Is end-stage lateral osteoarthritic knee always valgus? Mechanical alignment analysis and radiographic severity assessment.

BACKGROUND: We hypothesized that not all persons with end-stage lateral osteoarthritis (OA) have valgus malalignment and that full extension radiographs may underreport radiographic disease severity. The purpose of this study was to examine the demographic and radiographic features of end-stage lateral compartment knee OA. MATERIALS AND METHODS: We retrospectively studied 133 knees in 113 patients who had undergone total knee arthroplasty between June 2008 and August 2010. All patients had predominantly lateral idiopathic compartment OA according to the compartment-specific Kellgren-Lawrence grade (KLG). The mechanical axis angle (MAA), compartment-specific KLG and joint space narrowing (JSN) of the tibiofemoral joint at extension and 30° of knee flexion, tibia vara angle, tibial slope angle, body mass index, age, and sex were surveyed. RESULTS: End-stage lateral compartment knee OA has varus (37.6 %), neutral (22.6 %), and valgus (39.8 %) MAA on both-leg standing hip-knee-ankle radiographs. KLGs at 30° of knee flexion (fKLG) were grades 3 and 4 in all patients. However, for KLGs at full extension (eKLG), 54 % of all patients had grades 3 and 4. The others (46 %) showed grades 1 and 2. We observed significant differences in lateral compartment eKLG/eJSN (2.3/2.3 mm in varus, 2.5/1.9 mm in neutral, 2.9/1.6 mm in valgus, p = 0.01 and 0.03, respectively), tibia vara angle (4.9° in varus, 4.1° in neutral, 3.0° in valgus, p < 0.01), and medial compartment eKLG/eJSN (2.1/3.1 mm in varus, 2.0/3.4 mm in neutral, 1.8/4.3 mm in valgus, p < 0.01 and 0.01, respectively) between MAA groups, except for the tibial slope angle (9.7° in varus, 10.1° in neutral, 9.8° in valgus, p = 0.31). CONCLUSION: Varus alignment was paradoxically shown in approximately one-third of those with end-stage lateral knee OA on both-leg standing hip-knee-ankle radiographs. Films taken in full extension underreported the degree of OA radiographic severity. LEVEL OF EVIDENCE: Level IV, observational study.

Periprosthetic supracondylar femoral fractures following total knee arthroplasty: clinical comparison and related complications of the femur plate system and retrograde-inserted supracondylar nail.

BACKGROUND: The purpose of this study is to analyze the clinical results and related complications of the femur plate system (FP) and the retrograde-inserted supracondylar nail (RISN). MATERIALS AND METHODS: The study included 42 cases of periprosthetic supracondylar femoral fractures (PSF) proximal to posterior stabilized total knee arthroplasty between 2005 and 2009. Twenty-four cases of PSF were treated with the FP, and the other 18 cases were treated with the RISN. This study cohort was divided into subgroups according to the AO classification. We retrospectively compared the clinical results between the FP and RISN group. RESULTS: There were no significant differences between the two groups in terms of time of clinical union (p = 0.649). In the subgroup analysis, the mean operation time was significantly different only in subgroup A1 (p = 0.03). Complications were seen in 29.2 % (7/24) of patients in the FP group and 27.8 % (5/18) in the RISN group. The age during the index TKA and fracture fixation was a significant risk (p = 0.008) factor for complications between the two groups. No significant differences were found in the other factors between the two groups. The p value for operative time (p = 0.223), immobilization period (p = 0.129), ROM (p = 0.573), KSS (p = 0.379), KSS functional scores (p = 0.310) and time to union (p = 0.649). CONCLUSION: Clinical results did not differ according to the treatment methods used. Fixation method and fracture type did not cause an increase in the complication rate, but there was a trend toward higher non-union rates with the FP method and higher re-fracture rate with the RISN method. Noting the fact that only increasing age correlated with an increased complication rate, more careful attention should be paid to elderly patients in terms of both prevention and surgical care. LEVEL OF EVIDENCE: Level III, therapeutic study.