Abstract
PurposeThe aim of this study was to assess the mid-term clinical outcome of the ankle joint after total knee arthroplasty (TKA) in high-grade valgus osteoarthritis.MethodsIn this case–control study, n = 36 patients with a preoperative mechanical tibiofemoral angle (mTFA) ≥ 15° who underwent TKA between December 2002 and December 2012 were included. The control group (mTFA < 15°) of n = 60 patients was created using case matching. Radiological [mechanical tibiofemoral angle (mTFA) and ankle joint orientation to the ground (G-AJLO)] and clinical parameters [Foot Function Index (FFI), Knee Society Score, Forgotten Joint Score, and Range of Motion (ROM)] were analysed. The mean follow-up time was 59 months (IQR [56, 62]).ResultsThe degree of correcting the mTFA by TKA significantly correlated with the postoperative FFI (R = 0.95, p < 0.05), although the knee and ankle joint lines were corrected to neutral orientations. A cut-off value of 16.5° [AUC 0.912 (0.85–0.975 95% CI), sensitivity = 0.8, specificity = 0.895] was calculated, above which the odds ratio (OR) for developing ankle symptoms increased vastly [OR 34.0 (9.10–127.02 95% CI)]. ROM restrictions of the subtalar joint displayed a strong significant correlation with the FFI (R = 0.74, p < 0.05), demonstrating that decreased ROM of the subtalar joint was associated with aggravated outcomes of the ankle joint.ConclusionsIn this study, higher degrees of leg axis correction in TKA were associated with increased postoperative ankle symptoms. When TKA is performed in excessive valgus knee osteoarthritis, surgeons should be aware that this might trigger the onset or progression of ankle symptoms, particularly in cases of a stiff subtalar joint.Level of evidenceIII.
Highlights
An increasing specialisation in total knee arthroplasty (TKA) has led to satisfactory patient-related outcomes after TKA, with increasing survivorship rates of the prostheses [11]
Two-sided t tests applied for normal distribution, two-sided Mann–Whitney U test for non-normal distribution, and Fisher’s exact test for categorical variables mTFA mechanical tibiofemoral angle, G-AJLO ankle joint line orientation to the ground, mLDFA mechanical lateral distal femur angle, LDTA lateral distal tibia angle and specificity = 0.895] (Figs. 3, 4)
Range of Motion (ROM) of the subtalar joint significantly correlated with the degree of operative mTFA correction (R = 0.76, p < 0.001)
Summary
An increasing specialisation in total knee arthroplasty (TKA) has led to satisfactory patient-related outcomes after TKA, with increasing survivorship rates of the prostheses [11]. Albeit the merits of specialisation are undeniable, it is. Clinical experience has shown that patients who presented with excessive valgus osteoarthritis of the knee and underwent TKA frequently complained about ankle symptoms after the operation. Research on the interplay between both joints was primarily centred on radiological changes, but valid clinical data are still missing [12, 15, 22, 31]. The primary aim of this study was to assess the mid-term clinical outcome of the ankle joint after TKA in high-grade valgus osteoarthritis. The hypothesis of this study was that the
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