PURPOSE: Retrospective study to analyse the difference between weight-bearing and non-weight-bearing alignment in osteoarthritic knees planned for patient-specific instrumented (PSI) total knee arthroplasty (TKA). The aim of the study is to observe whether a difference in alignment can be linked to arthritis staging or zone mechanical axis. METHODS: Full-leg standing radiographs and non-weight-bearing MRI of the whole leg were compared for hip-knee-ankle (HKA) angle, measured according to Moreland criteria, in seventy osteoarthritic patients. Kellgren-Lawrence (KL) staging and classification according to zone mechanical axis with Kennedy zones was done. RESULTS: A mean preoperative HKA angle on standing radiographs of 176.4° ± 7.2° was measured compared to 176.4° ± 6.9° for the MRI whole-leg HKA angle. A difference of 0°-1° was observed in 54% of patients when comparing the weight-bearing with the non-weight-bearing HKA angle. Twenty-three per cent had a difference of 2° and another 23 % a difference of 3° or more. In female patients, the dynamic load pattern of weight-bearing increases the HKA angle due to convex side soft tissue laxity both in varus and valgus knees. More important differences were observed in the KL stage 3 and 4 patients (P < 0.05) and with a load-bearing axis outside of the articular surface (P < 0.05). CONCLUSION: Surgeons should be aware that there is a difference between weight-bearing and non-weight-bearing alignment in patients with Kellgren-Lawrence 3 and 4 with a load-bearing axis outside of the articular surface (Kennedy 0 or 1 or 5). According to this study, these changes seem related to the amount of articular wear and the load-bearing axis. This is important for the preoperative planning process in PSI-assisted TKA. More concave side ligamentous release or more constraint can be necessary than imagined based on the PSI alignment result. Full-leg standing radiographs should be performed for PSI-assisted TKAs to analyse the position of the load-bearing axis. LEVEL OF EVIDENCE: IV.
PURPOSE: Retrospective study to analyse the difference between weight-bearing and non-weight-bearing alignment in osteoarthritic knees planned for patient-specific instrumented (PSI) total knee arthroplasty (TKA). The aim of the study is to observe whether a difference in alignment can be linked to arthritis staging or zone mechanical axis. METHODS: Full-leg standing radiographs and non-weight-bearing MRI of the whole leg were compared for hip-knee-ankle (HKA) angle, measured according to Moreland criteria, in seventy osteoarthritic patients. Kellgren-Lawrence (KL) staging and classification according to zone mechanical axis with Kennedy zones was done. RESULTS: A mean preoperative HKA angle on standing radiographs of 176.4° ± 7.2° was measured compared to 176.4° ± 6.9° for the MRI whole-leg HKA angle. A difference of 0°-1° was observed in 54% of patients when comparing the weight-bearing with the non-weight-bearing HKA angle. Twenty-three per cent had a difference of 2° and another 23 % a difference of 3° or more. In female patients, the dynamic load pattern of weight-bearing increases the HKA angle due to convex side soft tissue laxity both in varus and valgus knees. More important differences were observed in the KL stage 3 and 4 patients (P < 0.05) and with a load-bearing axis outside of the articular surface (P < 0.05). CONCLUSION: Surgeons should be aware that there is a difference between weight-bearing and non-weight-bearing alignment in patients with Kellgren-Lawrence 3 and 4 with a load-bearing axis outside of the articular surface (Kennedy 0 or 1 or 5). According to this study, these changes seem related to the amount of articular wear and the load-bearing axis. This is important for the preoperative planning process in PSI-assisted TKA. More concave side ligamentous release or more constraint can be necessary than imagined based on the PSI alignment result. Full-leg standing radiographs should be performed for PSI-assisted TKAs to analyse the position of the load-bearing axis. LEVEL OF EVIDENCE: IV.
Authors: Alexandra N Colebatch; Deborah J Hart; Guangju Zhai; F M Williams; Tim D Spector; Nigel K Arden Journal: Knee Date: 2008-09-14 Impact factor: 2.199
Authors: Pieter-Jan T K Vandekerckhove; Nicholas Matlovich; Matthew G Teeter; Steven J MacDonald; James L Howard; Brent A Lanting Journal: Knee Surg Sports Traumatol Arthrosc Date: 2016-02-01 Impact factor: 4.342
Authors: Daphne A L Schoenmakers; Peter Z Feczko; Bert Boonen; Martijn G M Schotanus; Nanne P Kort; Pieter J Emans Journal: Knee Surg Sports Traumatol Arthrosc Date: 2017-07-18 Impact factor: 4.342