The active knee extension after extensor mechanism reconstruction using allograft is not influenced by "early mobilization": a systematic review and meta-analysis

Postoperative rehabilitation after extensor mechanism reconstruction (EMR) with allograft following total knee arthroplasty (TKA) is not standardized. This meta-analysis aimed to evaluate the effectiveness of early and late knee mobilization after EMR. The range of motion (ROM) and extensor lag in both groups were also assessed as the secondary endpoint. Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, a systematic review of the literature was performed, including studies dealing with the use of allograft for EMR following TKA. Failure was defined as the persistence of extensor lag > 20°. Coleman Methodology Score and Methodological Index for Non-Randomized Studies (MINORS) score were used to assess the quality of studies included. The failure rate was set as the primary outcome in early (4 weeks) and late (8 weeks) mobilization groups after EMR with allograft. Secondary outcomes were postoperative extensor lag and ROM. Twelve articles (129 knees) were finally selected for this meta-analysis. Late and early knee mobilization was described in five and seven studies, respectively. No difference was noted between both groups' failure rates (11/84 vs. 4/38, respectively; p = 0.69). The mean extensor lag at last follow-up was 9.1° ± 8.6 in the early mobilization group, and 6.5° ± 6.1 in the late mobilization group is not significantly different (p > 0.05). The mean postoperative knee flexion was 107.6° ± 6.5 and 104.8° ± 7 in the early and late mobilization group, respectively. While immobilization after EMR in TKA is mandatory to allow tissue healing, early knee mobilization after four weeks can be recommended with no additional risk of failure and increased extensor lag compared to a late mobilization protocol. IV, therapeutic study. Registration PROSPERO (International Prospective Register of Systematic Reviews): CRD42019141574.