Reply to Editorial by Mamarelis et al.

We read with interest the editorial by Mamarelis et al. (1), which evaluated our report entitled “The Effect of Timing of Manipulation Under Anesthesia to Improve Range of Motion and Functional Outcomes Following Total Knee Arthroplasty” (Issa K, Banerjee S, Kester MA, Khanuja HS, Delanois RE, Mont MA. J Bone Joint Surg Am 2014;96:1349-57). We thank the authors for their valuable review, in which they have raised several valid points.

The authors noted that several other studies (2-5) have used a ROM less than 90° as an indication for manipulation under anesthesia (MUA), whereas the present study used a threshold of 110°. Because of this, they state that the total number of patients undergoing MUA in this study may be greater, potentially affecting the final mean gains in ROM. Selecting a cut-off for the ROM appropriate for an MUA is challenging and often left to the discretion of the orthopedist. There are no definitive guidelines for acceptable active knee flexion values at 6 weeks after TKA. However, recent literature has demonstrated that ROM greater than 90° is necessary for undertaking many normal activities of daily living. While a ROM of 10° to 95° may be sufficient for walking and sitting (6,7), activities such as ascending stairs (105°), descending stairs (107°), and picking an object up off the floor (117°) require a greater ROM (8). Thus excluding patients with ROM between 90° and 110° may prevent them from benefitting from the advantages of this procedure. Moreover, greater postoperative knee flexion has been associated with higher levels of perceived patient satisfaction, considering patients with less than 110° of flexion were dissatisfied after TKA (9). Thus, we believe that making 110° of flexion our threshold may be more effective at managing patient dissatisfaction with ROM post-surgery.

In addition, Mamarelis et al. indicated that while the report showed a difference in the distribution of patients between early and late MUA groups with regards to patient age, smoking status, and presence of cardiac disease, it did not mention the nature of the distribution. Our purpose was to only elucidate the difference in the proportions of patients in each cohort who had each disease. Furthermore, these variables, such as presence of cardiac disease and smoking status, are categorical variables, therefore making it unfeasible to determine factors such as normal distribution, which is reserved for continuous data.

The authors are in agreement that undergoing early MUA (<12 weeks) is a reasonable first-line treatment for TKA patients who develop arthrofibrosis. We feel that our study design and results are comparable to existing literature (10,11), but also provide further insight into both clinical and patient reported outcomes following early and late MUAs. The authors also questioned whether gains in ROM were maintained over a period of time. We feel that this was accomplished, given that patients were followed for a mean of 51 months (range, 12–81 months). In certain cases, we did not have a hard end-point to motion, but it still may be worth considering performing a MUA after 12 weeks. However, gains in ROM may only be seen in about 50% of patients with only a mean improvement of 17° compared to those who had an early MUA. It is important that physicians inform patients of these potential outcomes when contemplating this treatment method. Once again, we thank Mamarelis et al. for their excellent and informative review of this topic as well as this report.

Acknowledgements

None.

Footnote

Conflicts of Interest: MA Mont is a consultant for, or has received institutional or research support from the following companies: Sage Products, TissueGene, OnGoing Care Solutions, DJO Global, Microport, Orthosensor, National Institutes of Health, Stryker, Medical Compression Systems, Johnson & Johnson, Pacira Pharmaceuticals, Merz. He is on the editorial/governing board of the American Journal of Orthopedics, Journal of Arthroplasty, Journal of Knee Surgery, and Surgical Technology International. The other authors have no conflicts of interest to declare.

References

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