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A comparison between minimally invasive and traditional surgical approaches to total knee arthroplasties in improving functional outcomes and reducing pain levels in adult patients

1 January 2012


Based on the results of the outcomes from Varela et al., Wulker et al., and Tashiro et al., there appears to be insufficient data to strongly support or negate the ability of the MIS TKA approach to reduce pain and improve functional KSS in adults with knee OA who opt for a TKA. Pain and function were measured by validated outcomes (pain medication usage, visual analog pain scale, and Functional KSS ). Varela et al. and Tashiro et al. found clinically significant mean improvements between groups in pain at 24 hours and 1 week after surgery, respectively. We would anticipate that the type and quality of post-surgical pain between 24 hours and 1 week after the operation are different. The time points for assessment of pain were closer for Wulker et al. and Tashiro et al. (8 days and 1 week, respectively); however, in Wulker et al., no clinically significant differences between groups were found. Although we do not know of a reported MCID for the functional KSS, a score of 10 points can move a subject from a subjective category of poor to fair, fair to good, or good to excellent. Thus, mean improvements over 10 points appear to be clinically meaningful. Varela et al. and Tashiro et al. found clinically significant mean improvements in the MIS group in function measured by the Functional KSS, when compared to the Standard TKA group. The time points were closer: Varela et al. looked at KSS at 1 and 3 months post-surgery and Tashiro et al. looked at it at 3 weeks post surgery. Wulker et al. looked at KSS much sooner (8 days post op) and found no difference between the groups. The MIS approaches were also different between the studies. Varela et al. used the subvastus MIS, whereas Wulker et al. and Tashiro et al. used the midvastus MIS. It is possible that the type of MIS approach may have altered the reported outcomes. The internal validity of all three studies was good (PEDro scores ranging from 6-7/10). The external validity was compromised. All 3 studies were completed in foreign countries (Spain, Europe, and Japan) where the average length of hospital stay after a joint replacement surgery far exceeds the average in the USA. Furthermore, Varela et al. and Wulker et al. excluded obese patients, which limits the applicability of the study results to the USA where obesity is prevalent and a contributor to knee osteoarthritis. Further studies must be done in the USA healthcare system in order to determine whether there are earlier post-operative differences in pain or function between the two surgical approaches.
Do minimally invasive surgical approaches to total knee arthroplasties (TKA) result in improved functional outcomes and less pain in patients with degenerative knee osteoarthritis (OA) when compared to a traditional surgical approach?
We are Doctor of Physical Therapy students who are providing physical therapy to patients post-TKA in the acute care setting. We were able to observe both a minimally invasive and a traditional surgical approach. During the immediate post-surgical rehabilitation, we observed that the patient who had undergone the minimally invasive surgery displayed an improved level of function compared to the patient who had undergone the traditional TKA. A variety of health care practitioners we spoke with considered the minimally invasive approach superior to the traditional approach in terms of functional outcomes and pain. We are interested in determining whether the minimally invasive approach is indeed superior to the traditional approach in these regards and believe that this information will help us to prepare more specific plans of care for our future patients post-TKA.


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