Oxford unicompartmental knee arthroplasty: medial pain and functional outcome in the medium term

Abstract

BackgroundIn our experience results of the Oxford unicompartmental knee replacement have not been as good as had been expected. A common post operative complaint is of persistent medial knee discomfort, it is not clear why this phenomenon occurs and we have attempted to address this in our study.Methods48 patients were retrospectively identified at a mean of 4.5 years (range = 3 to 6 years) following consecutive Oxford medial Unicompartmental Knee arthroplasties for varus anteromedial osteoarthritis. The mean age at implantation was 67 years (range 57-86). Of these 48 patients, 4 had died, 4 had undergone revision of their unicompartmental knee replacements and 2 had been lost to follow up leaving 38 patients with 40 replaced knees available for analysis using the 'new Oxford Knee Score' questionnaire. During assessment patients were asked specifically whether or not they still experienced medial knee discomfort or pain.ResultsThe mean 'Oxford score' was only 32.7 (range = 16 to 48) and 22 of the 40 knees were uncomfortable or painful medially.The accuracy of component positioning was recorded, using standard post operative xrays, by summing the angulation or displacement of each component in two planes from the ideal position (according to the 'Oxford knee system radiographic criteria'). No correlation was demonstrated between the radiographic scores and the 'Oxford scores', or with the presence or absence of medial knee discomfort or pain.ConclusionIn our hands the functional outcome following Oxford Unicompartmental knee replacement was variable, with a high incidence of medial knee discomfort which did not correlate with the postoperative radiographic scores, pre-op arthritis and positioning of the prosthesis.

Medial Abrasion Syndrome: A Neglected Cause of Persistent Pain After Knee Arthroplasty

“…However, persistent postoperative pain (PPOP) has been a common occurrence in about 10-53% of patients after a total knee arthroplasty (TKA) and is associated with reduced health-related quality of life [1]- [5]. Studies regarding unicompartmental knee arthroplasties (UKAs) also reported a high incidence of medial knee discomfort and pain which did not correlate with the postoperative radiographic scores, preoperative arthritis, and the positioning of the prosthesis and might lead to unnecessary revisions [6]- [9]. Many factors may be responsible for a painful knee prosthesis.…”

The twin peg Oxford knee — Medium term survivorship and surgical principles

“…With regards to loosening but also other causes of failure, at least four aspects of surgical technique have been mentioned: malposition of the implants [2], overhanging of components leading to soft tissue irritation [3], impingement leading to pain , and medial collateral ligament damage leading to subluxation or dislocation of the meniscal bearing or to valgus malalignment [1,2]. Studies trying to detect the influence of single surgical factors, such as implant positioning, have not been conclusive [20,21]. We therefore recommend to address all factors simultaneously by preserving the medial collateral ligament, positioning the femoral jig centrally, maintaining congruity of the femoral drill hole and ensuring osteochondral clearance to accommodate hyperextension.…”

Knee health promotion option for knee osteoarthritis: A preliminary report of a concept of multidisciplinary management

“…Patients' satisfaction after knee arthroplasty is variable. High percentages of dissatisfaction considering patients' concerns were reported in both UKA [13] and TKA [14,15]. A comparison study between subjective and objective outcome systems revealed poor correlations, suggesting that the concerns and priorities of patients and surgeons differ [16].…”