial osteotomy (HTO) with or without ACL reconstruction, unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). General opinion is that a functionally intact ACL is a fundamental prerequisite to perform a UKA. This is because previous reports showed higher failure rates when ACL was deficient, probably secondary to wear and tibial loosening. Nevertheless in some cases of ACL deficiency with end-stage medial compartment OA, UKA has been performed in isolation and recent papers confirm good short- to mid-term outcome without increased risk of implant failure. Shorter hospital stay, fewer blood transfusions, faster recovery and significantly lower risk of developing major complications like death, myocardial infarction, stroke, deep vein thrombosis (as compared to TKA) make the UKA an attractive option, especially in the older patients. On the other hand, younger patients with higher functional demands are likely to benefit from a simultaneous or staged ACL reconstruction in addition to UKA to regain knee stability. These procedures tend to be technically demanding. The main aim of this review was to provide a synopsis of the existing literature and outline an evidence-based treatment algorithm.

Unicompartmental knee arthroplasty: state of the art

“…The first reports highlighted a higher incidence of complications following UKA surgery in ACL-deficient knees, in terms of tibial loosening and a higher revision rate 51 52. Mancuso et al 53 summarised the evidence in the literature concerning ACL deficiency in UKA surgery; they concluded that combining ACL reconstruction and UKA is the preferred treatment option for patients with ACL deficiency and bone-on-bone medial OA. Simultaneous or staged ACL reconstruction tends to provide superior outcomes, in particular in younger and more active patients.…”

“…Simultaneous or staged ACL reconstruction tends to provide superior outcomes, in particular in younger and more active patients. In the elderly, UKA without ACL reconstruction seems to be a reasonable and attractive option if a fixed-bearing design is used, but careful patient selection is necessary 53. The literature shows no statistical difference between survival rates of UKAs implanted in ACL-deficient and ACL-intact knees 54.…”

ACL-deficient knee and unicompartmental OA: state of the art

“…In their review of the literature, Mancuso et al 66 devised a treatment algorithm based on joint stability, patient age and joint function requested by patients. According to the algorithm, the preferred procedure for young patients with ACL rupture and end-stage medial compartment OA is the combined procedure performed in a single surgical step.…”

“…In their systematic review of the literature, Mancuso et al 66 compared the type and rate of complications after combined UKA and ACL reconstruction surgery versus UKA alone for ACL-deficient knees. A significantly higher failure rate was noted in patients who did not undergo ACL reconstruction as compared with those who received a combined procedure (19/154 vs 4/108).…”

“…Such complications require a revision procedure, and conversion to TKA will be the solution in most cases. Of a total of 108 combined UKA and ACL reconstruction procedures described, only three failures (progression of lateral OA, periprosthetic infection and polyethylene dislocation) and four complications (one lateral meniscal tear, two cases of knee joint stiffness, one loose body) were found, all of which were successfully managed with a reoperation 66. Another temporary complication following UKA in ACL-deficient knees without ACL reconstruction as described by Plancher et al 10 is pes anserinus bursitis which usually occurs a few weeks following surgery resulted from increased pull of hamstrings as a dynamic stabiliser.…”