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    Investigating the Role of Direct Repair in Acute Extensor Mechanism Disruption

    Researchers from Rush were surprised to find that outcomes were comparable with direct repair and allograft reconstruction. Dr. P. Maxwell Courtney describes the findings, presented at the AAOS 2018 Annual Meeting.

    Direct repair is as valid as allograft reconstruction in managing total knee arthroplasty (TKA) patients with acute extensor mechanism disruption, with comparable improvements in function and reoperation rates.

    This is the conclusion of researchers from Rush University in Chicago, who retrospectively reviewed outcomes of 126 TKA patients who had undergone either direct repair (n=58; 46%) or allograft reconstruction (n=68; 54%) between 2005 and 2014 at Rush. Mean follow-up was 81.2 months.

    Their findings were presented at the 2018 Annual Meeting of the American Academy of Orthopaedic Surgery in New Orleans.

    Historically, direct repair of the extensor mechanism has led to poor outcomes. The researchers at Rush wanted to know if outcomes were better or worse than with allograft reconstruction.

    “Extensor mechanism injuries are a very difficult problem, for both the patient and the surgeon,” said P. Maxwell Courtney, MD, who was a fellow in adult reconstruction at Rush at the time of the study. He’s now with The Rothman Institute in Philadelphia, Pennsylvania.

    “Any time there’s more than one way to do something, we don’t know that there’s a right way. So, unfortunately, surgeons still argue about what the optimal treatment for extensor mechanism injury is.”

    To determine if there’s answer to this debate, Dr. Courtney and his colleagues extracted the following data from the patient records:

    • Demographics
    • Time from injury
    • Medical comorbidities
    • Range of motion
    • Knee Society Scores
    • Reoperations

    They compared outcomes direct repair versus allograft reconstruction using chi-square analysis and Mann-Whitney U test.

    The direct repair patients had a smaller extensor lag preoperatively (12 vs 32; P<0.001) and postoperatively (3 vs 11; P=0.022). No difference was found, however, in improvement in Knee Society Scores (42.8 vs 39.7; P=0.508). Both groups had high reoperation rates: 26% for the direct repair group and 24% for the allograft reconstruction group (P=0.719). The most common reason for reoperation was infection (20 patients; 16%).

    The researchers also performed multivariate analysis with the direct repair group to determine if there were any independent risk factors for reoperation. They found that patients who underwent patella tendon repair had a higher reoperation rate than patients who underwent either quadriceps tendon repair or patella fixation (53% vs 15% vs 8%, respectively; P=0.006). Patella tendon repair (odds ratio [OR] 12.8; P=0.004) and a Charlson Comorbidity Index of more than 3 (OR 12.3; P=0.019) were associated with a greater risk of reoperations.


    “I think the most interesting thing we found was that there was no difference in outcomes between the allograft reconstruction and the acute repair groups,” Dr. Courtney said. “However, when we looked at subgroup analysis of the acute repair groups, patella tendon repairs did the worst. Patients with a quadriceps tendon rupture actually did reasonably well with an acute repair, but patella tendon ruptures have the worst outcomes, and that was a surprising find.”

    The reason, he thinks, is a compromised vascular supply. “The patella tendon becomes devascularized, not only with the resurfacing of the patella, but also with the medial parapatellar arthrotomy. That does compromise the blood supply to the patella,” he said.

    Dr. Courtney advocates direct repair in the acute period after TKA. “Often, we attempt an acute repair because an allograft reconstruction is a big deal – there’s an increased risk for infection, you’re taking cadaver tissue and removing any native tissue that you have,” he said.

    “You don’t burn any bridges doing an acute repair first and then doing an allograft repair later.”

    The exception, as this research showed, is direct repair for an acute patella tendon rupture, particularly with poor tissue quality. “The surgeon should consider doing the last surgery first – consider doing an extensor mechanism allograft” instead of a direct repair, he said.

    Source

    Courtney PM, Edmiston T, Pflederer CT, Levine BR, Gerlinger TL. Is There Any Role for Direct Repair of Extensor Mechanism Disruption Following Total Knee Arthroplasty? (Paper 143). Presented at the 2018 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 6-10, 2018, New Orleans, Louisiana.

    Disclosures

    The study authors have no disclosures relevant to this article.