Fifteen Year Minimum Follow Up of Anteromedial Tibial Tubercle Transfer for Patellofemoral Arthrosis

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Isolated patellofemoral (PF) osteoarthritis is common, particularly in women. This study evaluated minimum fifteen year follow-up of anteromedial tibial tubercle transfer (AMZ) for lateral or distal patellar facet arthrosis. Fifteen of 23 patients who underwent AMZ (1996 - 2000) and met the inclusion criteria -- persistent retro-patellar pain without frank PF instability -- returned follow-up questionnaires. At arthroscopy, anatomic location(s) and arthrosis severity was documented, as was degree of lateral mal-tracking. Both factors dictated AMZ orientation. Steeper “vertical” versus more “horizontal-type” osteotomies were performed for distal versus lateral/mal-tracking PF lesions, respectively (Figure 1). Follow-up data included pain, instability and satisfaction. Fifteen women (17 knees) were followed for a mean 17.1 years (15.4 - 18.8). Mean age at surgery was 29.5. Three-fourths had previous surgery. A majority (65%) underwent steep AMZ averaging 13.5mm of anteriorization and 8.4mm of medialization. Thirty-five percent underwent horizontal AMZ with an average anteriorization of 10.7mm and medialization of 13.4mm. Ninety-four percent (16/17) were satisfied and would re-opt for surgery. Eighty two percent reported being active at last follow-up. Nearly half engaged in moderate to high intensity sports. Thirty-five percent engaged in recreational activities while 18% were minimally active. Four of sixteen reported substantial activity-related pain at last follow-up (all grade III arthrosis at surgery). The average pain score [range 0-10] for the remaining 75% was 2.1 (p<0.001); and the majority of these patients demonstrated grade I-II arthrosis. Post-AMZ symptomatic medial patellar subluxation was corrected successfully in two patients. Fifty-nine percent underwent removal of hardware and 41% required additional procedures. There were no cases of post-op PF instability or conversion to knee arthroplasty. AMZ is effective in ameliorating symptoms and facilitating active lifestyles 15-20 years out in select young patients with lateral or distal PF arthrosis. Ninety-four percent were satisfied and would choose the procedure again.