Aims: The Coronal Plane Alignment of the Knee (CPAK) classification is a simple and comprehensive system for predicting pre-arthritic knee alignment. However, when the CPAK classification is applied in the Asian population, which is characterized by more varus and wider distribution in lower limb alignment, modifications in the boundaries of arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) should be considered. The purposes of this study were as follows: first, to propose a modified CPAK classification based on the actual joint line obliquity (aJLO) and wider range of aHKA in the Asian population; second, to test this classification in a cohort of Asians with healthy knees; third, to propose individualized alignment targets for different CPAK types in kinematically aligned (KA) total knee arthroplasty (TKA). Methods: The CPAK classification was modified by changing the neutral boundaries of aHKA to 0° ± 3° and using aJLO as a new variable. Radiological analysis of 214 healthy knees in 214 Asian individuals was used to assess the distribution and mean value of alignment angles of each phenotype among different classifications based on the coronal plane. Individualized alignment targets were set according to the mean lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) of different knee types. Results: A very high concentration, 191 from 214 individuals (89.3%), were found in knee types with apex distal JLO when the CPAK classification was applied in the Asian population. By using aJLO as a new variable, the high distribution percentage in knee types with apex distal JLO decreased to 125 from 214 individuals (58.4%). The most common types in order were Type II (n = 70; 32.7%), Type V (n = 55; 25.7%), and Type I (n = 46; 21.5%) in the modified CPAK classification. Conclusion: The modified CPAK classification corrected the uneven distribution when applying the CPAK classification in the Asian population. Setting individualized TKA alignment targets according to CPAK type may be a practical method to recreate optimal LDFA and MPTA in KA-TKA. Cite this article: Bone Jt Open 2022;3(3):211–217.

Background: Although varus inclination of the tibial plateau has increasingly been recognized as a major risk factor in the progression of Osteoarthritis of the knee (OA knee), little attention has been placed on the development of the varus inclination of the tibial plateau. Osteoporosis is a disease characterized by low bone mass and may increase the risk of a stress fracture in the proximal tibia. To date, risk factors for varus inclination of the tibial plateau are rarely reported. In this study, we investigated Bone Mineral Density (BMD) as a risk factor of varus inclination of the tibial plateau in postmenopausal women with advanced OA knee. Methods: A total of 90 postmenopausal women with varus OA knee who had received a total knee arthroplasty in our department between January 2016 and December 2019 were reviewed. Certain factors may correlate to inclination of the tibial plateau (Medial Tibial Plateau Angle, MTPA), including age, operation side, Kellgren-Lawrence grade of OA knee, BMD, Body Mass Index (BMI), Lateral Distal Femur Angle (LDFA), lower extremity alignment (Hip-Knee-Ankle angle, HKAA), and history of both spinal compression fracture and hip fracture were collected and analyzed. Results: Osteoporosis, lower extremity varus malalignment and age were significantly associated with varus inclination of the tibial plateau (MTPA) (P = 0.15, 0.013 and 0.033 respectively). For patients with a lower extremity varus malalignment (HKAA < 175°), osteoporosis (T-score ≤ -2.5) was significantly associated with inclination of the tibial plateau. For patients with a normal lower extremity alignment (HKAA ≥ 175°), no significant association was found between osteoporosis (T-score ≤ -2.5) and varus inclination of the tibial plateau. Conclusions: Osteoporosis, lower extremity varus malalignment and age are major risk factors for inclination of the tibial plateau in postmenopausal women with OA knee. More attention needs to be given to the progression of varus OA knee in postmenopausal women who simultaneously has osteoporosis and lower extremity varus malalignment.

Background: The kinematic alignment (KA) technique in total knee arthroplasty (TKA) aims to restore the native alignment of pre-disease knee joint anatomy. Determining the individualized alignment targets is crucial for pre-operative planning, which can be set according to different original knee phenotypes. Five most common knee phenotypes have been categorized for KA-TKA alignment target setting in our previous study. The purpose of this study was to investigate the distribution of the five phenotypes in advanced OA knee patients and evaluate the clinical outcomes of this phenotype-oriented KA-TKA using the generic instrument, with particular emphasis on alignment strategy, surgical technique, survivorship, radiographic and functional outcomes. Methods: The clinical data of 123 patients (88 women, 35 men) who had undergone 140 TKAs in our hospital were reviewed. All the TKAs were performed with alignment targets set according to the original phenotypes of the knee, with the KA method, using the generic total knee instrument. The patients’ demographics, preoperative and postoperative knee alignment angles, one-year postoperative range of motion (ROM), Oxford knee scores (OKS), Combined knee society score (CKSS) were collected and analyzed. Results: The 3 years survivorship was 99.3% for all cause of revision, and 100% with revision other than infection as the endpoint. The preoperative phenotypes of the knee were as follows: neutral alignment 20.1% (type 1: 3.6%, type 2: 16.5%), varus alignment 71.2% (type 3: 46.0%, type 4: 25.2%), and valgus alignment (type 5: 8.6%). Using our protocol, patients with different knee phenotypes could get similar great functional improvement though the postoperative alignment parameters were significantly different between the knee phenotypes (P < 0.05). Conclusion: The early outcomes of this phenotype-oriented KA-TKA using generic total knee instruments are promising. Setting individualized alignment target according to original knee phenotype is rational and practical. The residual varus alignment did not cause any aseptic loosening in the 3 years follow-up. Long-term survivorship and functional outcomes need to be evaluated in future studies.

Backgrounds: A common sequela of hip fracture is loss of ambulation capacity. Prediction of postoperative ambulation capacity is important for surgical and rehabilitation decision making. Handgrip strength is a quick and convenient tool for evaluating postoperative functional ability and outcome in variety of clinical conditions for the elderly and is associated with the use of walking aids. We propose that handgrip strength may be a good predictor for postoperative early ambulation. The purpose of our study was to investigate the contribution of handgrip strength in the prediction of postoperative early ambulation capacity in elderly hip fracture patients. Methods: Clinical data of patients with low-energy hip fractures who received surgery from Jan 2018 to Dec 2019 were prospectively collected. The correlations of ambulation time with complication rate, age, gender, injured side, fracture classifications, surgical procedure, body mass index (BMI), and handgrip strength were analyzed. Results: Sixty-three hip fracture patients were included in this study. Patients whose ambulation time was less than 3 days after the operation had significantly fewer postoperative complications (P = 0.006). Handgrip strength showed the strongest correlation with postoperative early ambulation capacity (P = 0.004). The handgrip strength threshold value for early ambulation was found to be 20.5 kg for male patients and 11.5 kg for female patients. Conclusion: Handgrip strength testis a quick and convenient tool for predicting postoperative early ambulation capacity. In elderly Asians, male patients with a handgrip strength above 20.5 kg and female patients with a handgrip strength above 11.5 kg suggest a high likelihood of early postoperative ambulation and a lower risk of complications after the hip surgery.

The aim of our study was to investigate failure rates of reconstruction plate and non-reconstruction plate, and find the best strategy for implant selection for different fracture types for midshaft clavicular fractures. Two hundred twenty-six consecutive patients with midshaft clavicular fractures who received open reduction and plate fixation during Jan 2012 to July 2017 were reviewed. The correlations between implant failure rates and risk factors including demographic data, fracture classifications, and implant types were analyzed. AO/OTA fracture classification and plate types are the most important factors affecting implant failure for midshaft clavicular fractures. Reconstruction plate had a significantly higher failure rate (53%) than that of non-reconstruction plates (3%) in comminuted midshaft clavicular (AO/OTA 15-2C) fractures (P value < 0.01). However, the difference was not significant in AO/OTA 15-2A and 2B classifications. Patients with comminuted midshaft clavicular (AO/OTA 15-2C) fractures treated with reconstruction plates had very high implant failure rates compared to non-reconstruction plates. We suggested that patients with comminuted midshaft clavicular (AO/OTA 15-2C) fractures treated with reconstruction plates need more protection and more frequent follow-up in the postoperative period.

Background: Metacarpal shaft fracture is a common fracture in hand trauma injuries. Surgical intervention is indicated when fractures are unstable or involve considerable displacement. Current fixation options include Kirschner wire, bone plates, and intramedullary headless screws. Common complications include joint stiffness, tendon irritation, implant loosening, and cartilage damage. Objective: We propose a modified fixation approach using headless compression screws to treat transverse or short-oblique metacarpal shaft fracture. Materials and methods: We used a saw blade to model transverse metacarpal neck fractures in 28 fresh porcine metacarpals, which were then treated with the following four fixation methods: (1) locked plate with five locked bicortical screws (LP group), (2) regular plate with five bicortical screws (RP group), (3) two Kirschner wires (K group), and (4) a headless compression screw (HC group). In the HC group, we proposed a novel fixation model in which the screw trajectory was oblique to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; thus, the screw did not damage the articular cartilage. The specimens were tested using a modified three-point bending test on a material testing system. The maximum fracture forces and stiffness values of the four fixation types were determined by observing the force–displacement curves. Finally, the Kruskal–Wallis test was adopted to process the data, and the exact Wilcoxon rank sum test with Bonferroni adjustment was performed to conduct paired comparisons among the groups. Results: The maximum fracture forces (median ± interquartile range [IQR]) of the LP, RP, HC, and K groups were 173.0 ± 81.0, 156.0 ± 117.9, 60.4 ± 21.0, and 51.8 ± 60.7 N, respectively. In addition, the stiffness values (median ± IQR) of the LP, HC, RP, and K groups were 29.6 ± 3.0, 23.1 ± 5.2, 22.6 ± 2.8, and 14.7 ± 5.6 N/mm, respectively. Conclusion: Headless compression screw fixation provides fixation strength similar to locked and regular plates for the fixation of metacarpal shaft fractures. The headless screw was inserted obliquely to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; therefore the articular cartilage iatrogenic injury can be avoidable. This modified fixation method may prevent tendon irritation and joint cartilage violation caused by plating and intramedullary headless screw fixation.