The effect of preoperative adjustment in planning to account for an elevated joint line convergence angle on the accuracy of periarticular knee osteotomies - a pilot study
ESSKA Academy. Ahsan I. 11/08/19; 284381; epEKA-45 Topic: F2 - Proximal tibial osteotomy (2-plane correction)
Dr. Iyaad Ahsan
Dr. Iyaad Ahsan
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The effect of preoperative adjustment in planning to account for an elevated joint line convergence angle on the accuracy of periarticular knee osteotomies - a pilot study

ePoster - epEKA-45

Topic: HTO

Ahsan I.1, Thakrar R.1, Shearman A.2, Chatoo M.1, Yasen S.K.2
1Lister Hospital NHS Trust, Stevenage, United Kingdom, 2Basingstoke Hospital NHS Trust, Basingstoke, United Kingdom

Background: Periarticular knee osteotomy is a recognised surgical option for the management of unicompartmental knee osteoarthritis. By altering the weight bearing axis, the procedure aims to reduce pain by transferring loads to relatively unaffected compartments of the knee joint. The effectiveness of the surgery is correlated with the degree of correction obtained, but. some studies report accuracy as low as 20% in achieving planned corrections. A potential cause of inaccuracy may be related to laxity of soft tissues surrounding the knee, reflected by the joint line convergence angle (JLCA).
Aim: Pilot study assessing the effect on accuracy of knee osteotomy surgery following preoperative adjustment in planning to account for an elevated JLCA.
Methodology: Multicentre retrospective cohort study of prospectively collected data from a dedicated osteotomy database. Patients were identified who had undergone periarticular osteotomy for unicompartmental knee OA with a raised JLCA >4°on preoperative plan. Using digital templating software, a “phantom” correction was performed and the osteotomy re-planned following adjustment of the JLCA to normal range (0-2°). Long leg alignment X-rays were evaluated to assess the pre and post-operative weightbearing axis.
Results: A total of 7 (5M/2F) patients were identified whom fulfilled the inclusion criteria of having undergone a “phantom” correction on their initial preoperative plan for an elevated JLCA (>4°). 6 patients were treated with a medial open wedge high tibial osteotomy and 1 with a lateral closing wedge distal femoral osteotomy, all for varus OA. Using a 10% acceptable range (AR) for error, in 86 % of cases (6 of 7) the targeted Mikulicz point was achieved. An average adjustment of 2.5mm was made based on an elevated JLCA which would have otherwise correlate to an approximate15% overcorrection in the Mikulicz weight bearing axis.
Conclusion: Outcomes following periarticular knee osteotomy surgery are correlated with the degree of correction achieved. Overcorrection can potentially lead to excess load through the healthy cartilage resulting in accelerated wear and early failure of surgery. This pilot study demonstrates that improved accuracy of surgical correction may be achieved by adjusting the degree of correction to account for an elevated JLCA.
The effect of preoperative adjustment in planning to account for an elevated joint line convergence angle on the accuracy of periarticular knee osteotomies - a pilot study

ePoster - epEKA-45

Topic: HTO

Ahsan I.1, Thakrar R.1, Shearman A.2, Chatoo M.1, Yasen S.K.2
1Lister Hospital NHS Trust, Stevenage, United Kingdom, 2Basingstoke Hospital NHS Trust, Basingstoke, United Kingdom

Background: Periarticular knee osteotomy is a recognised surgical option for the management of unicompartmental knee osteoarthritis. By altering the weight bearing axis, the procedure aims to reduce pain by transferring loads to relatively unaffected compartments of the knee joint. The effectiveness of the surgery is correlated with the degree of correction obtained, but. some studies report accuracy as low as 20% in achieving planned corrections. A potential cause of inaccuracy may be related to laxity of soft tissues surrounding the knee, reflected by the joint line convergence angle (JLCA).
Aim: Pilot study assessing the effect on accuracy of knee osteotomy surgery following preoperative adjustment in planning to account for an elevated JLCA.
Methodology: Multicentre retrospective cohort study of prospectively collected data from a dedicated osteotomy database. Patients were identified who had undergone periarticular osteotomy for unicompartmental knee OA with a raised JLCA >4°on preoperative plan. Using digital templating software, a “phantom” correction was performed and the osteotomy re-planned following adjustment of the JLCA to normal range (0-2°). Long leg alignment X-rays were evaluated to assess the pre and post-operative weightbearing axis.
Results: A total of 7 (5M/2F) patients were identified whom fulfilled the inclusion criteria of having undergone a “phantom” correction on their initial preoperative plan for an elevated JLCA (>4°). 6 patients were treated with a medial open wedge high tibial osteotomy and 1 with a lateral closing wedge distal femoral osteotomy, all for varus OA. Using a 10% acceptable range (AR) for error, in 86 % of cases (6 of 7) the targeted Mikulicz point was achieved. An average adjustment of 2.5mm was made based on an elevated JLCA which would have otherwise correlate to an approximate15% overcorrection in the Mikulicz weight bearing axis.
Conclusion: Outcomes following periarticular knee osteotomy surgery are correlated with the degree of correction achieved. Overcorrection can potentially lead to excess load through the healthy cartilage resulting in accelerated wear and early failure of surgery. This pilot study demonstrates that improved accuracy of surgical correction may be achieved by adjusting the degree of correction to account for an elevated JLCA.
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