Review Question - QID 219933

TKA Extensor Mechanism Rupture Treatment Operative QID: 219933 (SBQ24HK.50)

QID 219933 (Type "219933" in App Search)

A 68-year-old male returns to the reconstruction clinic 1 year out from left total knee arthroplasty. The patient was doing well at his 2 and 6-week follow-up appointments, however, has not returned to the clinic since. The patient reports approximately 6 months ago he suffered a fall and has had decreased knee extension since that time. Due to concern about contracting a viral illness, he did not want to return to the clinic. An exam of the left lower extremity reveals 110° of knee flexion and a 40° extension lag with palpable patella alta. Plain films of the left knee are shown in Figure A. When comparing extensor mechanism reconstruction with mesh or allograft, which of the following statements is true?

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Mesh reconstruction has a higher reported rate of revision surgery

12%

55/464

Allograft reconstruction has a lower reported mean post-operative extension lag

36/464

Mesh graft reconstruction has a lower monetary cost

66%

306/464

Allograft reconstruction has a higher reported rate of post-operative infection

11%

52/464

Mesh reconstruction has a higher reported use of post-operative walking aid

11/464

Select Answer to see Preferred Response

Extensor mechanism rupture after total knee arthroplasty can be a devastating complication. Recent literature has shown substantial benefits, including lower revision rate and cost, with mesh reconstruction.

Extensor mechanism disruption after total knee arthroplasty is a relatively uncommon complication, with an incidence of 0.17% to 2.5%. However, disruption can lead to knee instability and limited walking ability. Chronic extensor mechanism disruption is treated with reconstruction. Reconstruction options include allograft with bone block or synthetic mesh. Due to the historically high complication rate reported with allograft reconstruction, there is an increased interest in synthetic polypropylene mesh. Mesh reconstruction has been associated with a smaller postoperative extensor lag, lower post-operative use of a walking aid, and decreased graft cost.

Abdel et al report on the results at a single tertiary care institution of 77 patients who underwent extensor mechanism reconstruction with the use of a Marlex mesh. Knee Society Score results and extensor lag significantly improved in the treatment group. The survival rate of the mesh reconstruction was 84%. The authors conclude that although longer follow-up is needed, initial results show excellent functional outcomes.

Wood et al published the results of a multicentric cohort study comparing extensor mechanism reconstruction using either allograft or synthetic graft from 2 high-volume institutions. 27 knees were included, 13 of which underwent synthetic mesh reconstruction and 14 underwent allograft reconstruction. The authors reported a significant decrease in the use of walking aids, mean postoperative extension lag, and graft cost in the synthetic group when compared to the allograft group. The authors conclude that synthetic reconstruction is the preferred option when treating patients with extensor mechanism disruption after total knee arthroplasty.

Figure A shows the AP and lateral plain film of a left total knee arthroplasty with significant patella alta.

Incorrect Answers:
Answer 1: The difference in revision rate between mesh and allograft reconstruction reported in the literature is statistically insignificant.
Answer 2: Allograft has a statistically significant higher mean postoperative extensor lag.
Answer 4: Mesh and allograft have similar reported postoperative infection rates.
Answer 5: Available evidence shows mesh reconstruction has a significantly lower use of postoperative walking aids.