Review Question - QID 219853

Unicompartmental Knee Replacement Indications Contraindications QID: 219853 (SBQ24HK.30)

QID 219853 (Type "219853" in App Search)

A 58-year-old male presents to the clinic with progressive knee pain over the last two years. He was in a car accident ten years ago and underwent fixation of a medial plateau fracture with subsequent removal or hardware two years later. Injections, physical therapy, and nonsteroidal anti-inflammatory drugs have not provided relief. AP radiograph from today's visit is shown in Figure A. Examination reveals pain along the medial joint line only, grade 1A Lachman, negative McMurray, and a flexion contracture of 15 degrees. Which of the following is a contraindication to unicompartmental knee arthroplasty (UKA) in this patient?

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Untreated ACL deficiency

17%

95/574

Flexion contracture

79%

454/574

History of previous trauma

5/574

Likely lateral meniscal injury

7/574

Age <60 years

7/574

Select Answer to see Preferred Response

The patient has a flexure contracture of 15 degrees, which is a contraindication to unicompartmental knee arthroplasty (UKA).

UKA is a technically demanding surgery but can provide significant improvement in the appropriate patient. UKA offers several advantages over TKA: faster rehabilitation, lower estimated blood loss, lower cost, lower rates of PJI, less invasive; preserved bone stock; faster recovery, fewer medical complications, improved survivorship, and easier conversion to TKA. Several contraindications to UKA include inflammatory arthritis, fixed varus (>10 degrees) or valgus (>5 degrees) deformity, flexion contracture (>5-10 degrees), periarticular disease (multicompartmental arthritis, previous meniscectomy, patellofemoral chondrosis), and is typically not performed in younger, high-demand patients.

Jennings et al. reviewed the indications for UKA and outlined the potential benefits compared to TKA. These include faster recovery, improved kinematics, and better functional outcomes. No differences between fixed- and mobile-bearing implants regarding implant survivorship or patient-reported outcomes were found. The authors conclude that UKA can be a cost-effective alternative to TKA when performed at high-volume centers with advanced surgical techniques.

Lombardi et al. reported their matched cohort of 115 mobile-bearing UKA patients with 115 cruciate-retaining TKA patients. In their series, patients undergoing UKA had better range of motion, shorter hospital stays, and improved Knee Society functional scores. The authors concluded that minimally invasive unicompartmental arthroplasty using a rapid recovery protocol allows patients a faster return to a more functional level than total knee arthroplasty.

Figure A demonstrates medial joint line narrowing with subchondral sclerosis.

Incorrect Answers:
Answer 1: Although the patient has had a previous medial tibial plateau fracture, their exam is not concerning for ACL deficiency.
Answer 2: The patient’s previous trauma may make the surgery more challenging secondary to scar tissue, but it is not a contraindication to UKA.
Answer 4: A lateral meniscal tear is unlikely, given his previous injury and examination without lateral joint line pain and negative McMurray.
Answer 5: Age alone is not a contraindication with modern UKA implants demonstrating excellent survivorship at 15 years.