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Comparable results found with patellar eversion vs retraction during TKA
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BERLIN — The results of a level 1 study with up to 1-year follow-up showed no significant differences in function and pain between patients who underwent total knee arthroplasty with either patellar eversion or lateral retraction.
"Every attempt was made in this study to produce level 1 evidence with our power analysis [and] prospective, randomized, blinded study design," Derek R. Jenkins, MD, of Lenox Hill Hospital, said during his presentation at the 13th EFORT Congress 2012. "[Patients] in each group had similar characteristics and, using these methods, we found no statistically significant detriment to eversion of the patella compared to lateral retraction during total knee arthroplasty based on any of our short-term or long-term objective outcome measures."
Few crossovers
Jenkins and colleagues studied 120 patients with osteoarthritis who had primary total knee arthroplasty performed by three fellowship-trained orthopedic surgeons using a similar operative technique. Patients who had a previous osteotomy or knee arthrotomy were excluded from the study.
Sixty patients were randomized to have their patellas everted during the flexion portion of surgery, and 60 patients had patellar retraction. The groups had similar body mass indexes, ages, and proportions of men and women.
This intraoperative photo shows a sideview of an everted patella.
Images: Jenkins DR
"Three patients who were initially randomized to eversion had body habitus that precluded eversion, so they were laterally retracted. However, our analysis was done on an intention-to-treat basis," Jenkins said.
The investigators found no statistically significant differences between the everted and retracted groups for Visual Analog Scale scores for pain, ambulation and straight leg raise testing at 24 hours, 48 hours and 72 hours postoperatively. In addition, they discovered no significant differences in the length of hospital stays between the groups.
"There was a loss of passive range of motion from preoperatively to 6 weeks in both groups with similar effects," Jenkins said. "Due to our variability and randomization, the preoperative range of motion was greater in the retraction group vs. the eversion group, which persisted to 6 weeks, but then equalized afterwards."
Average quadriceps strength declined from preoperative levels in both groups at 6 weeks, later improved with greater gains seen in the eversion group, equalized and then showed no significant differences between the cohorts at 1 year.
Physical and mental component scores of the SF-36 were not significantly different between the groups at 1 year, Jenkins said.
Complications
The investigators found a greater rate of pulmonary emboli (PE) than reported in the literature, but Jenkins noted that the incidence was unlikely to be related to patellar eversion.
Sixty patients in the study were randomized to patellar retraction, as shown in this photo.
"Recent studies have suggested that because of more sensitive diagnostic modalities, apparent rates of non-fatal PE have increased — this is in agreement with our findings," Jenkins said.
He also noted that all of the patients with PE were treated with routine anti-coagulation, and there were no mortalities.
Two eversion patients had partial minor intraoperative patellar tendon avulsions, but Jenkins reported that these patients did not demonstrate significant inferior straight leg raise, quadriceps strength or other outcome measures.
"These were limited in nature, did not require repair, and all their outcome measures were similar to other patients in the group," he said. – by Jeff Craven
Reference:
- Jenkins DR, Rodriguez J, Ranawat A, et al. A randomized, prospective, controlled study evaluating the effect of patellar eversion on functional outcomes in primary total knee arthroplasty. Paper #12-3713. Presented at the 13th EFORT Congress 2012. May 23-25. Berlin.
For more information:
- Derek R. Jenkins, MD, can be reached at Department of Orthopedic Surgery at Lenox Hill Hospital, 100 East 77th Street, New York, NY; email: jenkins.derek@mayo.edu.
- Disclosure: Jenkins has no relevant financial disclosures.
Perspective
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Peter M. Bonutti, MD, FACS, FAAOS, FAANA
Numerous different surgical techniques that are employed by physicians for exposed bone cuts and implant alignment. Dr. Jenkins’ study does not suggest there were a number of investigators performing the study whom would have had differences in their surgical techniques. The question is, "How many surgeons were performing noneverted exposure, which requires some differences in surgical technique, as a routine vs. surgeons who consistently use an everted approach?" If a surgeon has less experience in a specific approach and this is the first in their learning curve, clearly no subsequent difference will be identified.
In addition, Dr. Ranawat clearly describes how he performs total knee arthroplasties without a tourniquet. He only uses them for a short period of time during the cement process. The use of a tourniquet tightens the quadriceps mechanism and further increases the difficulty of everting the patella and stresses the quadriceps mechanism. A factor for Dr. Ranawat’s results may be that he does not use a tourniquet during the bulk of his procedures, and this makes eversion of the patella easier.
The literature clearly uses a number of studies including McAllister and colleagues, Ranawat and colleagues, and Walter and colleagues. All of these show improved results without everting the patella. One study by Dalury and colleagues found no difference, but this was a bilateral knee study which may not be the best model to identify differences.
We can say surgeons who are accustomed to using the standard medial parapatellar approach with everting the patella and who do not use a tourniquet during the bulk of their procedures may not notice a subsequent difference as Dr. Ranawat’s study suggests. Again, one needs to understand the learning curve, surgeon’s experience and subtle differences in soft tissue management. One needs to understand Dr. Ranawat’s approach. We would agree if a surgeon does not use a tourniquet, eversion of the patella or tibial translation may be less of a factor. The study would have to directly relate to the techniques most surgeons use, which are the use of a tourniquet during the majority of the procedure as four other studies have identified a difference of recovery with patella eversion.
References:
- Arnout N, Victor J, Cleppe H, et al. Avoidance of patellar eversion improves range of motion after total knee replacement: A prospective randomized study. Knee Surgery Sports Traumatology Arthroscopy. 2009;17(10):1206-1210.
- Dalury DF, Mulliken BD, Adams MJ, et al. Early recovery after total knee arthroplasty performed with and without patellar eversion and tibial translation. A prospective randomized study. J Bone Joint Surg Am. 2009;91(6):1339-1343.
- McAllister CM, Stepanian JD. The impact of minimally invasive surgical techniques on early range of motion after primary total knee arthroplasty. J Arthroplasty. 2008;23(1):10-18.
- Walter F, Haynes MB, Markel DC. A randomized prospective study evaluating the effect of patellar eversion on the early functional outcomes in primary total knee arthroplasty. J Arthroplasty. 2007;22(4):509-514.
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