Rotational Osteotomy Research Articles

No relevant mechanical leg axis deviation in the frontal and sagittal planes is to be expected after subtrochanteric or supracondylar femoral rotational or derotational osteotomy.

The purpose of this study was to investigate if one level of corrective femoral osteotomy (subtrochanteric or supracondylar) bears an increased risk of unintentional implications on frontal and sagittal plane alignment in a simulated clinical setting. Out of 100 cadaveric femora, 23 three-dimensional (3-D) surface models with femoral antetorsion (femAT) deformities (> 22° or < 2°) were investigated, and femAT normalized to 12° with single plane rotational osteotomies, perpendicular to the mechanical axis of the femur. Change of the frontal and sagittal plane alignment was expressed by the mechanical lateral distal femoral angle (mLDFA) and the posterior distal femoral angle (PDFA), respectively. The influence of morphologic factors of the femur [centrum-collum-diaphyseal (CCD) angle and antecurvatum radius (ACR)] were assessed. Furthermore, position changes of the lesser (LT) and greater trochanters (GT) in the frontal and sagittal plane compared to the hip centre were investigated. Mean femoral derotation of the high-antetorsion group (n = 6) was 12.3° (range 10-17°). In the frontal plane, mLDFA changed a mean of 0.1° (-0.06 to 0.3°) (n.s.) and -0.3° (-0.5 to -0.1) (p = 0.03) after subtrochanteric and supracondylar osteotomy, respectively. In the sagittal plane, PDFA changed a mean of 1° (0.7 to 1.1) (p = 0.03) and 0.3° (0.1 to 0.7) (p = 0.03), respectively. The low-antetorsion group (n = 17) was rotated by a mean of 13.8° (10°-23°). mLDFA changed a mean of -0.2° (-0.5° to 0.2°) (p < 0.006) and 0.2° (0-0.5°) (p < 0.001) after subtrochanteric and supracondylar osteotomy, respectively. PDFA changed a mean of 1° (-2.3 to 1.3) (p < 0.01) and 0.5° (-1.9 to 0.3) (p < 0.01), respectively. The amount of femAT correction was associated with increased postoperative deviation of the mechanical leg axis (p < 0.01). Using multiple regression analysis, no other morphological factors were found to influence mLDFA or PDFA. Internal rotational osteotomies decreased the ischial-lesser trochanteric space by < 5mm in both the frontal and sagittal plane (p < 0.001). In case of femAT correction of ≤ 20°, neither subtrochanteric nor supracondylar femoral derotational or rotational osteotomies have a clinically relevant impact on frontal or sagittal leg alignment. A relevant deviation in the sagittal (but not frontal plane) might occur in case of a > 25° subtrochanteric femAT correction. IV.

Total hip arthroplasty using anterolateral-supine approach after transtrochanteric rotational osteotomy for osteonecrosis of the femoral head: A case report

Total hip arthroplasty using anterolateral-supine approach after transtrochanteric rotational osteotomy for osteonecrosis of the femoral head: A case report

Three-dimensional printing-assisted rotational osteotomy of the femoral neck in the treatment of early osteonecrosis of the femoral head

Rotational osteotomy of the base of the femoral neck involves osteotomy at the intertrochanteric level and rotation of the femoral head. That is to rotate the avascular collapse of the femoral head to the nonweight-bearing area of the hip joint, thus effectively avoiding further collapse of the femoral head necrosis. Clinical has achieved a certain effect. However, there are also some problems in the operation, such as the individual difference of the neck-shaft angle and the anteversion angle of the femoral neck of the affected hip joint among different patients, the nonunion of the osteotomy end, the mismatch of the relationship between the head and the acetabulum, and the direction and angle of the head rotation. The combined three-dimensional printing technology is expected to ensure the accuracy of osteotomy, to solve the adverse complications, and to improve the surgical efficacy.

Thumb and first webspace reconstruction in nonsyndromic congenital mitten hand with symbrachydactyly

Nonsyndromic congenital mitten hand with thumb and index finger syndactyly is rare. Reconstruction of this condition is challenging, requiring repositioning of the thumb and creation of a wide and deep first webspace. The aim of this paper is to describe the characteristics of patients with this condition and also to describe our surgical technique. We describe our technique in 16 consecutive children utilizing complete mobilization of the first metacarpal and thumb as an island flap on the neurovascular bundle, with a rotational osteotomy to reposition the thumb in pronation. In addition, a dorsal M flap was used to reconstruct the first webspace. Patients in this series also had varying degrees of symbrachydactyly with hypoplastic or aplastic phalanges of the central digits. There were 9 male and 7 female patients, with a mean age of 24.4±22.4 months at the time of surgery. Mean follow-up was 19.1±18.3 months. All reconstructions healed well. The mean thumb web distance in the affected hands was 4.2cm (range 3.5 to 5). All reconstructed thumbs had a good opposition. Two children initially had mild hypertrophic scarring, which resolved with pressure gloves. No other complications were observed. One-stage reconstruction of the thumb and first webspace can be effectively achieved with our technique of complete mobilization of the thumb unit, rotational osteotomy, and a dorsal interdigitating M flap.

Distal tibial osteotomy to address internal tibial torsion: Should the fibula be cut?

BackgroundRotational tibial osteotomy seeks to address pathologic tibial torsion. Inclusion of fibular osteotomy during this procedure remains controversial. This study aimed to determine how external rotation through a tibial osteotomy, with or without a fibular osteotomy, would influence tibiofibular joint congruity.MethodsEight cadaveric legs underwent distal tibial osteotomies. Pins were placed to designate neutral, 10°, 20°, 30° of external rotation. Computed tomography (CT) imaging was performed at each rotation without, then with a fibular osteotomy. Magnetic Resonance Imaging was performed prior to fibular osteotomy to confirm that ligaments remained intact. Custom software calculated tibial torsion using CT scan 3D reconstructions. Proximal tibiofibular joint rotation, distal tibiofibular gapping and ankle mortise were measured on each CT exam. Groups without and with fibular osteotomy were compared.FindingsThere was no difference between tibial osteotomy rotation magnitude with or without the fibular osteotomy (P = 0.2). The group without the fibular osteotomy had greater proximal fibular rotation at the tibiofibular joint at 20°, 30° (P < 0.05), greater posterior distal tibiofibular gap at 10°, 20°, 30° (P < 0.05) and less anterior distal tibiofibular gap at 20°, 30° (P < 0.05). The medial tibiotalar space was narrowed without the fibular osteotomy at 20°, 30° (P < 0.05) compared to pre-rotation.InterpretationDeformity at the proximal tibiofibular and ankle joints become most pronounced at >20° of tibial rotation without a fibular osteotomy. The first joint to be affected is the distal tibiofibular joint. To limit ankle and proximal tibiofibular articular deformation during tibia rotational osteotomy, a fibular osteotomy is recommended when correcting over 20° of rotation.

Femoral Osteotomies for Osteonecrosis of the Femoral Head

Femoral osteotomy is performed for osteonecrosis of the femoral head to prevent the progression of collapse and promote the repair process by transposing the necrotic lesion to the nonweight-bearing portion. The purpose of this review article was to summarize the current knowledge on two types of femoral osteotomy: transtrochanteric anterior or posterior rotational osteotomy and transtrochanteric curved varus osteotomy, both of which are currently performed for osteonecrosis, mainly in Japan and Korea. Osteotomy can be expected to cure osteonecrosis, and no matter how much the durability of artificial joints improves, there will always be young patients for whom the procedure is indicated. We should continue to verify the results of this surgery and refine the techniques involved.

Corrective Intertrochanteric Osteotomy of the Femur for Aseptic Necrosis of the Femoral Head after Bloodless Reduction of Congenital Dislocation in School-Age Children

The immediate results of treatment of 72 children aged 7 to 12 years with aseptic necrosis of the femoral head after bloodless reduction of congenital hip dislocation were analyzed. When treating patients, the following types of surgical treatment were used:extra-articular or open centering of the femoral head with intertrochanteric-torsion-varizing or devarizing and rotational osteotomy of the femur with bringing down the greater trochanter in the caudal direction. In all patients, pain and lameness disappeared, internal rotation of the lower extremities when walking, and the range of motion in the hip joint improved. Improved radiometric parameters characterizing the ratio of the acetabulum and the head of the femur and the angular values of the hip joint and proximal femur.

Management of Early Avascular necrosis of femoral head with Core Decompression and Platelet Rich Plasma infiltration

Various modalities available for the treatment of AVN range from conservative modalities like observation and non-weight-bearing mobilization, various pharmacological agents like Bisphosphonates, Enoxaparin are shown to be useful in some studies, Hyperbaric oxygen therapy to Surgical modalities like femoral head preserving procedures (core decompression with or without additional procedure, i.e. bone grafting, biologic adjuvants – Platelet Rich Plasma, Stem cells etc. and rotational osteotomies) and replacement surgeries. 20 patients of Early AVN who met inclusion criteria and operated with core decompression and PRP infiltration were included in this study. Out of 20 patients, 2 patients (10%) had superficial infections which healed on its own without any intervention, 5 patients (25%) had restriction of movements and 3 patients (15%) required replacement surgery. The mean pre-operative Harris Hip Score of our study was 64.3, and the mean post-operative Harris hip score of our study was 80.2. Out of 20 cases, 6 patients (30%) showed limitation of the progression of the disease, 3 (15%) patients progressed to the further stages of the disease and 11 patients (55%) had remission of the disease. The final outcome, on the basis of Harris Hip Score in 5 patients (25%), was excellent, 7 patients (35%) was good, 5 patients (25%) was fair, and in 3 patients (15%) was poor. Our study concludes that Core decompression along with PRP infiltration can be used as a good alternative for or in addition with traditionally performed core decompression and bone grafting.

Sliding rotational osteotomy for cases of dorsally angulated distal radius malunion: A technical note

The aim of this study was to present a novel pre-planned distal radius sliding rotational osteotomy that can address all deformities in dorsally angulated distal radius malunion through a volar approach using a locking plate. Four consecutive adult women with symptomatic dorsally angulated distal radius malunion were surgically treated with sliding rotational osteotomy. All the patients underwent preoperative Disabilities of the Arm, Shoulder and Hand (DASH) scores, a series of radiography, and a course of physiotherapy. The osteotomy was planned on 2 orthogonal radiographs, and the surgery was performed through a volar approach. A back slab was applied post-operatively for two weeks and changed to a removable splint for further four weeks. Gentle active movements out of splint were permitted at two weeks, and formal physiotherapy at six weeks post-operatively. Radiographs were taken immediately post-operatively, at three months, and with DASH scores at a mean final follow-up of 18 months. On radiographic evaluation, all the deformities were corrected within an acceptable range. The mean increase in radial inclination was 6.5 degrees. The mean gain in radial height was 2.95 mm. The mean improvement in ulnar variance was 4.25 mm. The mean change from dorsal to volar angulation was 23 degrees, and the mean improvement in the DASH score was 45.25 at a mean final follow-up of 16 months. All osteotomies achieved bony union within 3 months postoperatively. None of the patients required metalwork removal, and no complications were observed. Sliding rotational osteotomy appears to be a safe technique to correct deformity and improve function in patients with dorsally angulated, shortened, and radially deviated distal radius malunion.

Comparison of an oblique single cut rotation osteotomy with a novel 3D computer-assisted oblique double cut alignment approach

An oblique double-cut rotation osteotomy (ODCRO) enables correcting a complex bone deformation by aligning, in 3D, the distal, middle and proximal bone segments with a target bone, without intersegmental gaps. We propose virtual preoperative planning of an ODCRO. To minimize a residual translation error, we use an optimization algorithm and optimize towards bone length, alignment in the transverse direction, or a balanced reconstruction. We compare the residual alignment error with an oblique single-cut rotation osteotomy using 15 complex bone deformations. The single-cut approach was not feasible in 5 cases, whereas the ODCRO procedure was feasible in all cases. The residual alignment error was smaller for the ODCRO than for the single-cut approach except for one case. In a subset for length reconstruction, the length error of 7.3–21.3 mm was restored to 0.0 mm in 4 of 5 cases, although at the cost of an increased transverse translation. The proposed method renders planning an ODCRO feasible and helps restoring bone alignment and lengthening better than an oblique single-cut rotation osteotomy. Awareness of the challenges and possibilities in preoperative planning of an ODCRO will be of value for future alignment surgery and for patients.

Evaluation of transtrochanteric rotational osteotomy for avascular necrosis of hip: a case series

&lt;p class="abstract"&gt;Osteonecrosis, also referred to as avascular necrosis (AVN), aseptic necrosis and ischemic necrosis, is not a specific disease but rather a condition in which a circumscribed area of bone becomes necrotic as a result of a loss of its blood supply. The femoral head is the site most often affected and its frequent cause is a displaced fracture through the femoral neck. This is a case-series study that has been done on 9 patients (10 hips) with clinical and radiological evidence of osteonecrosis of head of femur. After treatment patients were followed clinically and radiographically at 1 to 3 months intervals during first year after the operation and at 3 to 6 months intervals thereafter. Out of 9 study subjects, 7 (77.7%) were male and 2 (22.2%) were female. Mean age was 40±7.5. Among 7 (70%) hips, canulated cancellous screws were used and dynamic hip screw were used in 3 (30%) hips. Majority of the cases, 4 (40%) had more than 2 mm of progressive collapse of transported intact area in their latest follow up. Transtrochanteric rotational osteotomy procedure is valuable and needs to be tried by new genre of orthopedician as it helps in clinical improvement of patient and might also delay the necessity for total hip arthroplasty.&lt;/p&gt;

Complications of hip preserving surgery

Preoperative evaluation of the pathomorphology is crucial for surgical planning, including radiographs as the basic modality and magnetic resonance imaging (MRI) and case-based additional imaging (e.g. 3D-CT, abduction views).Hip arthroscopy (HAS) has undergone tremendous technical advances, an immense increase in use and the indications are getting wider. The most common indications for revision arthroscopy are labral tears and residual femoroacetabular impingement (FAI).Treatment of borderline developmental dysplastic hip is currently a subject of controversy. It is paramount to understand the underlining problem of the individual hip and distinguish instability (dysplasia) from FAI, as the appropriate treatment for unstable hips is periacetabular osteotomy (PAO) and for FAI arthroscopic impingement surgery.PAO with a concomitant cam resection is associated with a higher survival rate compared to PAO alone for the treatment of hip dysplasia. Further, the challenge for the surgeon is the balance between over- and undercorrection.Femoral torsion abnormalities should be evaluated and evaluation of femoral rotational osteotomy for these patients should be incorporated to the treatment plan.Cite this article: EFORT Open Rev 2021;6:472-486. DOI: 10.1302/2058-5241.6.210019

Supracondylar rotation osteotomy of the femur influences the coronal alignment of the ankle

PurposeOsteotomies represent well-established treatment-options for the redistribution of loads and forces within and around the knee-joint. Effects of these osteotomies on the remaining planes and adjacent joints are not fully understood. The aim of this study was to determine the influence of a distal-femoral-rotation-osteotomy on the coronal alignment of the ankle. It was hypothesized that supracondylar-external-rotation-osteotomy of the distal femur leads to a change in the coronal orientation of the ankle joint.MethodsLong-leg standing radiographs and CT-based torsional measurements of 27 patients undergoing supracondylar-rotational-osteotomy of the femur between 2012 and 2019 were obtained and utilized for the purpose of this study. Postoperative radiographs were obtained after union at the osteotomy-site. The hip-knee-ankle-angle (HKA), the mechanical-lateral-distal-femur-angle (mLDFA), and Tibia-Plafond-Horizontal-Orientation-Angle (TPHA) around the ankle were measured. Comparison between means was performed using the Wilcoxon-Mann–Whitney test.ResultsTwenty-seven patients with high femoral antetorsion (31.3° ± 4.0°) underwent supracondylar-external-rotation-osteotomy. The osteotomy led to a reduced antetorsion (17.4 ± 5.1; p < 0.001) and to a valgisation of the overall limb-alignment. The HKA decreased by 2.4° ± 1.4° (p < 0.001). The TPHA decreased by 2.6° (p < 0.001).ConclusionsSupracondylar external rotation osteotomy of the femur leads to lateralization of the weight bearing line at the knee and ankle due to valgisation of the coronal limb alignment. The mobile subtalar joint has to compensate (inversion) for the resulting valgus orientation of the ankle to ensure contact between the foot and the floor. When planning a rotational osteotomy of the lower limb, this should be appreciated – especially in patients with a preexisting valgus alignment of the lower extremities or restricted mobility in the subtalar joint.

Improved Ilizarov method for management of deformity and ulceration on foot and ankle of spina bifida.

ObjectiveTo analyze the characteristics of foot and ankle deformity with ulceration in patients with spina bifida, to conclude experiences on management with improved Ilizarov method in one stage.Methods77 cases suffering foot and ankle deformity with ulceration of spina bifida were included from January 2008 to June 2019, in which 30 male and 47 female, aged 6–46 years with an average age of 22.86 years. There were 10 cases on left, 14 on right and 53 on both. The improved Ilizarov method combined soft tissue surgery, bone osteotomy and Ilizarov technique in one stage, by which the ulcer was dressed aseptically and avoid weight bearing preoperatively, no special treatment, no debridement, no flap coverage and no bacterial culture. Antibiotics were given for 3 days routinely, and the dressing was removed 5 days later. If there was exudation, gauze could be used to wrap continually, if there was no swelling and exudation, no need further more caring. General appearance and radiological image of ulcer and deformity were observed during the period of evaluation and treatment, surgical method and complications, foot & ankle function and overall function were evaluated using AOFAS scoring system and special table designed by authors.Results77 cases were followed up for 6–132 months with an average of 50.5 months. Achilles tendon subcutaneous lengthening was performed in 2 cases, posterior tibial tendon and Achilles tendon simultaneous released for 31cases, subtalar joint arthrodesis 25 cases, calcaneus osteotomy 5 cases, triple osteotomy 28 cases, ankle arthrodesis 19 cases, internal rotation osteotomy of tibia was performed in 1 case and 1 case in external rotation osteotomy. There were 67 cases using Ilizarov fixators and 10 cases using Hybrid fixators for immobilization and correction. Stable feet were obtained and ulcers healed simultaneously when all deformities of foot and ankle had been corrected. The healing time of ulcer was average 26.5 days ranging 7–36 days, and there was no infection or delayed healing occurred in any case. Ankle ankylosis in 25 cases, 3 cases of pin tract infection, 2 wires were broken. The AOFAS score significantly increased from 70.5 ± 4.5 preoperative to 81.6 ± 3.9 postoperative; based special table evaluating, Excellent 28 cases, Good 42 cases, Fair7 cases.ConclusionThe patients with foot & ankle deformity and ulceration suffered from spinal bifida can be treated by improved Ilizarov method in one stage, and the results are satisfactory with short treatment period and decreased complications.Translational potential of this articleThe characteristics of foot and ankle deformity with ulceration inpatients with spina bifida have been analyzed and the experiences on management with improved Ilizarovmethod in one stage have been summarized in this study, which updated treatment concept of neurogenic deformity with ulceration on foot and ankle joint.

Femoral neck rotational osteotomy: a modified method for treating necrotic femoral heads with large and laterally located lesions.

In this study, we retrospectively investigated the short-term outcome of femoral neck rotational osteotomy (FNRO) for treating necrotic femoral heads with large and laterally located lesions. Twelve necrotic femoral heads (ARCO stage II or III) with an average Kerboul angle of 210° underwent FNRO through surgical hip dislocation. By circumferential release of capsule and retinaculum, femoral neck osteotomy was performed at the base of femoral neck just 1.5 cm above lesser trochanter. The severed femoral neck was rotated with a mean angle of 120.4° and fixed with a mean varus angulation of 10.2°. Both Harris hip score and International hip outcome tool improved at a mean follow-up of 29 months. The average post-operative intact rate was 55.3%. Subsequent collapse or progression to osteoarthritis was found in four hips but only one hip failed with a Harris hip score of 44 and converted to hip replacement. Post-operative leg length discrepancy was 1.1 cm. Limp presented in seven hips. Six hips had osteophyte formation. FNRO through surgical hip dislocation had the advantages of safe exposure, direct visualization of necrotic lesion and high reorientation of healthy bone and articular cartilage on femoral head. We observed satisfactory short-term survivorship and improved patient-reported outcomes in necrotic femoral heads treated with FNRO.

Vertebral Body Rotational Osteotomy for Decompressing an Eccentrically Protruded Ossification of the Posterior Longitudinal Ligament: A Technical Note.

Vertebral body sliding osteotomy has been reported as a technique to manage cervical myelopathy caused by ossification of the posterior longitudinal ligament. It involves mobilization and anteriorly translating the vertebral body and ossified mass as a whole. The main advantage of the procedure is decreased rate of complication such as dural tear, implant dislodgement, and pseudarthrosis, which demonstrates high rate in anterior cervical corpectomy and fusion. Vertebral body rotational osteotomy is a modification of vertebral body sliding osteotomy. It is indicated for laterally deviated ossified mass to achieve further decompression. This is a technical note describing the procedures of vertebral body rotational osteotomy.

Application of 3-Dimensional Printing Technology in Rotational Osteotomy of Congenital Radioulnar Synostosis

To investigate whether computer-aided design (CAD) and 3-dimensional printing technology can assist in accurate completion of ulna-radius proximal rotational osteotomy in congenital radioulnar synostosis (CRUS). We treated 1 right arm and 4 left arms of 4 boys with a mean age of 5.2 years (range, 4.3-6.0 years) between July 2018 and April 2019. Computed tomography (CT) scans of the forearm were performed on the children before surgery. Using the CT data, the pronation angle of the forearm was measured. An individualized dial with a matching forearm diameter was designed before surgery to control the angle of the rotational osteotomy. Ulna and radius models, and individualized dials, were prepared for each patient using 3-dimensional printing technology. Preoperative simulated surgery was performed using the 3-dimensional printed models. During the surgery, 2 Kirschner wires were used as operating levers for rotation, and rotational angle correction was precisely controlled using the dial. The cast and internal fixation were removed after x-ray examination showed that the osteotomy had healed, about 5 weeks after surgery. The rotational osteotomies were completed in a single operation, and the correction angle was 60°. No complications occurred after the operation. All patients showed functional improvements in activities of daily living. For CRUS patients, models and dials made with CAD and 3-dimensional printing technology can assist in precise rotational osteotomy. Therapeutic V.

Factors Influencing Outcomes of the Dysplastic Hip in Nonambulatory Children With Cerebral Palsy.

Hip dysplasia in the nonambulatory child with spastic cerebral palsy (CP) is a common condition not always effectively treated with conservative measures even when recognized early. Optimal surgical intervention strategies and timing are not clear from previous studies. Contralateral hips with less severe subluxation in these patients also often undergo surgery and little is known of outcomes of these less severe hips. This study aims to clarify treatment factors related to long term success following hip surgery for subluxation in nonambulatory children with CP. A total of 183 nonambulatory subjects with CP and a minimum of 2-year follow-up were included. All subjects underwent varus rotational osteotomy of the femur; other surgical factors considered were addition of pelvic osteotomy (PO), capsulorrhaphy, and soft tissue releases. Additional factors studied were age at index surgery, sex, and unilateral versus bilateral surgery. Severely subluxated (SS) hips, defined as having >50% migration, were studied separately from contralateral nonsevere hips. Surgeries were deemed successful if final follow-up indicated a migration of <25%; patients with any revision surgeries or >25% migration were categorized as failures. A 60% success rate was found in SS hips and a 68% success rate in nonsevere hips. Age at index surgery did not influence success rates in SS hips. In the nonsevere hips, success was associated with index surgery at older age. The addition of a PO was the only concomitant procedure demonstrated to improve outcomes. In SS hips, those with a successful outcome were 2.5 times more likely to have had a PO. The addition of capsulorrhaphy had a negative effect on the entire group, reducing odds of success to 0.8. No other factors were significant. The findings from this multicenter retrospective study suggest that PO be added to varus rotational osteotomies in patients with severe hip subluxation. Surgery should be undertaken for severe dysplasia without concern for age. The addition of capsulorrhaphy does not improve rate of success. Level III-retrospective comparative study.

Reflections on Rotational Osteotomies around the Patellofemoral Joint.

Torsional abnormalities of the femur represent a significant risk factor for patellar instability or patellofemoral complaints. Although their clinical implication has been demonstrated, there is still a debate going on about different aspects. These include, especially, the various methods of measurements with a wide range of physiologic values, the indication or clear recommendation for surgical correction, and the site of the rotational osteotomy. Nevertheless, good subjective and objective functional results were reported after femoral rotational osteotomies. This is mostly not a review of the literature, but a collection of personal thoughts and observations.

How does transtrochanteric anterior rotational osteotomy change the dynamic three-dimensional intact ratio in hips with osteonecrosis of the femoral head?

BackgroundThe intact ratio (the ratio of the intact area of the femoral head) on a two-dimensional anteroposterior radiograph is associated with the prognosis of hips with osteonecrosis of the femoral head after transtrochanteric anterior rotational osteotomy. However, changes of the three-dimensional intact ratio during dynamic weight-bearing activity and correlation of the three-dimensional intact ratio with clinical scores are still unknown. MethodsKinematics of eight hips with osteonecrosis of the femoral head that underwent anterior rotational osteotomy were analyzed using image-matching techniques during chair-rising and squatting preoperatively and postoperatively. Two types of dynamic three-dimensional intact ratios were examined, including the lunate covered area (IRLC) and in vivo peak contact force vector intersected area (IRFV). The static three-dimensional intact ratio in each octant of the femoral head was also examined. FindingsThe mean Harris hip score significantly improved from 67 preoperatively to 90 postoperatively. During chair-rising rising/squatting, the mean IRLC and IRFV significantly increased from 42%/41% and 7%/4% preoperatively, to 66%/65% and 79%/77% postoperatively, respectively. IRLC significantly changed during the motion whereas substantial postoperative IRFV was maintained throughout the motion. Additionally, Harris hip score and the static three-dimensional intact ratio in the superolateral regions had significant positive correlations with both IRLC and IRFV. InterpretationHip kinematics affected IRLC but not IRFV, which suggests that substantial intact bone occupies the region in which peak contact forces are applied during deep hip flexion. Additionally, improving intact ratio in the superolateral region led to improvements in both IRLC and IRFV with favorable clinical scores.