Treatment of patella baja by a modified Z-plasty
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The purpose of this study was to evaluate the efficiency of a modified Z-plasty for patellar tendon lengthening for the treatment of patella baja. Rather than adapting only two tendon reins according to the conventional Z-plasty method, the modified Z-plasty provides four reins to enable multifold overlapping of the tendon tissue.
Between 2010 and 2012, a modified Z-plasty procedure was performed in four patients suffering from patella baja. Physical examinations and standardized scoring instruments served as the evaluation measures.
The median preoperative CD ratio of 0.53 (range 0.43–0.62) was corrected to 1.03 (range 1–1.06) after a median follow-up of 34 months (range 23–41 months). The median preoperative flexion of 108° (range 80–135°) improved to 143° (range 110–145°) compared with the flexion of 145° (range 140–145°) of the unaffected knee. No patients showed any signs of extension lag. The median Lysholm score improved from 49 (range 22–80) to 91 (range 67–95), and the Tegner activity level improved from 2 (range 0–6) to 6 (range 2–6). The median VAS status for pain decreased from an average of 8.5 (range 4–10) to 1 (range 0–2). No complications were observed.
The modified Z-plasty procedure is a valuable technique for the treatment of patella baja, especially if allografts are not available. This procedure allowed for early mobilization and achieved excellent clinical results.
Level of evidence
KeywordsPatella baja Patella infera Infrapatellar contracture syndrome Patellar tendon lengthening Z-plasty
We thank Caroline Hepperger from the OSM Research Foundation for her highly motivated contribution in collecting the clinical data used for this study.
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