Postoperative Hip-knee-ankle Angle Research Articles

Impact of knee varus and valgus deformity on alignment in lower extremities after total knee arthroplasty (TKA).

To investigate the impact of knee varus and valgus in varying degrees on the alignment in lower extremities of patients who received the total knee arthroplasty (TKA). We retrospectively analyzed the condition of varus and valgus deformity in full-length X-ray films of double lower extremities in weight-bearing position of 120 patients before and after they firstly received the TKA between March 2012 and May 2014 to discover the impact of knee varus and valgus in varying degrees on the alignment in lower extremities of patients who received the total knee arthroplasty (TKA). 120 patients were divided into three groups by the pre-operative hip-knee-ankle angle (HKA), the HKAs of three groups were compared after operation, and linear regression analysis was conducted to identify the correlation between pre- and post-operative HKAs. In addition, comparison between the pre- and post-operative lean of arms and legs (LMAL) was carried out to explore the variations before and after operation as well as the differences in the average variations among three groups. The differences were statistically significant in comparison of the pre- and post-operative HKAs and medial proximal tibia angles (MPTA) of all affected extremities (p<0.05), but no statistically significant difference was shown in comparison between the pre- and post-operative knee physical valgus angles (KPVA) (p>0.05). The post-operative lengths of 86.57% of affected extremities (116/134) were longer than those before operation with statistically significant differences (p<0.05). However, no statistically significant difference was identified in comparison between the pre- and post-operative lengths of extremities that did not receive any operation (p>0.05). The ratios of HKAs between -3° and 3° in normal group, mild-deformity group and severe-deformity group were respectively 90.48%, 81.25%, and 34.69% with a statistically significant difference (p<0.05). Besides, the scatter plot revealed that there was a linear regression relation between pre- and post-operative HKAs (F=51.197, p<0.05). There were statistically significant differences in comparisons of the pre-operative KPVA and MPTAs among three groups (p<0.05). Severe knee varus and valgus deformity can increase the deviation of alignment in lower extremities after TKA, and most of LMALs after TKA are longer than those before TKA, and the most significant extension is identified in severe varus and valgus deformity.

Preoperative Measurement of Tibial Resection in Total Knee Arthroplasty Improves Accuracy of Postoperative Limb Alignment Restoration.

Background:Accuracy of implant placement in total knee arthroplasty (TKA) is crucial. Traditional extramedullary alignment instruments are fairly effective for achieving the desired mean tibial component coronal alignment. We modified the traditional tibial plateau resection technique and evaluated its effect on alignment restoration.Methods:Two hundred and eighty-two primary TKAs in our hospital between January 2013 and December 2014 were enrolled in this retrospective study. Group A consisted of 128 primary TKAs performed by one senior surgeon. Preoperative measurement of the tibial resection was conducted on radiographs, and the measured thicknesses of the lateral and medial plateau resection were used to place the tibial alignment guide. Group B consisted of 154 primary TKAs performed by the other senior surgeon, using a traditional tibial plateau resection technique. In all patients, an extramedullary guide was used for tibial resection, and preoperative and postoperative full-leg standing radiographs were used to assess the hip-knee-ankle angle (HKA), femoral component alignment angle (FA), and tibial component alignment angle (TA). A deviation ≥3° was considered unsatisfactory. Data were analyzed by unpaired Student's t-test.Results:The mean postoperative HKA and TA angles were significantly different between Groups A and B (178.2 ± 3.2° vs. 177.0 ± 3.0°, t = 2.54, P = 0.01; 89.3 ± 1.8° vs. 88.3 ± 2.0°, t = 3.75, P = 0.00, respectively). The mean postoperative FA was 88.9 ± 2.5° in Group A and 88.9 ± 2.6° in Group B, and no significant difference was detected (t = 0.10, P = 0.92). There were 90 (70.3%) limbs with restoration of the mechanical axis to within 3° of neutral alignment and 38 (29.7%) outliers (>3° deviation) in Group A, whereas there were 89 (57.8%) limbs with restoration of the mechanical axis to within 3° of neutral alignment and 65 (42.2%) outliers (>3° deviation) in Group B. The severity of the preoperative alignment deformity was a strong predictor for postoperative alignment.Conclusions:Using conventional surgical instruments, preoperative measurement of resection thickness of the tibial plateau on radiographs could improve the accuracy of conventional surgical techniques.

Significant Incidence of Extra-Articular Tibia Vara Affects Radiological Outcome of Total Knee Arthroplasty.

PurposeTo identify and quantify the presence of extra-articular tibia vara that might influence the mechanical axis alignment after total knee arthroplasty (TKA).Materials and MethodsA total of 48 TKAs in 30 osteoarthritic Indian patients were prospectively evaluated. The hip-knee-ankle angle (HKA), joint line convergence angle, and varus angulation at the femur and tibia were measured from the preoperative and postoperative standing hip-to-ankle radiographs. Four different methods were used to measure the varus angulation at the tibia: metaphyseo-diaphyseal angle (MDA), the angle between the anatomical axis and mechanical axis of the tibia, the angle between the proximal third and distal third of tibia and the angle between the proximal half and distal half of tibia.ResultsExtra-articular tibia vara quantified using MDA had the most positive correlation with HKA. Receiver operating characteristic plotting showed that MDA of >4° predicts abnormal postoperative HKA. Twenty-eight out of 48 knees had MDA of >4°, and 78.6% of these had postoperative HKA under-correction and 21.4% had less than ideal tibial component position.ConclusionsA significant inherent extra-articular varus angulation best measured using MDA exists in the proximal tibia in osteoarthritic Indian patients undergoing TKA. MDA of >4° is associated with abnormal postoperative HKA. Computer navigation may be useful for achieving ideal correction in such cases.

Postoperative Limb Alignment and Its Determinants After Minimally Invasive Oxford Medial Unicompartmental Knee Arthroplasty

One hundred twenty-two consecutive minimally invasive Oxford phase 3 medial unicompartmental knee arthroplasties in 109 patients were evaluated for postoperative limb alignment and the influence of factors such as preoperative limb alignment, age, body mass index, sex, insert thickness, and surgeon's experience. The mean mechanical preoperative hip-knee-ankle (HKA) angle of 172.2° ± 3.1° improved to 177.1° ± 2.9° postoperatively. In 75% of the limbs, the HKA angle was restored to within an acceptable alignment of 177° ± 3°, 14% of the limbs were in excessive varus (<174°), and 11% were in valgus (>180°). Only preoperative HKA angle was predictive of postoperative HKA angle. Although most of the limbs had acceptable limb alignment after unicompartmental knee arthroplasty, limbs with more severe preoperative varus deformity had a tendency to remain in excessive varus, and limbs with lesser preoperative varus deformity had a greater tendency to go into valgus postoperatively.