Most unicompartmental knee replacement revisions could be avoided: a radiographic evaluation of revised Oxford knees in the National Joint Registry

Abstract

Purpose The purpose of this study was to understand why the revision rate of unicompartmental knee replacement (UKR) in the National Joint Registry (NJR) is so high. Using radiographs, the appropriateness of patient selection for primary surgery, surgical technique, and indications for revision were determined. In addition, the alignment of the radiographs was assessed. Methods Oxford UKR registered with the NJR between 2006 and 2010 and subsequently revised were identified by the NJR. A blinded review was undertaken of pre-primary, post-primary, and pre-revision anteroposterior and lateral radiographs of a sample of 107 cases from multiple centres. Results The recommended indications were satisfied in 70%, with 29% not demonstrating bone-on-bone arthritis. Major technical errors, likely leading to revision, were seen in 6%. Pre-revision radiographs were malaligned and, therefore, difficult to interpret in 53%. No reason for revision was seen in 67%. Reasons for revision included lateral compartment arthritis (10%), tibial loosening (7%), bearing dislocation (7%), infection (6%), femoral loosening (3%), and peri-prosthetic fracture (2%, one femoral, one tibial). Conclusions Only 20% of the revised UKR were implanted for the recommended indications, using appropriate surgical technique and had a mechanical problem necessitating revision. One-third of primary surgeries were undertaken in patients with early arthritis, which is contraindicated. Two-thirds were presumably revised for unexplained pain, which is not advised as it tends not to help the pain. This study suggests that variable and inappropriate indications for primary and revision surgery are responsible for the high rates of revision seen in registries. Level of evidence III, Therapeutic study.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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

“…First, it is a retrospective study of a consecutive case series and there was not a comparative group. Nevertheless, the signi cant low incidence of PPOP after arthroplasty incorporating elimination of MAP in this series compared to other reports [1]- [9] still provides evidence to our hypothesis that MAS is a cause of PPOP. Second, as this is a case series by a single surgeon who utilized the same surgical technique in every case, we are unable to assess other factors such as the approaches and the extent of fat pad resection which might associated with PPOP after arthroplasty.…”

“…No evidence of loosening or wearing of the prostheses was found by radiographic examinations in all groups. [5], [18] and is also a common postoperative complaint after UKA [6]- [9]. According to the ndings of this study, the elimination of MAP during either TKA or UKA could avoid unknown causes of PPOP during more than 3 years follow-up.…”

“…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 arthroplasty (UKA) 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].…”

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

“…The Knee Society scores and all subscales of KOOS were statistically improved in all groups (Tables 3 and 4). [5], [18] and is also a common post operative complaint after UKA [6]- [9]. According to the ndings of this study, the elimination of MAP during either TKA or UKA could avoid unknown causes of PPOP during more than 3 years follow-up.…”

“…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.…”