[Correlation between femoral offset, rotation center and leg length discrepancy after total hip arthroplasty based on digital analysis].

OBJECTIVE: CT scans combined with Mimics software were used to measure femoral offset (FO), rotation center height (RCH) and lower leg length discrepancy (LLD) following total hip arthroplasty (THA), and the relationship between FO, RCH and LLD after THA is discussed. METHODS: Retrospective analysis was performed on 40 patients with unilateral THA who met standard cases from October 2020 to June 2022. There were 21 males and 19 females, 18 patients on the left side and 22 patients on the right side, aged range from 30 to 81 years old, with an average age of (58.90 ±14.13) years old, BMI ranged from 17.3 to 31.5 kg·m-2 with an average of (25.3±3.4) kg·m-2. There were 30 cases of femoral head necrosis (Ficat type Ⅳ), 2 cases of hip osteoarthritis (Tönnis type Ⅲ), 2 cases of developmental hip dislocation combined with end-stage osteoarthritis (Crowe type Ⅲ), and 6 cases of femoral neck fracture (Garden type Ⅳ). Three-dimensional CT reconstruction of pelvis was taken preoperative and postoperative, and three-dimensional reconstruction model was established after processing by Mimics software. FO, RCH and LLD were measured on the model. The criteria for FO reconstruction were as follows:postoperative bilateral FO difference less than 5 mm;the standard for equal length of both lower limbs was as follows:postoperative LLD difference less than 5 mm. RESULTS: Bilateral FO difference was positively correlated with LLD (r=0.744, P<0.001). Chi-square test was performed between the FO reconstructed group and the non-reconstructed eccentricity group:The results showed that the isometric ratio of lower limbs in the FO reconstructed group was significantly higher than that in the FO reconstructed group (χ2=6.320, P=0.012). The bilateral RCH difference was significantly negatively correlated with LLD(r=-0.877, P<0.001). There is a linear relationship between bilateral FO difference and bilateral RCH difference and postoperative LLD, and the linear regression equation is satisfied:postoperative LLD=0.038x-0.099y+0.257(x:postoperative bilateral FO difference, y:postoperative bilateral RCH difference; Unit:cm), F=77.993, R2=0.808, P=0.009. CONCLUSION: After THA, LLD increased with the increase of FO and decreased with the increase of RCH. The effect of lower limb isometric length can be obtained more easily by reconstruction of FO. There is a linear relationship between the bilateral FO difference and the bilateral RCH difference after THA and LLD, and the regression equation can provide a theoretical reference for judging LLD.

Limb Length Discrepancy After Intraosseous Line Malpositioning: A Case Report.

CASE: We will present the case of a 6-year-old girl who presented with a 3-cm limb length discrepancy after intraosseous line placement at age 14 months without other known history of trauma or infection to account for the growth arrest. Imaging revealed a left proximal tibial physeal bar amenable to surgical resection with autologous lipotransfer. At 10 months postoperatively, physical examination and imaging demonstrated a stable 3-cm leg length discrepancy with an interval increase in the length of the left tibia in proportion to the growth of the right side with an increase in valgus alignment that will continue to be monitored and addressed as indicated. CONCLUSION: Pediatric intraosseous line placement presents unique challenges and can ultimately lead to physeal injury and growth arrest in the case of malpositioning.

A novel measurement approach to dynamic change of limb length discrepancy using deep learning and wearable sensors.

The accurate identification of dynamic change of limb length discrepancy (LLD) in non-clinical settings is of great significance for monitoring gait function change in people's everyday lives. How to search for advanced techniques to measure LLD changes in non-clinical settings has always been a challenging endeavor in recent related research. In this study, we have proposed a novel approach to accurately measure the dynamic change of LLD outdoors by using deep learning and wearable sensors. The basic idea is that the measurement of dynamic change of LLD was considered as a multiple gait classification task based on LLD change that is clearly associated with its gait pattern. A hybrid deep learning model of convolutional neural network and long short-term memory (CNN-LSTM) was developed to precisely classify LLD gait patterns by discovering the most representative spatial-temporal LLD dynamic change features. Twenty-three healthy subjects were recruited to simulate four levels of LLD by wearing a shoe lift with different heights. The Delsys TrignoTM system was implemented to simultaneously acquire gait data from six sensors positioned on the hip, knee and ankle joint of two lower limbs respectively. The experimental results showed that the developed CNN-LSTM model could reach a higher accuracy of 93.24% and F1-score of 93.48% to classify four different LLD gait patterns when compared with CNN, LSTM, and CNN-gated recurrent unit(CNN-GRU), and gain better recall and precision (more than 92%) to detect each LLD gait pattern accurately. Our model could achieve excellent learning ability to discover the most representative LLD dynamic change features for classifying LLD gait patterns accurately. Our technical solution would help not only to accurately measure LLD dynamic change in non-clinical settings, but also to potentially find out lower limb joints with more abnormal compensatory change caused by LLD.

Anatomical leg length discrepancy in children: Can it be accurately determined using 3-D motion capturing?

BACKGROUND: Leg length discrepancy (LLD) is common in youth and is cause by several conditions. Long leg X-rays is the gold standard technique of measuring LLD. It is highly accurate and reliable compared to clinical method, but expose the subject to radiation. Instrumented Gait Analysis (IGA) serves not only as a means to measure joint kinematics during gait but also as a valuable tool for assessing Leg Length Discrepancy (LLD) while standing. RESEARCH QUESTION: The purpose of this study was to compare different methods of determining the LLD in paediatric population. We hypothesize that IGA using joint centres is more accurate and precise than the tape measurement. METHODS: Thirty-one patients with mean age 12.3 (SD=2.4) years were retrospectively included in the study. Their LLD varied between 0 and 36 mm. Three methods for determining LLD were compared to radiography using Bland-Altman analysis: 1. Tape measurement, 2. IGA, summarizing the distance from the spina iliaca anterior superior to the medial malleolus marker via the medial knee condyle marker. 3. IGA, summarizing distances between ankle, knee, and hip joints centres where the latter is calculated with different equations. RESULTS: The IGA joints method performed better than the tape measurement or IGA markers method. The equations of Davis calculating the hip joint centre had the highest accuracy with mean difference to radiography of 0.7 mm (SD=6.3). The simple Harrington method resulted in a slightly reduced accuracy but higher precision 0.9 mm (SD=6.2). The Harrington method with leg length as input was less accurate 1.0 mm (SD=6.7), but was still considerably better than the tape measurement 1.8 mm (SD=7.0) or IGA markers method 1.1 mm (SD=11.5). SIGNIFICANCE: Determining LLD with IGA using the distances between ankle, knee and hip joints centres is a feasible method that can be applied in clinical practice to calculate LLD.

Leg length discrepancy is not a risk factor for plantar fasciitis.

PURPOSE: Plantar fasciitis (PF) is a main source of heel pain, and only about one-third of patients have bilateral symptomatic involvement, although age, body mass index (BMI), and physical activities are known risk factors. The high prevalence of unilateral involvement is poorly understood. We aimed to assess the potential association between PF and the leg length discrepancy (LLD) in unilateral PF. METHODS: A transversal case-control study was conducted from January 2019 to December 2020, including 120 participants allocated to two groups matched by BMI and sex: cases (with a diagnosis of PF; 50 ± 13 years) and control (without foot pain; 40 ± 15 years). For both groups, a difference greater than 0.64 cm in the scanometry determined the criteria for the presence of LLD. RESULTS: The multivariate logistic regression analysis showed an independent association of PF only with age (p < 0.001), and no association with LLD. We did not observe differences in the mean discrepancy (1.37 ± 0.83 cm in the PF group in comparison with 1.13 ± 0.37 cm in the control group, [p > 0.05]) or in the prevalence of LLD between groups (48% [n = 29] in the PF group compared with 42% [n = 25] in the control group, [p > 0.05]). In the PF group, 80% of the participants reported unilateral pain. We observed a higher prevalence of pain in the shorter limb (p < 0.05). CONCLUSION: Age was the only factor associated with the diagnosis of PF when groups were matched by sex and BMI. LLD was not an independent factor associated with the diagnosis of PF. However, when PF is unilateral, the shorter limb is more affected with 70% of prevalence. LEVEL OF EVIDENCE: Level III, case-control.

Arthroplasty for femoral neck fractures is at risk for under restoration of lateral femoral offset.

PURPOSE: The aim of the study was to determine the restoration of hip biomechanics through lateral offset, leg length, and acetabular component position when comparing non-arthroplasty surgeons (NAS) to elective arthroplasty surgeons (EAS). METHODS: 131 patients, with a femoral neck fracture treated with a THA by 7 EAS and 20 NAS, were retrospectively reviewed. 2 blinded observers measured leg-length discrepancy, femoral offset, and acetabular component position. Multivariate logistic regression models examined the association between the surgeon groups and restoration of lateral femoral, acetabular offset, leg length discrepancy, acetabular anteversion, acetabular position, and component size, while adjusting for surgical approach and spinal pathology. RESULTS: NAS under-restored 4.8 mm of lateral femoral offset (43.9 ± 8.7 mm) after THA when compared to the uninjured side (48.7 ± 7.1 mm, p = 0.044). NAS were at risk for under-restoring lateral femoral offset when compared to EAS (p = 0.040). There was no association between lateral acetabular offset, leg length, acetabular position, or component size and surgeon type. CONCLUSIONS: Lateral femoral offset is at risk for under-restoration after THA for femoral neck fractures, when performed by surgeons that do not regularly perform elective THA. This indicates that lateral femoral offset is an under-appreciated contributor to hip instability when performing THA for a femoral neck fracture. Lateral femoral offset deserves as much attention and awareness as acetabular component position since a secondary analysis of our data reveal that preoperative templating and intraoperative imaging did not prevent under-restoration.

Ipsilateral Healthy-segment Response to Leg Length Discrepancy.

BACKGROUND: Few studies address frequency or magnitude of healthy lower-extremity segment response to ipsilateral companion segment shortening. We sought to document and quantify this occurrence in a variety of pediatric etiologies. METHODS: We reviewed the medical record and radiographs of patients undergoing epiphysiodesis to manage leg length discrepancy. Inclusion criteria for this study were leg length discrepancy of a single lower-extremity segment by identifiable cause and adequate scanograms to allow accurate measurement of all 4 lower-extremity segments before any surgical treatment for the discrepancy. We recorded the etiology of shortening, age of onset of disorder, the length of the lower-extremity segments on scanograms, and age at the time of radiographs. We considered ipsilateral healthy-segment difference from the contralateral ≥ 0.5 cm. as clinically significant. RESULTS: Two hundred nine patients met inclusion criteria (126 boys, 83 girls). The average age was 12.5 years. 16/60 patients with avascular necrosis of the hip demonstrated ipsilateral tibial shortening averaging 1.2 cm whereas 6/60 demonstrated ipsilateral tibial overgrowth averaging 0.6 cm. 11/30 Legg-Perthés patients demonstrated ipsilateral tibial shortening averaging 0.7 cm; none had ipsilateral tibial overgrowth. 10/42 posteromedial bow patients had ipsilateral femoral shortening averaging 0.8 cm, whereas 6/42 had ipsilateral overgrowth averaging 0.8 cm. 13/48 with distal femoral physeal injury demonstrated ipsilateral tibial shortening averaging 1.2 cm, whereas 6/48 demonstrated ipsilateral tibial overgrowth averaging 0.8 cm. 8/29 tibial physeal injuries (proximal or distal) demonstrated ipsilateral femoral shortening averaging 1.1 cm. whereas 7/29 demonstrated ipsilateral femoral overgrowth averaging 0.7 cm. CONCLUSIONS: Although there are individual exceptions, the ipsilateral healthy segment does not grow appreciably more than the contralateral in patients with avascular necrosis of the hip, Legg-Perthés disease, or physeal trauma. The femur is not a significant component of shortening in patients with posteromedial bow. LEVEL OF EVIDENCE: Level III, retrospective review.

Minimal pre-operative leg length discrepancy as a risk factor of post-operative leg length discrepancy after total hip arthroplasty: a retrospective study of patients with non-traumatic osteonecrosis of the femoral head.

BACKGROUND: Leg length discrepancy (LLD) is one of the troublesome complications of total hip arthroplasty (THA). Previously, several risk factors have been suggested, but they were subjected to their inherent limitations. By controlling confounding variables, we hypothesized that known risk factors be re-evaluated and novel ones be discovered. This study aimed to analyze the independent risk factors for LLD after primary THA in patients with non-traumatic osteonecrosis of the femoral head (ONFH). METHODS: We retrospectively reviewed patients with non-traumatic ONFH who underwent unilateral THA between 2014 and 2021. All patients were operated by one senior surgeon using a single implant. Demographic data, surgical parameters, and radiological findings (pre-operative LLD, Dorr classification, and femoral neck resection) were analyzed to identify the risk factors of ≥ 5 mm post-operative LLD based on radiological measurement and to calculate odds ratios by logistic regression analysis. Post hoc power analysis demonstrated that the number of analyzed patients was sufficient with 80% power. RESULTS: One hundred and eighty-six patients were analyzed, including 96 females, with a mean age of 58.8 years at the time of initial THA. The average post-operative LLD was 1.2 ± 2.9 mm in the control group and 9.7 ± 3.2 mm in the LLD group, respectively. The LLD group tended to have minimal pre-operative LLD than the control group (-3.2 ± 5.1 mm vs. -7.9 ± 5.8 mm p = 2.38 × 10- 8). No significant difference was found between the groups in age, gender, body mass index, femoral cortical index, and implant size. CONCLUSION: Mild pre-operative LLD is associated with an increased risk of post-operative LLD after primary THA in patients with ONFH. Thus, surgeons should recognize pre-operative LLD to achieve an optimal outcome and must inform patients about the risk of developing LLD.

Effects of Artificially Induced Leg Length Discrepancy on Treadmill-Based Walking and Running Symmetry in Healthy College Students: A Lab-Based Experimental Study.

Leg length discrepancy (LLD) is a common postural deviation of musculoskeletal origin, which causes compensatory reactions and often leads to injury. The aim of the study was to investigate the effect of artificially induced LLD on gait symmetry by means of the spatiotemporal gait parameters and ground reaction forces (GRFs) using a treadmill equipped with capacitive sensors (instrumented) as well as the EMG activity of trunk and hip muscles during walking and running. Twenty-six healthy male and female college students were required to perform two sets of four 2.5-min walking and running trials on an instrumented treadmill at 5.6 and 8.1 km·h-1, respectively, without (0) and with 1, 2, and 3 cm LLD implemented by wearing a special rubber shoe. Statistical analysis was performed using one-way repeated measures or a mixed-design ANOVA. Most spatiotemporal gait parameters and GRFs demonstrated an increase or decrease as LLD increased either on the short-limb or the long-limb side, with changes becoming more apparent at ≥1 cm LLD during walking and ≥2 cm LLD during running. The EMG activity of trunk and hip muscles was not affected by LLD. Our findings showed that gait symmetry in terms of treadmill-based spatiotemporal parameters of gait and GRFs is affected by LLD, the magnitude of which depends on the speed of locomotion.

Tibial lengthening for massive distal femoral bone loss.

A man in his 30s was involved in a road traffic accident (RTA) and sustained a grade-IIIA distal femur fracture with acute loss of distal two-third of the femur. Initially, damage control surgery was done by an external fixator application. Later, staged limb reconstruction surgery was undertaken as a definitive procedure that involved bifocal distraction osteogenesis involving the proximal tibia and femur along with docking of the corticotomised femoral fragment onto the tibial plateau to achieve knee arthrodesis. The tibial and femoral regenerate together measured 25.8 cm at the end of distraction phase leaving behind a limb length discrepancy of 5 cm. Acute traumatic large bone loss is a rare presentation and is beset with unique management challenges. Limb reconstruction surgery (LRS) with LRS system provides flexibility to tackle individual case-based scenarios and helps achieve limb length, maintain alignment and restore function.

Prediction of leg-length discrepancy in pediatric femoral shaft fracture using bone SPECT/CT: A case report.

RATIONALE: Children's bones are in the process of growing in both length and width. Therefore, evaluating whether fractures affect the growth plate or not is very crucial. However, even in cases of lower limb fractures where the growth plate remains unaffected, overgrowth or shortening of the affected limb are encountered. PATIENT CONCERNS: An 11-year-old boy was admitted to the emergency department after a passenger car accident. DIAGNOSES: A comminuted fracture of the right femoral shaft was diagnosed by X-ray image. INTERVENTIONS: Closed reduction and internal fixation were performed using intramedullary titanium elastic nails. Six months after the operation, bone union was achieved and the nails were removed. OUTCOMES: Nine months after nail removal, the right leg was unexpectedly noticed 5 mm shorter than the left one. On the initial and follow-up bone single-photon emission computed tomography/computed tomography images with a 9-month interval, radioactivity of growth plate in the right proximal femur was much lower than that of the left femur, suggesting a further increasing of leg-length discrepancy (LLD) in the future. As we expected, LLD had progressively increased up to 20 mm. Epiphysiodesis was finally decided for the left distal femur. Twenty-two months after the length equalization operation, LLD decreased to 5 mm. LESSONS: This case emphasizes that quantitative analysis of growth plate activity using bone single-photon emission computed tomography/computed tomography could predict LLD and help us decide when and which limb should be operated on for pediatric patients with lower limb fractures.

Simultaneous femoral and tibial lengthening for severe limb length discrepancy in fibular hemimelia.

BACKGROUND: Fibular Hemimelia (FH) is the most common longitudinal limb deficiency. Significant limb length discrepancy (LLD) will necessitate long treatment times and multiple settings to compensate for LLD when associated with femoral shortening. This study evaluates the outcome of simultaneous femoral and tibial lengthening using the Ilizarov frame. METHODS: This retrospective study included the cases of 12 children with severe limb length discrepancy caused by combined FH and ipsilateral femoral shortening from May 2015 to August 2022. The total LLD ranged from 7 to 14.5 cm. All patients underwent single-session femoral and tibial lengthening using the Ilizarov ring external fixator technique. Additional procedures were performed in the same setting, including Achilles tendon lengthening, fibular anlage excision, peroneal tendons lengthening, and iliotibial band release. Follow-up ranged from 2 to 4 years. RESULTS: The planned limb lengthening was achieved in ten cases (83%). No cases of joint subluxation or dislocation were encountered. No neurovascular injury has occurred during the treatment course. In all cases, the bone healing index was better on the femoral side than on the tibia. Poor regeneration and deformity of the tibia occurred in two cases (16.6%). CONCLUSION: Simultaneous femoral and tibial lengthening using the Ilizarov fixator is a relatively safe procedure with the result of correction of total LLD in one session in a shorter time and less morbidity.

Fluoroscopy-guided direct anterior approach total hip arthroplasty provides more accurate component positions in the supine position than in the lateral position.

PURPOSE: The position of the acetabular and femoral components is critical for stability and wear resistance. The aim of this study is to investigate whether the fluoroscopy-guided direct anterior approach in the supine position (S-DAA) is more helpful in improving the position of acetabular and femoral components than the fluoroscopy-guided direct anterior approach in the lateral decubitus position (L-DAA). METHODS: A retrospective analysis of 76 cases of fluoroscopy-guided direct anterior approach total hip arthroplasty (38 cases in the S-DAA and 38 cases in the L-DAA group) was performed in one hospital from 2019 to 2021. The differences in inclination, anteversion, femoral offset (FO), global offset (GO), and leg length discrepancy (LLD) measurements during and after surgery were analyzed. The postoperative femoral offset (FO), global offset (GO), leg length discrepancy (LLD), and preoperative and postoperative Harris hip score were compared between the two groups. RESULTS: In the S-DAA group, there were no significant differences in the mean intraoperative inclination angle anteversion angle, FO, GO, and LLD compared to the postoperative values, whereas in the L-DAA group, there were significant differences between the intraoperative and postoperative measurements (P < 0.001, P = 0.009, P＜0.001, P＜0.001 and P = 0.008, respectively). Additionally, there were significant differences in the accuracy of LLD, FO, and GO between the two groups (P < 0.001). Compared with the L-DAA group, the average differences of inclination, anteversion, LLD, FO, and GO during and after operation in the S-DAA group were smaller, and the consistency was higher. There was a significant difference in Harris hip score between the two groups at 1 week after surgery (P = 0.033). There was no significant difference in Harris hip score between 1 month and 3 months after surgery (P = 0.482 and P = 0.797, respectively). CONCLUSIONS: In the supine group, the direct anterior approach (DAA) provides more accurate positioning of the acetabular and femoral components. However, there was no significant difference in hip joint function and activity between the two groups at follow-up.

[Risk factors of adverse long-term consequences of tibial shaft fractures in children]. / Faktory riska neblagopriyatnykh otdalennykh posledstvii pereloma diafiza bol'shebertsovoi kosti u detei.

OBJECTIVE: To analyze leg length discrepancy and overgrowth after tibial shaft fractures in children. MATERIAL AND METHODS: We analyzed medical records of 103 patients younger 14 years old with tibial shaft fractures between January 2003 and November 2018. Treatment included plastering and insertion of titanium elastic nail. To identify the risk factors of leg length discrepancy ≥1 cm and overgrowth ≥1 cm, we performed logistic regression analysis. Statistical analysis was carried out using the SPSS software for Windows. RESULTS: Gender (p=0.014) and treatment methods (p=0.011) are the most significant predictors of leg length discrepancy and overgrowth. In boys, the risk of leg length discrepancy ≥1 cm was 7.4 times higher than in girls. The risk of leg length discrepancy ≥1 cm was 4.3 times higher after insertion of titanium elastic nail compared to plastering. The risk of overgrowth ≥1 cm was 5.4 times higher in boys than in girls. The risk of overgrowth ≥1 cm was 4.7 times higher after insertion of titanium elastic nail compared to plastering. CONCLUSION: One should consider the risk of leg length discrepancy and overgrowth in children with tibial shaft fractures. This is especially true for boys undergoing insertion of titanium elastic nail.

Stricter correction of leg length discrepancy is required during total hip arthroplasty in patients with ankylosing spondylitis.

BACKGROUND: Patients with ankylosing spondylitis often have fusions in the spine and sacroiliac joints, such that it is difficult to compensate for leg length discrepancy (LLD). METHODS: We retrospectively measured the LLD after total hip arthroplasty (THA) in 89 patients with ankylosing spondylitis from June 2004 to February 2021 at our institute. Patients were divided into two groups based on an LLD of 5 mm. Clinical outcomes were investigated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Harris Hip Score (HHS). In addition, these points are investigated: patient satisfaction with the operation; whether there was a current difference in leg length; and whether there was a limping gait. RESULTS: The group with an LLD of 5-10 mm rather than < 5 mm had significantly worse WOMAC pain and stiffness. The survey revealed statistically significant differences in patient satisfaction with the operation, limping gait, and whether back pain had improved. CONCLUSION: For patients with ankylosing spondylitis, reducing the LLD to < 5 mm, which is more accurate than the current standard of < 10 mm, may produce greater improvement in clinical outcomes after hip arthroplasty.

Does the use of intraoperative measurement reduce limb length discrepancies after total hip arthroplasty?

PURPOSE: Postoperative limb length discrepancy (LLD) is a common complication of total hip arthroplasty, and several methods exist to prevent LLD, but each has its benefits and drawbacks. The study investigates the application of intraoperative lower limb length measurement in preventing postoperative LLD. METHODS: This study retrospectively analyzed 70 patients who underwent total hip arthroplasty from October 2018 to July 2022. The length of the lower limb on the operated side was measured intraoperatively using a sterilized paper ruler after the fitting of the trial mould and compared with the healthy side. Then the prosthesis size, depth and neck length were adjusted accordingly. RESULTS: The absolute value of postoperative LLD was found to be 6.68 ± 4.48 mm, of which 53 cases (75.7%) were less than or equal to 10 mm, while 30 patients (42.9%) were less than or equal to 5 mm. CONCLUSION: The use of intraoperative measurement is effective in reducing LLD after total hip arthroplasty.

New bone formation accelerates during lower limb lengthening and deformity correction in children with Ollier's disease.

BACKGROUND: Ollier's disease can cause severe length discrepancy of the lower extremities and deformity in children. Osteotomy and limb lengthening with external fixation can correct the limb deformity. This study evaluated (1) whether the duration of external fixation was reduced in patients with Ollier's disease, and (2) the incidence of complications such as pin tract infection, external fixation loosening, and joint stiffness. METHODS: Two groups were compared with respect to age, angular correction (AC), lengthening gap (LG), distraction index (DI), lengthening length (LL), lengthening length percentage (L%), lengthening index (LI), bone healing index (BHI), and external fixation index (EFI). Group 1 (Ollier's disease) comprised nine patients undergoing 11 lower limb lengthening procedures using external fixators; group 2 (control, normal lengthened bone) comprised 28 patients undergoing 29 lengthening procedures with external fixators. RESULTS: In patients with Ollier's disease, full correction of the deformity and full restoration of length were achieved in all cases. In the femur, the mean AC (15.97° vs. 6.72°) and DI (1.11 mm/day vs. 0.78 mm/day) were significantly larger, while the LI (9.71 days/cm vs. 13.49 days/cm), BHI (27.00 days/cm vs. 42.09 days/cm), and EFI (37.86 days/cm vs. 56.97 days/cm) were all significantly shorter in group 1 than in group 2 (p < 0.05). In the tibia, the mean AC and L% were larger, while the LG, LI, BHI, and EFI were all shorter in group 1 than in group 2. There was no significant difference between the two groups in the incidence of complications. CONCLUSION: In children with Ollier's disease, new bone formation accelerated and the healing speed of the lengthened segments was faster throughout the whole lengthening period with external fixation, and full correction of the deformity and full restoration of length could be achieved.

Does robot-assisted surgery reduce leg length discrepancy in total hip replacement? Robot-assisted posterior approach versus direct anterior approach and manual posterior approach: a propensity score-matching study.

BACKGROUND: Advocates of robot-assisted technique argue that robots could improve leg length restoration in total hip replacement. However, there were few studies to compare the robot-assisted posterior approach (RPA) with conventional posterior approach (PA) THA and direct anterior approach (DAA) THA in LLD. This study aimed to determine whether robot-assisted techniques could significantly reduce LLD compared to manual DAA and manual PA. METHODS: We retrospectively reviewed the cohort of consecutive ONFH patients who underwent THA robot-assisted posterior, manual posterior, and manual DAA from January 2018 to December 2020 in one institution. One experienced surgeon performed all procedures. We calculated the propensity score to match similar patients in different groups by multivariate logistic regression analysis for each patient. We included confounders consisting of age at the time of surgery, sex, body mass index (BMI), and preoperative LLD. Postoperative LLD and Harris hip scores (HHS) at two years after surgery of different cohorts were compared. RESULT: We analyzed 267 ONFH patients treated with RPA, DAA, or PA (73 RPA patients, 99 DAA patients, and 95 PA patients). After propensity score matching, we generated cohorts of 40 patients in DAA and RPA groups. And we found no significant difference in postoperative LLD between RPA and DAA cohorts (4.10 ± 3.50 mm vs 4.60 ± 4.14 mm, p = 0.577) in this study. The HHS at 2 years postoperatively were 87.04 ± 7.06 vs 85.33 ± 8.34 p = 0.202. After propensity score matching, we generated cohorts of 58 patients in manual PA and RPA groups. And there were significant differences in postoperative LLD between the RPA and PA cohorts. (3.98 ± 3.27 mm vs 5.38 ± 3.68 mm, p = 0.031). The HHS at 2 years postoperatively were 89.38 ± 6.81 vs 85.33 ± 8.81 p = 0.019. After propensity score matching, we generated cohorts of 75 patients in manual DAA and PA groups. And there were significant differences in postoperative LLD between the DAA and PA cohorts. (4.03 ± 3.93 mm vs 5.39 ± 3.83 mm, p = 0.031) The HHS at 2 years postoperatively were 89.71 ± 6.18 vs 86.91 ± 7.20 p = 0.012. CONCLUSION: This study found no significant difference in postoperative LLD between RPA and DAA, but we found a significant difference between RPA and manual PA, DAA and manual PA in ONFH patients. We found a significant advantage in leg length restoration in primary total hip arthroplasty with robot-assisted surgery.

The influence of prosthetic positioning and proximal femoral morphology on leg length discrepancy and early clinical outcomes of cementless total hip arthroplasty.

BACKGROUND: Leg length discrepancy (LLD) is a common complication of total hip arthroplasty (THA). However, the relationship between femoral prosthesis filling, proximal femoral morphology, and acetabular prosthesis positioning with postoperative LLD and clinical outcomes is unclear. The aims of this study were to investigate the influence of canal flare index (CFI), canal fill ratio (CFR), center of rotation (COR), and femoral offset (FO) on (1) postoperative LLD; and (2) clinical outcomes in the two stem designs with different coating distribution. METHODS: The study cohort included 161 patients who underwent primary cementless THA between January 2021 and March 2022 with either proximal coating or full coating stems. Multivariate logistic regression was used to assess the effect of CFI, CFR, COR, and FO on postoperative LLD, and linear regression to assess their effect on clinical outcomes. RESULTS: No statistical difference was found in clinical outcomes or postoperative LLD between the two groups. High CFI (p = 0.014), low ΔVCOR (p = 0.012), and Gender (p = 0.028) were found independent risk factors for LLD one day postoperative. High CFI was also an independent risk factor for postoperative subjectively perceived LLD (p = 0.013). CFR at the level of 2 cm below the LT (p = 0.017) was an independent risk factor for Harris Hip Score. CONCLUSIONS: Proximal femoral morphology and acetabular prosthesis positioning but not femoral prosthesis filling affected the LLD. High CFI was an independent risk factor for postoperative LLD and subjectively perceived LLD, and low ΔVCOR was also an independent risk factor for postoperative LLD. Women were susceptible to postoperative LLD.