Derotational osteotomy at the distal femur is effective to treat patients with patellar instability
Bibliographic record
Abstract
PURPOSE: Increased femoral antetorsion influences patellofemoral joint kinematics. The aim of this study was to retrospectively evaluate the clinical outcome after derotational osteotomies and combined procedures in patients with patellofemoral instability. METHODS: All patients with derotational osteotomies and combined procedures in patients with patellofemoral instability and increased femoral antetorsion performed between 2007 and 2016 were retrospectively analyzed. Exclusion criteria were open growth plates, posttraumatic deformities, and a follow-up period less than 12 months. Simple radiography and magnetic resonance imaging to evaluate cartilage lesions, trochlear dysplasia, tubercle distance, and osseous malalignment as frontal axis and torsion were performed on every patient. Patients were evaluated pre- and postoperatively using the visual analog scale (VAS) for pain, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the subjective IKDC evaluation form, the Lysholm score, and the Tegner activity score. RESULTS: Out of 222 femoral osteotomies, a total of 42 patients (44 knees) met the inclusion criteria. Mean preoperative femoral antetorsion of 31° (SD ± 9°) and mean valgus malalignment of 1° (SD ± 3°) were observed. An intended derotation of 12° (SD ± 5°) was set overall. The additional procedures included correction of valgus in 50% (n = 22), MPFL reconstruction in 64% (n = 28), patellofemoral arthroplasty in 18% (n = 8), trochleoplasty in 14% (n = 6), tibial tubercle transfer in 14% (n = 6). During the mean follow-up period of 44 months (SD ± 27, range 12-88), a total of five patients were lost to follow-up, resulting in a follow-up rate of 89% (n = 39). A significant pain relief from VAS 4 (SD ± 3) to VAS 2 (SD ± 2) (p = 0.006) as well as improved scores, WOMAC: from 80 (SD ± 14) to 88 (SD ± 16) (p = 0.007), Lysholm: from 46 (SD ± 21) to 71 (SD ± 24) (p < 0.001), IKDC: from 54 (SD ± 13) to 65 (SD ± 17) (p < 0.001), were observed postoperatively. During the follow-up period, no patellar re-dislocation was observed. CONCLUSION: Combined derotational osteotomy is a suitable treatment for patellar instability due to torsional malformity, as it leads to a significant reduction of pain, and a significant increase of knee function with good-to- excellent results in the short-term follow-up. LEVEL OF EVIDENCE: IV.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".