Abstract. Objectives. Stiffness is reported in 4%–16% of patients after having undergone total knee replacement (TKR). Limitation to range of motion (ROM) can limit a patient's ability to undertake activities of daily living with a knee flexion of 83. o. , 93. o. , and 106. o. required to walk up stairs, sit on a chair, and tie one's shoelaces respectively. The treatment of stiffness after TKR remains a challenge. Many treatment options are described for treating the stiff TKR. In addition to physiotherapy the most employed of these is manipulation under anaesthesia (MUA). MUA accounts for up to 36% of readmissions following TKR. Though frequently undertaken the outcomes of MUA remain variable and unpredictable. CPM as an adjuvant therapy to MUA remains the subject of debate. Combining the use of CPM after MUA in theory adds the potential benefits of CPM to those of MUA potentially offering greater improvements in ROM. This paper reports a retrospective study comparing patients who underwent MUA with and without post-operative CPM. Methods. Standard practice in our institution is for patients undergoing MUA for stiff TKR to receive CPM for between 12–24hours post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period several MUA procedures were undertaken without subsequent inpatient CPM. We retrospectively identified two cohorts of patients treated for stiff TKR: group 1) MUA + post-operative CPM 2) Daycase MUA. All patients had undergone initial physiotherapy to try and improve their ROM prior to proceeding to MUA. In addition to patients’ demographics pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded for each patient. Results. In total 168 patients who had undergone MUA between 2017–2022 were identified with a median Age of 66.5 years and 64% female. 57% had extension deficit (>5. o. ), 70% had flexion deficit (< 90. o. ), and 37% had both. 42 had daycase MUA without CPM and the remaining 126 were admitted for post-operative CPM. The mean Pre-operative ROM was 72.3. o. (SD:18.3. o. ) and 68.5. o. (19.0. o. ) for the daycase and CPM groups respectively. The mean ROM recorded at MUA was 95.5. o. (SD:20.7. o. ) and 108.3. o. (SD:14.1. o. ) [p<0.01] and at final follow-up was 87.4o (SD:21.9o) and 92.1o (SD:18.2o) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92% (SD:17%) and 85% (SD:14%) [p=0.03] for daycase and CPM groups respectively. Conclusion. Overall, there was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. Analysis of the percentage ROM gained at MUA maintained at follow up showed that most patients regressed from ROM achieved at MUA in both groups with those in the CPM only maintaining 85% as opposed to 92% in the daycase patients. It is our observation that post-operative CPM does not improve ROM achieved after MUA as compared to MUA alone. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Stiffness is reported in up to 16% of patients after total knee replacement (TKR). 1. Treatment of stiffness after TKR remains a challenge. Manipulation under anaesthesia (MUA) accounts for between 6%-36% of readmissions following TKR. 2,3. The outcomes of MUA remain variable/unpredictable. Post-operative CPM is used as an adjuvant to MUA, potentially offering improved ROM, however, remains the subject of debate. We report a retrospective study comparing MUA with and without post-operative CPM. In our institution patients undergoing MUA to receive CPM post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period MUA procedures were undertaken without CPM. Two cohorts were included: 1) MUA + post-operative CPM 2) Daycase MUA. Patients’ demographics, pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded. Between 2017-2022 126 patients underwent MUA and were admitted for CPM and 42 had daycase MUA. The median Age was 66.5 and 64% were female. 57% had extension deficit (>5. o. ), 70% had flexion deficit (< 90. o. ), and 37% had both. The mean Pre-operative ROM was 72.3. o. (SD:18.3. o. ) vs. 68.5. o. (19.0. o. ), ROM at MUA was 95.5. o. (SD:20.7. o. ) vs 108.3. o. (SD:14.1. o. ) [p< 0.01], and at final follow-up 87.4. o. (SD:21.9. o. ) vs. 92.1. o. (SD:18.2. o. ) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92%(SD:17) and 85%(SD:14)[p=0.03] for daycase and CPM groups respectively. There was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. The CPM group lost a greater ROM after MUA (15% vs. 8%). We conclude that post-operative CPM does not improve ROM achieved after MUA