Quadriceps grafts and the return to theatre for a stiff, sore knee

Design

retrospective cohort study, level of evidence 3, with adjustment for confounders and subgroup analysis by sex and graft diameter

Population

5653 primary anterior cruciate ligament reconstructions performed 2015 to 2022, categorised by autograft type

Primary outcome

non-revision reoperation within 2 years, and KOOS-based patient-reported outcomes at 2 years

Effect

reoperation for extension deficit or pain 11.9% (quadriceps) vs 5.5% (hamstring) vs 4.7% (bone-patellar), adjusted odds ratio 1.96 (95% CI 1.44 to 2.67)

The quadriceps tendon autograft has gained ground in anterior cruciate ligament reconstruction on the basis of comparable objective outcomes. This retrospective cohort of 5653 primary reconstructions performed between 2015 and 2022 looked at what those comparisons usually leave out: non-revision reoperations, and whether the patient thought it worked.

Overall reoperation within two years was 19.2% for quadriceps tendon, 8.9% for hamstring and 6.9% for bone-patellar tendon-bone (P<0.001). The difference sits almost entirely in reoperation for extension deficit or pain - 11.9%, 5.5% and 4.7% respectively - and quadriceps grafts remained independently associated with it after adjustment, odds ratio 1.96 (95% CI 1.44 to 2.67). Patient-reported outcomes followed: quadriceps grafts had lower odds of achieving the minimal important change than hamstring (0.56, 0.41 to 0.77) and than bone-patellar tendon-bone (0.48, 0.32 to 0.72), and both quadriceps and bone-patellar grafts had higher odds of treatment failure and lower odds of reaching the patient acceptable symptom state than hamstring. Women had more reoperations for extension deficit or pain than men (7.3% vs 5.5%), and women receiving grafts of 9.5 to 12.0 mm had 72% higher odds of it (1.72, 1.14 to 2.56).

Revision and graft failure were deliberately excluded, so this says nothing about whether the graft holds - it says the road to two years is rougher. The signal about large grafts in women is the most immediately actionable part: a graft sized to a rule of thumb rather than to the knee it is going into is a plausible mechanism for extension loss, and it is a decision made in theatre.

• Counsel patients choosing a quadriceps graft that reoperation for stiffness or pain runs at about one in eight by two years.
• Size the graft to the patient rather than to a target diameter, particularly in women - 9.5 to 12.0 mm carried 72% higher odds of reoperation for extension deficit.
• Track terminal extension explicitly in the first six weeks of rehabilitation; this is the outcome that drove the difference.
• Note that revision and graft failure were excluded - this is not evidence about graft survival.
• Level 3 evidence from a single registry-style cohort; treat it as a strong reason to audit your own reoperation rates by graft type.

The statistics, in plain English

This is a level 3 retrospective cohort, so graft choice was made by surgeons for reasons that are not fully captured and may themselves predict reoperation - surgeons adopting a newer graft may also be earlier on their learning curve with it. Adjustment for measured confounders leaves that possibility open. The patient-reported findings are the more robust half, because minimal important change and patient acceptable symptom state are anchored to what patients say matters rather than to a surgeon's threshold for returning to theatre. The subgroup finding in women with larger grafts comes from a stratified analysis and should be read as hypothesis-generating despite its plausibility.

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