Treatment of patella baja by a modified Z-plasty.

PURPOSE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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: IV.