Mechanical Proximal Tibial Angle Research Articles

Distal femoral osteotomy for the valgus knee: indications, complications, clinical and radiological outcome

IntroductionThe aim of this study was to describe the indications and technical aspects of medial closing and lateral opening distal femoral osteotomy (MCDFO and LODFO) for patients with a valgus knee and to report clinical and radiological outcomes and complications.MethodsOver 6 years, 28 DFOs (22 MCDFO, 6 LODFO) were performed in 22 Patients. In this cohort study, we retrospectively analyzed clinical and radiological outcome measures as well as complications.ResultsThe median (range) age was 47 (17–63) years, height 1.68 (1.56–1.98) m, body mass 80 (49–105) kg, and body mass index (BMI) 27.4 (18.6–37.0) kg/m2. The clinical follow-up was 21 (7–81) months, the need for total or unicompartmental knee arthroplasty (TKA/UKA) and hardware removal was followed up for 59 (7–108) months postoperatively. Preoperatively, hip-knee-ankle angle (HKA, negative values denote varus) was 7.0 (2.0–13.0)°, mechanical lateral distal femoral angle (mLDFA) was 83.7 (79.9–88.2)°, and mechanical proximal tibial angle (MPTA) was 89.0 (86.6–94.5)°. Postoperatively, HKA was −1.3 (−9.0–1.2)° and mLDFA was 90.8 (87.3–97.3)°. The incidence of minor and major complications was 25% and 14%, the incidence of delayed and nonunion was 18% and 4%, respectively. At the last follow-up, 18% of the patients had pain at rest, 25% during activities of daily living, and 39% during physical activity, and 71% were satisfied with the outcome. 7% of the cases received a TKA/UKA, 71% received a hardware removal.ConclusionDFO is a reasonable treatment for lateral osteoarthritis in younger patients to avoid disease progression and the need for an UKA/TKA. However, there is a long rehabilitation time, a considerable risk for complications, and a high need for hardware removal. While many patients experienced symptoms at the long-term follow-up, most were satisfied with the outcome. Appropriate patient information is essential.Level of evidence Level IV, Case Series.Trial registration number NCT04382118, clinicaltrials.gov, May 11, 2020.

Predicting valgus malalignment after mobile-bearing UKA using a new method: the arithmetic HKA of the arthritic knee.

Valgus malalignment is one of the most common reasons for the progression of osteoarthritis in the lateral compartment of the knee after mobile-bearing unicompartmental knee arthroplasty (UKA). The arithmetic hip-knee-ankle angle (aHKA) of the Coronal Plane Alignment of the Knee (CPAK) classification could reflect the constitutional alignment of the arthritic knee. The purpose of this study was to observe the relationship between the aHKA and valgus malalignment after mobile-bearing UKA. This retrospective study was conducted using 200 knees undergoing UKA from January 1, 2019, to August 1, 2022. These radiographic signs, including preoperative hip-knee-ankle angle (HKA), mechanical proximal tibial angle (MPTA), mechanical lateral distal femoral angle (LDFA), and postoperative HKA, were measured using standardized weight-bearing long-leg radiographs. Patients with postoperative HKA > 180° and postoperative HKA ≤ 180° were classified as the valgus group and non-valgus group, respectively. The aHKA was calculated as 180° + MPTA - LDFA in this study, which had the same meaning as that (aHKA = MPTA - LDFA) in the CPAK classification. The Spearman correlation analysis, the Mann-Whitney U test, the chi-square test, the Fisher's exact test, and multiple logistic regression were used in the study. Of the 200 knees included in our study, 28 knees were classified as the valgus group, while 172 knees were in the non-valgus group. The mean ± standard deviation (SD) of aHKA (all groups) was 177.04 ± 2.58°. In the valgus group, 11 knees (39.3%) had a value of aHKA > 180°, while 17 knees (60.7%) had a value of aHKA ≤ 180°. In the non-valgus group, 12 knees (7.0%) had a value of aHKA > 180°, while 160 knees (93.0%) had a value of aHKA ≤ 180°. In Spearman correlation analysis, aHKA was positively correlated with postoperative HKA (r = 0.693, p < 0.001). In univariate analysis, preoperative HKA (p < 0.001), LDFA (p = 0.02), MPTA (p < 0.001), and aHKA (p < 0.001) showed significant differences between the valgus and non-valgus groups. Variables with p < 0.1 in univariate analysis were further analyzed using multiple logistic regression analysis, and the variable-aHKA (> 180° vs ≤ 180°, odds ratio (OR) = 5.899, 95% confidence interval (CI) = 1.213 to 28.686, and p = 0.028) was expressed as the risk factor of postoperative valgus malalignment. The aHKA is correlated with the postoperative alignment of mobile-bearing UKA and a high aHKA (> 180°) will increase the risk of postoperative valgus malalignment. Therefore, mobile-bearing UKA should be performed with caution in patients with preoperative aHKA > 180°.

A radiographic model predicting the status of the anterior cruciate ligament in varus knee with osteoarthritis

PurposeThe study aims to investigate the accuracy of different radiographic signs for predicting functional deficiency of anterior cruciate ligament (ACL) and test whether the prediction model constructed by integrating multiple radiographic signs can improve the predictive ability.MethodsA total number of 122 patients from January 1, 2018, to September 1, 2021, were enrolled in this study. Among them, 96 patients were classified as the ACL-functional (ACLF) group, while 26 patients as the ACL-deficient (ACLD) group after the assessment of magnetic resonance imaging (MRI) and the Lachman’s test. Radiographic measurements, including the maximum wear point of the proximal tibia% (MWPPT%), tibial spine sign (TSS), coronal tibiofemoral subluxation (CTFS), hip–knee–ankle angle (HKA), mechanical proximal tibial angle (mPTA), mechanical lateral distal femoral angle (mLDFA) and posterior tibial slope (PTS) were measured using X-rays and compared between ACLF and ACLD group using univariate analysis. Significant variables (p < 0.05) in univariate analysis were further analyzed using multiple logistic regression analysis and a logistic regression model was also constructed by multivariable regression with generalized estimating models. Receiver-operating-characteristic (ROC) curve and area under the curve (AUC) were used to determine the cut-off value and the diagnostic accuracy of radiographic measurements and the logistic regression model.ResultsMWPPT% (odds ratio (OR) = 1.383, 95% confidence interval (CI) = 1.193–1.603, p < 0.001), HKA (OR = 1.326, 95%CI = 1.051–1.673, p = 0.017) and PTS (OR = 1.981, 95%CI = 1.207–3.253, p = 0.007) were shown as predictive indicators of ACLD, while age, sex, side, TSS, CTFS, mPTA and mLDFA were not. A predictive model (risk score = -27.147 + [0.342*MWPPT%] + [0.282*HKA] + [0.684*PTS]) of ACLD using the three significant imaging indicators was constructed through multiple logistic regression analysis. The cut-off values of MWPPT%, HKA, PTS and the predictive model were 52.4% (sensitivity:92.3%; specificity:83.3%), 8.5° (sensitivity: 61.5%; specificity: 77.1%), 9.6° (sensitivity: 69.2%; specificity: 78.2%) and 0.1 (sensitivity: 96.2%; specificity: 79.2%) with the AUC (95%CI) values of 0.906 (0.829–0.983), 0.703 (0.574–0.832), 0.740 (0.621–0.860) and 0.949 (0.912–0.986) in the ROC curve.ConclusionMWPPT% (> 52.4%), PTS (> 9.6°), and HKA (> 8.5°) were found to be predictive factors for ACLD, and MWPPT% had the highest sensitivity of the three factors. Therefore, MWPPT% can be used as a screening tool, while the model can be used as a diagnostic tool.

Clinical outcomes of osteosynthesis of well-fixed periprosthetic proximal tibial fractures (Felix type 2A) after total knee arthroplasty

AimsThis study aimed to evaluate the clinical and radiologic outcomes of well-fixed periprosthetic tibial fractures after TKA. Patients and methodsThe medical records of patients who presented with Felix type 2A periprosthetic tibial fractures after TKA between March 2015 and February 2020 were retrospectively obtained from 5 institutions. Data on injury mechanism, fracture pattern including open fractures and Felix classification, and surgical method were recorded. Functional outcomes including range of motion (ROM) and Knee Society Score (KSS) at postoperative 1 year were reviewed. The need for reoperation was also reviewed. Radiologic findings included union time and mechanical proximal tibial angle (MPTA) at the last radiologic follow-up. ResultsEighteen patients (13 women, 5 men; average age, 73.9 years) were included. The average follow-up duration was 20.8 months. The fractures resulted from high-energy (11 cases) and low-energy (7 cases) injuries. Two cases involved open fractures. Anatomical locking plates were used in all cases: single plate (4 cases) and dual plates (14 cases). The average number of proximal screws was 7.1 (range, 4-9). All patients achieved bone union at an average of 18.6 weeks without secondary intervention. No infection occurred; however, 1 patient with skin necrosis required local flap. Implant removal was performed in 5 cases: 1 case, skin defect and 4 cases, discomfort due to plate prominence. The average ROM and KSS were 120.3° and 85.9, respectively. The mean MPTA was 87.8°; the MPTA was higher in the single-plate group (94.0° vs. 88.1°, p=0.013). Three cases involved values beyond the normal MPTA range (85–90°): 104° and 96° with a single plate and 92° with dual plates. The malalignment rate was higher in the single-plate group (p=0.043). ConclusionFelix type 2A periprosthetic tibial fractures treated with minimally invasive osteosynthesis showed excellent clinical outcomes, and tibial alignment was well maintained in the dual-plate group.

Single-stage total knee arthroplasty and femoral osteotomy for osteoarthritis with severe supracondylar deformity

BackgroundKnee osteoarthritis associated with extra-articular deformity (EAD) can confront the arthroplasty surgeons with challenges of bone resection and soft tissue balancing. The aim of this study was to describe a single-stage procedure associating corrective osteotomy with total knee arthroplasty (TKA), and to determine the outcome at mid- to long-term follow-up.MethodsA total of seven patients (seven knees) with knee osteoarthritis and supracondylar deformity were included in this study. Six patients were female, and one was male, with the median age of 62 years (range, 37-76 years). All patients were treated with single-stage TKA and femoral osteotomy. Osteotomy was fixed with long cemented stem. Hospital of Special Surgery (HSS) scores, collateral ligament laxity, and range of motion (ROM) were clinically evaluated preoperatively and at each follow-up. Radiographic parameters including the mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), mechanical proximal tibial angle (mMPTA), and joint line congruence angle (JLCA) were also measured. The occurrence of perioperative complications was recorded.ResultsThe median follow-up time was 91 months (range, 38-104 months). At the last follow-up, all components were stable and no patients required revision. Nonunion of the osteotomy occurred in one patient. In all patients, the lower limb mechanical alignment improved greatly. The mean angle of MAD was restored from 10.49±6.05 cm preoperatively to 1.11±4.97 cm postoperatively. The 90° mLDFA was almost acquired in all cases, with the postoperative value of 90.79±2.40°. After operation, the mMPTA improved from 84.18±6.13° to 91.33±3.13°. The JLCA changed from 2.94±1.61° to −0.71±3.50°. The median HSS score improved from 45 (range, 34-56) preoperatively to 90 (range, 82-97) postoperatively, with the outcome of all patients rated good to excellent. The median ROM improved from 70° (range 0–110°) preoperatively to 105° (range 90–125°) postoperatively. No instability of knee joint was observed. Complications included an intraoperative split fracture of distal femur and one case of wound exudation resulting from fat liquefaction.ConclusionsFor knee osteoarthritis with femoral supracondylar deformity, single-stage TKA and corrective osteotomy was feasible but technically demanding. The use of long cemented stem for osteotomy fixation can provide reliable rotational control of the bone segments.

Comparison of patient-specific distal femoral cutting guide and conventional instruments in total knee arthroplasty

Objective To design a patient-specific distal femoral cutting guide for total knee arthroplasty using rapid prototyping and 3D printing technology and compare with conventional instrumentation. Methods A prospective self-control study was performed in 32 patients who underwent bilateral total knee arthroplasty between March 2015 and November 2015 in our department. The bilateral knee joints were randomly divided into patient-specific guide group and traditional surgery group. The patient-specific guide group obtained CT data of the lower extremities preoperatively. Patient-specific distal femoral cutting guides were designed and manufactured using rapid prototyping and 3D printing techniques. The traditional surgery group were performed using conventional instrumentation. The operation time of the two groups was recorded, and the amount of distal femoral osteotomy was measured. Postoperative alignments were measured including the angle of the lower limb mechanical axis angle (hip-knee-ankle Angle, HKA), the mechanical lateral distal femoral angle (mLDFA), and the mechanical proximal tibial angle (mMPTA). In different follow-up points Hospital for Specific Surgery scores of the knee were recorded. Results In the coronal position, the postoperative mLDFA was 90.34°±1.6° in the patient-specific guide group and 91.37°±1.8° in the conventional surgery group. The difference between the two groups was statistically significant (t=-2.452, P=0.020). In the patient-specific guide group, the HKA angle was 0.36°±2.35°, and the conventional surgery group was 0.87°±1.85°. The difference between the two groups was statistically significant (t=-2.332, P=0.043). If preoperative mLDFA≤93°, there was no significant difference in postoperative mLDFA between the two groups (t=-1.409, P>0.05). If preoperative mLDFA>93°, there was a significant difference in postoperative mLDFA between the two groups (t=-4.145, P=0.004). In addition, the operation time of the patient-specific guide group was significantly shorter (t=-2.425, P<0.05), but the two groups did not have significant functional differences in the early postoperative period. Conclusion The 3D-printed patient-specific distal femoral cutting guide can significantly shorten the operation time and improve postoperative alignments. It is simple to operate. However, large sample sizes and long-term follow-up studies are still needed to verify their long-term effects. Key words: Arthroplasty, replacement, knee; Osteotomy; Imaging, three-dimensional

Coronal plane alignment of the lower limbs in patients with unilateral developmental hip dislocation.

We aimed to identify the coronal plane alignment of lower limbs in patients with unilateral developmental hip dislocation (UDHD) and observe the difference between Hartofilakidis type II and III. The radiographic data of 76 patients who met the inclusion criteria were retrospectively reviewed, including the hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), anatomical lateral distal femoral angle (aLDFA), mechanical proximal tibial angle (MPTA), and lateral distal tibial angle (LDTA). The valgus alignment on ipsilateral side was most frequently seen in both Hartofilakidis type II (51.3%) and type III groups (67.6%), whereas for the contralateral side, the neutral alignment in type II group (69.2%) and varus alignment in type III group (51.4%) were most commonly observed. Both the mLDFA and aLDFA of the ipsilateral side were significantly smaller than the contralateral side. UDHD patients may present with lower limb malalignment on both sides. The ipsilateral valgus alignment is the most common deformity. On the contralateral side, Hartofilakidis type III patients may be more prone to be varus than type II patients. The lower limb malalignment and deformity of the ipsilateral distal femur should be considered during surgery involving hip, knee, or femur.