Anterior tibial translation was measured in both knees using the radiological Lachman test and the lateral monopodal stance tests in 281 patients with unilateral anterior cruciate ligament (ACL) rupture. Measurements of translation in the medial compartment were more useful than those in the lateral compartment. Measurement of anterior tibial translation in the medial compartment using the radiological Lachman test showed ACL rupture in 92 % of cases compared with 70% for the lateral monopodal stance test. In normal and in ACL-ruptured knees the monopodal stance test showed that every 10#{176} increase in posterior inclination of the tibial plateau was associated with a 6 mm increase in anterior tibial translation; the radiological Lachman test showed a 3 mm increase for every 10#{176} increase in tibial slope.

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Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

PurposeManufacturers of total knee arthroplasty (TKA) have introduced narrower femurs to improve bone-implant fit. However, few studies have reported the clinical consequences of mediolateral oversizing. Our hypothesis was that component oversizing negatively influences the results after TKA.MethodsOne hundred and twelve prospectively followed patients with 114 consecutive TKA (64 females and 50 males) were retrospectively assessed. The mean age of the patients was 72 years (range, 56 to 85 years). The dimensions of the femur and tibia were measured on a preoperative CT-scan and were compared with those of the implanted TKA. The influence of size variation on the clinical outcomes 1 year after surgery was assessed.ResultsMediolateral overhang was observed in at least one area in 66 % of the femurs (84 % in females and 54 % in males) and 61 % of the tibia (81 % in females and 40 % in males). Twenty-two patients presented no overhang in any area and 16 had overhang in all studied zones. The increase in the Pain and KOOS scores were 43 ± 21 and 36 ± 18 in the patients without overhang and 31 ± 19 and 25 ± 13 in patients with overhang (p = 0.033; p = 0.032). Knee flexion was 127° ± 7 and 121° ± 11, respectively. Regression and latent class analysis showed a significant negative correlation between overall oversizing and overall outcome.ConclusionsThis study confirms that oversizing may lead to worse clinical results in TKA. The clinical consequences are that surgeons should pay attention not to oversize implants during implantation nd that oversizing should be ruled out in case of so called unexplained pain.Level of evidenceIV.Electronic supplementary materialThe online version of this article (doi:10.1007/s00167-013-2443-x) contains supplementary material, which is available to authorized users.

IV.

The identification of these high-risk patients is critical so that a surgeon can provide detailed preoperative education in order to give these patients a realistic expectation of their possible satisfaction following TKA.

Therapeutic study, Level IV.

No abstract