TS8: TIBIAL PLATEAU FRACTURE HEALING MONITORED WITH DIFFERENTIALLY LOADED RADIOSTEREOMETRIC ANALYSIS. PRELIMINARY RESULTS OF A PROSPECTIVE COHORT.

Abstract

Differentially loaded radiostereometric analysis (DLRSA) uses RSA whilst simultaneously applying load to the bones under investigation. This technique allows measurement of interfragmentary translations and rotations under measured weight bearing and joint movement. We have recently introduced this technique to monitor tibial plateau fracture healing. This paper presents our preliminary results.

Twelve patients with a 41 B2, B3, C2, or C3 fracture were followed for a minimum of three months. RSA beads were inserted in the largest osteochondral fragment and the adjacent metaphysis. Knee flexion was restricted to 60° for 6 weeks. After partial weight bearing (20kg) between 2 and 6 weeks, patients progressed to full weight bearing. Follow up included clinical and radiological examinations and patient reported outcome scores (Lysholm, KOOS). DLRSA examinations included RSA radiographs in 60° flexion and under measured weight bearing. Significant interfragmentary displacement was defined as translations greater than 0.5mm and/or rotations greater than 1.5°.

There was no loss to follow-up. Longitudinal RSA follow-up: Follow-up RSA radiographs were compared to postoperative examinations. Osteochondral fragment depression was less than 0.5mm in seven patients and between 2 and 4mm in the remaining five patients. Significant interfragmentary displacement after three months was recorded in three patients. DLRSA flexion results: Under 60° of flexion, translations over 0.5mm were recorded in five patients (one postoperatively; one at 2 weeks; two at 6 weeks; and one postoperatively, at 2 weeks and at 3 months). Rotations over 1.5° were recorded in six patients (one postoperatively; two at 2 weeks; one at 6 weeks; one at 2 weeks, 3 months and 4.5 months; and one postoperatively, at 2 weeks, 3 months and 6 months). DLRSA weight bearing results: Under partial weight bearing at two weeks, two patients recorded significant translations, one involving a significant rotation. Under weight bearing as tolerated, three patients recorded significant translations (one at 6 weeks; and two at 18 weeks) and four patients recorded significant rotations (one at 6 weeks; one at 18 weeks; and two at 12 and 18 weeks). Patient Reported Outcomes: Both the Lysholm and KOOS scores improved between 6 weeks and 3 months. DLRSA provides new insight and perspective in tibial plateau fractures. Some fractures take more than three months to heal. Our current rehabilitation protocol was safe in most patients, however significant interfragmentary displacement was encountered in 17% at the 2 week followup, raising questions about the quality of the initial stability.