ANTERIOR KNEE PAIN AFTER PATELLOFEMORAL JOINT REPLACEMENT: REVISION IS NOT THE ANSWER. A FIVE-YEAR SURVIVORSHIP AND FUNCTIONAL OUTCOMES STUDY
Bibliographic record
Abstract
Patellofemoral joint (PFJ) replacement is a bone-preserving knee surgical technique for the treatment of isolated PFJ arthritis. However, the survivorship of this procedure is inconsistent. This study aimed to evaluate survival rates of PFJ replacement, assess postoperative functional outcomes, and identify predictors and primary modes of failure in a single institution. We retrospectively studied a consecutive cohort of 34 patients (36 knees) who underwent PFJ replacement in our centre. We included all patients who had PFJ replacement for isolated PFJ pathology and complained of specific anterior knee pain. Mean age was 60 (SD 12) years, and mean BMI was 30 (SD 7) kg/m2. There were 25 female patients, and mean follow-up period was 5.2 (3 to 9) years. We used the Oxford Knee Score (OKS) and Short Form 12-item Health Survey version 2 (SF-12v2) as functional outcome measurements. All postoperative immediate X-rays were reviewed and compared with the most recent images. All postoperative complications were registered. We performed Kaplan-Meier curves to analyze survival rates, using conversion to total knee arthroplasty (TKA) as the endpoint. Cox proportional hazards regression analysis was used to evaluate potential risk factors for implant failure. The patient-reported outcome measures showed a mean OKS of 34.87 (SD 9.67), and mean SF-12v2 were 36.98 and 52.60 for physical and mental components, respectively. No radiographic failures were recorded at the latest follow-up. The cumulative survival rate was 83.3% at five years of follow-up, with 6 (16.7%) implant failures. All patients were converted to TKA due to unexplained anterior knee pain that persisted even after revision, except for one patient. All revisions were in patients with the patella resurfaced as part of the initial procedure, and none of the unsurfaced native patella were revised. Cox proportional hazards regression analysis revealed that the patient's age, sex, and previous surgeries had no effect on converting PFJ replacement to TKA. Finally, higher BMI was not associated with implant failure and conversion to TKA. This study has shown that PFJ replacements had an 83% survival rate and good functional outcomes at 5-year follow-up in our institution. The most common cause of failure was ongoing and unexplained anterior knee pain, and we did not find any association between age, sex, previous surgeries, and revision surgery.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".