Background: Hereditary multiple osteochondromas (hereditary multiple exostoses, HME) is a rare genetic disease characterized by the development of benign osteocartilaginous tumors that may cause severe limb deformities and early onset osteoarthritis. Total knee arthroplasty (TKA) is the method of choice for the treatment of advanced gonarthrosis, however the surgical management with coexisting severe axial limb deformity remains unclear.Case presentation: 65-year-old man with HME and extra-articular multi-axial limb deformity was admitted to the orthopedic department due to chronic knee pain and limited range of motion caused by secondary osteoarthritis. Regarding to the clinical and radiological examinations, after preoperative planning he was qualified to a one-stage TKA combined with tibial shaft osteotomy (TSO). In a one year follow-up full bone union was confirmed with no signs of implant loosening or prosthesis displacement. Patient was very satisfied, did not report any joint pain and has sufficient range of motion without knee instability.Conclusion: The improvement of mechanical axis during TKA is a crucial factor for achieve operative success and long implant survival. Despite the higher risk of complication rate in comparison to two-stage treatment, one-stage TKA with simultaneous TSO should be a considerable method for patients with osteoarthritis and multiaxial limb deformities. This method can give a good clinical and functional outcomes, however should be performed subsequently to careful preoperative planning and proper patient qualification.

Aims: Total knee arthroplasty in patients with fixed valgus deformity is a demanding procedure. The aim of this study was to compare the clinical results of using the lateral approach [LA] versus the medial approach [MA] in the treatment of fixed valgus knee deformities. Methods: This single-center study compared the results of 143 consecutive patients with fixed valgus deformity (mean 21.55° valgus, mean age 68.2 years) undergoing LA Total Knee Arthroplasty [TKA] to 50 patients (mean 16.58° valgus, mean age 67.2 years) undergoing MA TKA. The mean follow-up period was 5.1 years (2–10 years). Data was collected from operative notes, routine postoperative visits, and radiological findings. Apart from a radiological evaluation, patients were clinically assessed both pre- and postoperatively using the Knee Society Score [KSS]. Descriptive statistics together with the Kolmogorov-Smirnov test, the Student’s t-test for independent samples, and the Mann-Whitney U test were used. The level of significance in this study was α = 0.05. Results: In the LA group, the KSS Knee was significantly higher than in the MA group [85.31 vs. 77.42, respectively, p-value < 0.001]. The difference was also in the KSS total but with no statistical significance [155.17 vs. 149.22, p-value 0.087]. The surgery time in the LA group was shorter than in the MA group [81 vs. 91 min, respectively, p-value—0.002]. The complication rate after surgery was higher in the MA group than in the LA group (14% vs. 9%, respectively). Conclusions: The lateral approach is a good alternative to the standard medial parapatellar approach in the treatment of fixed valgus knee deformities. A higher postoperative KSS Knee, shorter surgery time, and similar complication rate make the lateral approach a valuable option for treating patients with osteoarthritis and fixed valgus knee deformity.