Effect of the Extent of Release for Knee Balancing on Post-Operative Limb Coronal Alignment After Primary Total Knee Arthroplasty

Abstract

Mohammad M Alzahrani,1 Thomas J Wood,2 Lyndsay E Somerville,3 Steven J MacDonald,3 James L Howard,3 Edward M Vasarhelyi,3 Brent A Lanting3 1Department of Orthopaedic Surgery, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia; 2Division of Orthopaedic Surgery, Department of Surgery, Hamilton Health Sciences, McMaster University, Hamilton, ON, Canada; 3Division of Orthopaedic Surgery, Department of Surgery, London Health Sciences Centre University Campus, University of Western Ontario, London, Ontario N6A 5A5, CanadaCorrespondence: Mohammad M AlzahraniDepartment of Orthopaedic Surgery, College of Medicine, Imam Abdulrahman Bin Faisal University, 2835 King Faisal Road, Dammam 34212, Saudi ArabiaEmail [email protected]: Outcomes and longevity of total knee arthroplasty (TKA) depend mainly on restoring knee function, through precise bony resection and appropriate soft tissue balancing. The current literature lacks evidence regarding the degree of radiographic change after intra-operative knee balancing. The purpose of our study was to assess the degree of change in coronal lower extremity alignment by comparing pre-operative to post-operative full-length radiographs (FLR) after quantifying the degree of intra-operative knee balancing and correlate patient-reported outcomes to the extent of balancing required.Patients and Methods: One hundred and fifty-four patients undergoing primary TKA for varus knee osteoarthritis were included in the study. The performed soft tissue releases and bony adjustments to obtain a balanced TKA intra-operatively were prospectively documented and were grouped into minimal, moderate and extensive release groups. Hip-knee-ankle angle (HKA), anatomical femoral-tibial angle (FTA), condylar hip angle (CH), medial proximal tibial angle (MPTA) and condylar plateau angle (CPA) were measured on full-length radiographs both pre-operatively and post-operatively. Frequencies of the soft tissue releases and bony resections in addition to descriptive statistics of the measured angles on the radiographs were recorded. In addition, patient-reported outcome scores (PROMs) were compared between the grouped patients.Results: Of those that were included in the study, 66 knees (42.9%) required minimal release to adequately balance the knee, while 70 (45.5%) required moderate release and 18 (11.7%) required extensive release. No statistically significant differences were found in change of alignment between the groups for all the measured angles. In addition, no difference in PROMs was seen between the groups both pre- and post-operatively.Conclusion: Although we found no association between post-operative coronal alignment of a TKA and the degree of soft tissue release and bony resection, this likely represents the fact that a balanced TKA is dynamic and not dependent on change of single radiographic parameters. Patient-reported outcomes were not impacted by the extent of releases.Keywords: knee arthroplasty, soft tissue, balancing, alignment, outcomes

Keywords

• knee arthroplasty
• soft tissue
• balancing
• alignment
• outcomes