Effects of comorbidities on the outcomes of manipulation under anesthesia for primary stiff shoulder.

BACKGROUND Studies on the effects of manipulation under anesthesia (MUA) for primary stiff shoulder when different comorbidities are present are lacking. Our aim was to assess how comorbidities influence the recovery speed and clinical outcomes after MUA. METHODS Between April 2013 and September 2018, 281 consecutive primary stiff shoulders in the frozen phase treated with MUA were included in this study. We investigated the comorbidities of patients and divided them into the control (n=203), diabetes mellitus (DM) (n=32), hyperlipidemia (n=26), and thyroid disorder (n=20) groups. The range of motion (ROM) and clinical scores for each group before MUA and 1 week, 6 weeks, and 3 months after MUA were comparatively analyzed. We identified the ROM recovery time after MUA and the responsiveness to MUA. Then, subjects were subdivided into early and late recovery groups based on their recovery time and into successful and non-successful MUA groups based on their responsiveness to MUA. RESULTS Significant improvements in ROM and clinical scores at 3 months after MUA were observed in all groups. Significant differences in ROM among the four groups were also observed during follow-up (P<.05). The DM group had significantly lower ROM values, even at 3 months after MUA, compared to the control group. The ROM recovery speed after MUA was slowest in the DM group, followed by the thyroid disorder, hyperlipidemia, and control groups. Most (90.6%) of the DM group experienced late recovery. The proportion of non-successful MUA was higher in the DM and thyroid disorder groups than that in the control and hyperlipidemia groups (P=.004). During follow-up, there were no differences among groups regarding the visual analogue scale, University of California at Los Angeles shoulder, and Constant scores CONCLUSION: The ROM recovery speed and responsiveness to MUA for primary stiff shoulder were poorer for the DM and thyroid disorder groups than for the control group. In particular, compared to any other disease, outcomes were poorer when the comorbidity was DM. If patients have comorbidities, then they should be informed before MUA that the comorbidity could affect the outcomes of treatment.