Perioperative outcomes of the quadriceps-sparing subvastus approach versus medial parapatellar approach for primary total knee arthroplasty.

Aims & Objectives: The quadriceps-sparing subvastus (SV) approach for total knee arthroplasty (TKA) is theorized to prevent extensor mechanism injury, accelerate recovery and is often compared to the medial parapatellar (MPP) approach. We aimed to compare postoperative outcomes of SV and MPP approaches after TKA in the veteran population.

Materials & Methods: We conducted a retrospective cohort study of all unilateral primary TKAs performed at our institution with an MPP or SV approach between January 1st, 2017 and December 31st, 2020. Information on demographics, and comorbidities were extracted from medical records in addition to length of stay, inpatient morphine milligram equivalents (MMEs), time to ambulate, discharge VAS pain score, outpatient MMEs, emergency room presentation within 30 days, and readmissions within 30 days.

Results: We gathered data from 393 patients undergoing TKA, 352 (89.6 %) patients had an MPP approach and 41 (10.4 %) had an SV approach. When controlling for postoperative protocol, there were no significant differences in complications or measured outcomes between the two approaches. An early ambulation protocol significantly expedited time to ambulate  < 0.001 and outpatient MMEs were significantly lower in patients on a tapered outpatient opioid protocol  < 0.001. There were two extensor mechanism complications with the MPP approach (0.57 %) and none with the SV approach.

Conclusion: There were no significant differences and effect sizes were small for measured outcomes between veterans undergoing TKA with SV and MPP approach when controlling for postoperative protocol. However, the SV approach group was underpowered. Results indicate the success of early ambulation and opioid tapering protocols.