Lower limb kinematic changes during gait after hallux valgus surgery: A prospective observational study.

BACKGROUND: Patients with hallux valgus are known to alter lower limb joint kinematics during gait. However, little information is available about gait changes following hallux valgus surgery. We aimed to longitudinally investigate lower limb kinematic changes at the mid and terminal stances of gait after hallux valgus surgery. METHODS: This prospective observational study included 11 female patients (17 feet), who underwent first metatarsal osteotomy. Gait analyses were performed preoperatively and 1- and 2-year postoperatively using a three-dimensional motion capture system. Toe-out angle, ankle, knee, and hip joint angles during gait were calculated from the recorded data. The spatiotemporal parameters and these angles at the mid and terminal stances of gait were statistically compared between preoperative and postoperative periods. FINDINGS: All spatiotemporal parameters remained unchanged postoperatively. The toe-out angle was significantly greater at 1- and 2-year postoperatively. The ankle pronation angle, the knee abduction angle, and the hip adduction angle at the mid and terminal stances of gait were smaller postoperatively compared to the preoperative. These angular changes showed a similar trend at 1 and 2 years postoperatively. However, the postoperative changes of the sagittal joint angles were relatively small. INTERPRETATION: Hallux valgus surgery can affect the toe-out angle and the lower limb coronal kinematics at the mid and terminal stances of gait in patients with hallux valgus. However, surgical correction of hallux valgus deformity did not directly improve the gait characteristics in patients with hallux valgus.

Admission screening form and osteoporosis educational appointment: a novel fracture liaison service system for identifying osteoporosis patients and facilitating medication initiation.

Our FLS team aimed to ensure that patients admitted to the orthopedic department were promptly initiated for medication and identify and initiate medication for patients admitted to other departments. Our innovative FLS system along with admission screening and osteoporosis education have proven effective in identifying patients with osteoporosis and initiating medication. PURPOSE: The fracture liaison service (FLS) plays a crucial role in the secondary prevention of fragility fractures by involving various medical professionals. Our FLS team had two goals for preventing primary and secondary fractures: ensuring that patients admitted to the orthopedic department were promptly initiated on medication and identifying and initiating medication for patients admitted to other departments. METHODS: From April 2020 to March 2023, we analyzed the number of dual-energy X-ray absorptiometry (DEXA) scans performed, the DEXA rate among patients with proximal femoral fractures, and the rate of medication initiation each year. Our hospital implemented the FLS system in April 2022. It is a unique system utilizing admission screening form and osteoporosis educational appointments conducted by rehabilitation staff to initiate medication for orthopedic and non-orthopedic patients. RESULTS: The average monthly number of DEXA scans increased significantly, with 47.7 in 2020, 57.0 in 2021, and 90.8 in 2022. The DEXA rate among proximal femoral fracture patients increased from 23.3% in 2020 to 88.1% in 2021 and 100% in 2022. The rate of treatment initiation also increased remarkably, from 21.7% in 2020, to 68.7% in 2021, reaching 97.8% in 2022. We performed 504 interventions, resulting in 251 patients diagnosed with osteoporosis, of whom 134 (56 from non-orthopedic departments) successfully started medication. CONCLUSIONS: Our innovative FLS system, incorporating an admission screening form and osteoporosis educational appointments, proved effective in identifying patients with osteoporosis and facilitating medication initiation, which will prevent both primary and secondary fractures.

Patient-Reported Outcomes of Minimally Invasive Distal Linear Metatarsal Osteotomy for Hallux Valgus.

BACKGROUND: Modified Bösch osteotomy, or distal linear metatarsal osteotomy (DLMO), is one of the minimally invasive correctional operations for hallux valgus deformity. Although the clinical and radiographic results of DLMO have been previously shown, the relationship between clinical outcomes using a validated patient-reported outcome measure and radiographic corrections have yet to be evaluated. METHODS: A total of 70 patients (97 feet) treated at our hospital were included in the study. The Self-Administered Foot Evaluation Questionnaire (SAFE-Q) and radiographic data were evaluated at a minimum 1-year follow-up. RESULTS: Scores of all five SAFE-Q subscales showed a statistically significant improvement: pain and pain-related (from 63.3 to 86.6), physical functioning and daily living (from 81.3 to 92.7), social functioning (from 79.5 to 94.4), shoe-related (from 43.1 to 72.3), and general health and well-being (from 67.7 to 92.1). The mean hallux valgus angle improved from 39.1° to 9.3°, and the mean intermetatarsal angle improved from 16.6° to 7.0°. Recurrence and hallux varus at the final follow-up occurred in nine feet (9.3%) and 15 feet (15.5%), respectively. Four of the five SAFE-Q subscale scores improved significantly even in patients with hallux varus. CONCLUSIONS: Distal linear metatarsal osteotomy improves foot-related quality of life in patients with hallux valgus deformity despite of the high rate of postoperative radiographic complication, especially hallux varus. Patients might be willing to tolerate mild hallux varus after DLMO, as indicated by patient-centered clinical results.

Isolated Talonavicular Arthrodesis for Traumatic Talonavicular Arthritis: Report of 2 Cases With Gait Analyses.

Isolated talonavicular arthrodesis is one of the surgical procedures for patients with talonavicular arthritis. However, the 3-dimensional kinematic behavior of the hip, knee, and foot/ankle complex during walking after the arthrodesis remains unclear. The clinical outcomes and gait analyses of 2 cases who underwent isolated arthrodesis for talonavicular osteoarthritis with chronic dislocated navicular fracture are presented. Gait analysis was carried out in both cases 1 year after surgery to clarify the side-to-side differences in the ranges of motion of the hip, knee, and foot/ankle complex during walking. Both cases showed good clinical results and radiographic bone union. The kinematic data of the gait analyses showed considerable restriction in the range of motion of the ankle in all 3-dimensional planes for the fused foot compared with the contralateral side. Additionally, hyperextension of the knee in the late stance of gait on the operated side was observed in both cases. When talonavicular arthrodesis was performed for talonavicular osteoarthritis with chronic dislocated navicular fracture, postoperative generalized stiffness of the ankle and future disorder of the knee should be considered.Levels of Evidence: Level V: Case report.

Author Correction: Visualization and quantification of the degenerative pattern of the talus in unilateral varus ankle osteoarthritis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Three-Dimensional Analysis of the First Metatarsal Bone in Minimally Invasive Distal Linear Metatarsal Osteotomy for Hallux Valgus.

BACKGROUND: Modified Bösch osteotomy (distal linear metatarsal osteotomy [DLMO]) is one of the minimally invasive correctional surgeries for hallux valgus. The 3-dimensional correctional angles and distances of the first metatarsal bone in DLMO have not been clarified. The purpose of this study was to analyze the 3-dimensional postoperative morphological changes of the first metatarsal bone in DLMO. METHODS: Twenty patients (30 feet) who underwent DLMO were enrolled. Preoperative plain radiographs and computed tomography (CT) scans of the feet were examined. Postoperative radiographs and CT scans were also obtained after bone union. The surface data of the pre- and postoperative first metatarsals were reconstructed from the CT data. The positions of the distal ends of the first metatarsals described with respect to the proximal ends were calculated using CT surface-matching technique. RESULTS: The distal end of the first metatarsal after DLMO was significantly supinated (10.2 ± 6.0 degrees, P < .001), adducted (6.0 ± 11.8 degrees, P = .004), dorsiflexed (11.1 ± 10.9, P < .001), shortened (7.4 ± 2.5 mm, P < .001), elevated (2.3 ± 3.1 mm, P = .001), and laterally shifted (8.2 ± 3.0 mm, P < .001) compared to the preoperative metatarsal distal end. Supination correction demonstrated a significant correlation with adduction correction (r = 0.659, P < .001) on correlation analyses between these parameters. CONCLUSION: The 3-dimensional corrections of the first metatarsal bone after DLMO were evaluated. Pronation and abduction were successfully corrected. Furthermore, adduction correction might be an important factor affecting correction of pronation. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Visualization and quantification of the degenerative pattern of the talus in unilateral varus ankle osteoarthritis.

The aim of this study was to quantify and visualize the degenerative patterns of the talus in ankle osteoarthritis (OA). The differences in talar morphology between sides of patients with unilateral varus ankle OA (medial talar tilt > 4°) were compared. Computed tomography images of both feet of 35 patients (OA: 22 patients, control: 13 patients) were analyzed. Each surface model of the right and left tali was registered to the opposite talus via a mirror-image technique and an iterative closest point algorithm. The surface deviation between the two models was quantified and visualized by deviation color maps. The results quantitatively demonstrated that osteophytes are generated in the area under the antero-medial margin of the trochlea in OA tali. In severe OA tali, bone resorption of more than 2 mm in the medial portion of the trochlea, as well as a similar degree of osteophyte formation on the lateral surface, was also seen. Stereotypical patterns of degeneration occurring in OA tali were successfully visualized and quantified by left-right comparison of patients with unilateral ankle OA. Such information would contribute to better understanding of the development of ankle OA and preoperative planning of total ankle arthroplasty and arthrodesis.

Quantification of vertical free moment induced by the human foot-ankle complex during axial loading.

Axial loading of the human cadaver lower leg is known to generate eversion of the calcaneus and internal rotation of the tibia if the plantar surface of the foot does not slide on the floor. Such kinematic coupling between calcaneal eversion and internal tibial rotation has been described previously, but no studies have actually quantified the innate ability of the human foot to generate ground reaction moment around the vertical axis of the floor (vertical free moment) due to axial loading of the human cadaver lower leg. This study investigated the vertical free moment generated by eight cadaveric lower leg specimens loaded vertically with traction of the Achilles' tendon using a six-component force plate. The vertical free moments in all specimens were oriented toward the direction of internal rotation, and the mean magnitude of the vertical free moments was -1.66 N m when an axial load of 450 N was applied. A relatively large ground reaction moment can be applied to the body during walking due to the innate structural mobility of the foot. The structurally embedded capacity of the human foot to generate the vertical free moment may facilitate compensation of the moment generated around the vertical axis of the body during walking due to trunk rotation and leg swing.

Minimally invasive distal linear metatarsal osteotomy combined with selective release of lateral soft tissue for severe hallux valgus.

BACKGROUND: Minimally invasive techniques for hallux valgus have been widely used to treat mild to moderate hallux valgus deformities. The purpose of this study was to evaluate the clinical and radiographic outcomes of distal linear metatarsal osteotomy (DLMO), which is one of the minimally invasive techniques, for severe hallux valgus. METHODS: 95 patients (141 feet) with severe hallux valgus underwent DLMOs. Lateral soft tissue release (LSTR) was performed at the same time for the cases selected by an original manual test. The satisfaction level, the Japanese Society of Surgery of the Foot (JSSF) hallux scale score, and weight-bearing radiographs of the foot were assessed preoperatively and after more than 24 months. In addition, the clinical and radiographic outcomes were compared among three groups divided by the kind of LSTR: no LSTR; manual correction; and open release through skin incision. RESULTS: Although the first metatarsal bone was significantly shortened, dorsiflexed, and elevated on postoperative radiographs, the rate of satisfaction was 87.2% (123/141), and the mean JSSF hallux scale score improved significantly from 60.4 (44-73) to 90.4 (65-100). The mean hallux valgus and intermetatarsal angles also improved significantly from 45.5° (40.0-60.0°) to 10.3° (-28.0-40.9°) and from 19.9° (14.0-28.7°) to 8.3° (-1.6-18.5°), respectively. Delayed union (18 feet), metatarsalgia (16 feet), recurrence (22 feet), and hallux varus (22 feet) were observed, and they were more obvious in DLMO combined with open release through a skin incision. CONCLUSIONS: DLMO combined selectively with LSTR is an effective procedure for correcting severe hallux valgus. However, the indication for open release with DLMO should be considered carefully.

Etiological factors in hallux valgus, a three-dimensional analysis of the first metatarsal.

BACKGROUND: It has been reported that hallux valgus (HV) is associated with axial rotation of the first metatarsal (1MT). However, the association between HV and torsion of the 1MT head with respect to the base has not been previously investigated. The present study examined whether there was a significant difference in 1MT torsion between HV and control groups. METHODS: Three-dimensional (3D) computed tomography (CT) scans of 39 ft were obtained, and 3D surface models of the 1MT were generated to quantify the torsion of the head with respect to the base. The HV group consisted of 27 ft from 27 women (69.5 ± 7.5 years old). Only the feet of HV patients with an HV angle >20° on weight-bearing radiography were selected for analysis. The control group consisted of 12 ft from 12 women (67.7 ± 7.2 years old). In a virtual 3D space, two unit vectors, which describe the orientation of the 1MT head and base, were calculated. The angle formed by these two unit vectors representing 1MT torsion was compared between the control and hallux valgus groups. RESULTS: The mean (± standard deviation) of the torsional angle of the 1MT was 17.6 (± 7.7)° and 4.7 (± 4.0)° in the HV and control groups, respectively, and the difference was significant (p < 0.01). CONCLUSIONS: This is the first study, to the best of our knowledge, to investigate 1MT torsion in HV patients using CT-based 3D analysis. The 1MT showed significant eversion in hallux valgus patients compared to control group patients.

Radiographic Shape of Foot With Second Metatarsophalangeal Joint Dislocation Associated With Hallux Valgus.

BACKGROUND: Second metatarsophalangeal (MTP) joint dislocation is associated with hallux valgus, and the treatment of complete dislocation can be difficult. The purpose of this study was to radiographically clarify the characteristic foot shape in the presence of second MTP joint dislocation. METHODS: Weight-bearing foot radiographs of the 268 patients (358 feet) with hallux valgus were examined. They were divided into 2 groups: those with second MTP joint dislocation (study group = 179 feet) and those without dislocation (control group = 179 feet). Parameters measured included the hallux valgus angle (HVA), first-second intermetatarsal angle (IMA), second MTP joint angle, hallux interphalangeal angle (IPA), second metatarsal protrusion distance (MPD), metatarsus adductus angle (MAA), and the second metatarsal declination angle (2MDA). Furthermore, the dislocation group was divided into 3 subgroups according to second toe deviation direction: group M (medial type), group N (neutral type), and group L (lateral type). RESULTS: The IPA and the 2MDA were significantly greater in the study group than in the control group. By multiple comparison analysis, the IMA was greatest in group M and smallest in group L. The IPA was smaller and 2MDA greater in group N than in group L. The HVA and MAA in group L were greatest, and MPD in group L was smallest. CONCLUSIONS: The patients with second MTP joint dislocation associated with hallux valgus had greater hallux interphalangeal joint varus and a second metatarsal more inclined than with hallux valgus alone. The second toe deviated in a different direction according to the foot shape. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Effect of tibial coronal inclination on hindfoot kinematics: A biomechanical simulation study.

Tibial coronal inclination is often recognized in everyday life, but the compensatory kinematic changes to maintain plantigrade of the hindfoot in response to tibial coronal inclination remain unclear. Lower legs and foot specimens obtained from seven human cadavers were loaded vertically with traction of Achilles' tendon in different tibial inclinations: 0° (neutral), 5°, and 10° medial inclination, and 5° and 10° lateral inclination. The orientations of the tibia, talus, and calcaneus were recorded under vertical load by a three-dimensional digitizing stylus. The angular changes of the talocrural and subtalar joints in the tibial inclinations from neutral were analyzed. The heights of the origins of the talus and calcaneus were also recorded. As the tibia was medially inclined from neutral, the talocrural joint was significantly more dorsiflexed. The subtalar joint was significantly more inverted, plantarflexed, and internally rotated. However, such significant changes in the joint angles were not observed when the tibia was laterally inclined. The height of the talus decreased as the tibia was medially inclined, but it was vice versa when laterally inclined. The compensatory motions of the hindfoot to tibial medial inclination involved coupled movement of both the talocrural and subtalar joints; such motions flatten the medial foot by decreasing the height of the talus. However, such compensatory capacities of the hindfoot to tibial lateral inclinations were limited. Tibial medial inclination under axial loading affects the kinematics of the hindfoot, and this is an important factor to consider in the treatment of flatfoot as well as foot orthotic/footwear intervention.

Responsiveness of the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) in patients with hallux valgus.

BACKGROUND: In this study, we investigated the responsiveness of the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) for patient's assessment before and after hallux valgus surgery. METHODS: Patient-reported answers on the SAFE-Q and Short Form-36 (SF-36) before and at a mean of 3-4 and 9-12 months after hallux valgus surgery were analyzed. Data of 100 patients (92 women, eight men) from 36 institutions throughout Japan were used for analysis. RESULTS: In all subscales of the SAFE-Q, the trend of increased scores after surgery was statistically significant (P < 0.001). Among the patients with available scores both before and at 9-12 months after surgery (n = 66), the largest effect sizes (ESs) were observed for shoe-related (1.60), pain and pain-related (1.05), and general health and well-being (0.84) scales. In the SF-36 (n = 64), the largest ES was observed for the bodily pain scale (0.86). Less notable changes were observed for the remaining SF-36 domains. CONCLUSION: The SAFE-Q is the first patient-reported outcome measure which includes a quality of life assessment of shoes. In our cohort, the most remarkable responsiveness was observed for the shoe-related subscale. Based on its responsiveness, the SAFE-Q appears to be sufficient for evaluation of foot-related quality of life before and after surgery.

A missense single nucleotide polymorphism in the ALDH2 gene, rs671, is associated with hip fracture.

Hip fracture is the most severe bone fragility fracture among osteoporotic injuries. Family history is a known risk factor for fracture and now included among criteria for osteoporosis diagnosis and treatment; however, genetic factors underlying family history favoring fracture remain to be elucidated. Here we demonstrate that a missense SNP in the ALDH2 gene, rs671 (ALDH2*2), is significantly associated with hip fracture (odds ratio = 2.48, 95% confidence interval: 1.20-5.10, p = 0.021). The rs671 SNP was also significantly associated with osteoporosis development (odds ratio = 2.04, 95% confidence interval: 1.07-3.88, p = 0.040). For analysis we enrolled 92 hip fracture patients plus 48 control subjects without bone fragility fractures with higher than -2.5 SD bone mineral density. We also recruited 156 osteoporosis patients diagnosed as below -2.5 SD in terms of bone mineral density but without hip fracture. Association of rs671 with hip fracture and osteoporosis was significant even after adjustment for age and body mass index. Our results provide new insight into the pathogenesis of hip fracture.

Effects of femoral bone tunnel characteristics on graft-bending angle in double-bundle anterior cruciate ligament reconstruction: a comparison of the outside-in and transportal techniques.

PURPOSE: Bone tunnel creation techniques influence the 3-dimensional (3D) position of bone tunnels and graft-bending angle in anterior cruciate ligament (ACL) reconstruction. This study assessed graft-bending angle and 3D characteristics of femoral bone tunnels and compared them between outside-in (OI) and transportal (TP) techniques. METHODS: Participants comprised 64 patients who underwent anatomic double-bundle ACL reconstruction, allocated to OI and TP groups (n = 32 each). The graft orientation plane exhibiting the largest graft-bending angle at the femoral tunnel aperture with the knee in extension was reconstructed from CT data using 3D imaging software. In this plane, graft-bending angle was compared between the OI and TP techniques. RESULTS: Although positionings of the intra-articular apertures of the femoral and tibial bone tunnels were similar, several spatial parameters of bone tunnels differed between techniques. Graft-bending angles of both anteromedial and posterolateral bundles were significantly more acute with the OI technique than with the TP technique. On coronal-plane CT, angle of the bone tunnel axis relative to the distal condylar axis correlated negatively with graft-bending angle, while in the axial plane, angle of the bone tunnel axis relative to the posterior condylar axis correlated positively with graft-bending angle. Lysholm score, pivot shift test, and anteroposterior laxity at >2.5-year follow-up demonstrated no significant differences between techniques. DISCUSSION: Different bone tunnel directions in OI and TP techniques substantially affected graft-bending angle , despite similar positionings of the intra-articular apertures. Graft-bending angle with the OI technique was acute, but risk of posterior blowout of the lateral femoral condyle was decreased. Surgeons should create the femoral tunnel while considering an obtuse graft-bending angle without increasing the risk of posterior blowout. LEVEL OF EVIDENCE: III.

Comparison between cylindrical axis-reference and articular surface-reference femoral bone cut for total knee arthroplasty.

PURPOSE: Reproducing a functional flexion-extension axis (FEA) of the femur is key to achieving successful collateral ligament balance and joint line in total knee arthroplasty (TKA). This study compared the feasibility of cylindrical axis (CA)-reference bone cut and articular surface-reference bone cuts in reproducing the FEA for Japanese osteoarthritis patients. METHODS: The study enrolled 122 knees from 86 patients who underwent primary TKA due to grade III or IV osteoarthritis. Data from pre-operative CT were reconstructed into three-dimensional (3D) models using 3D-planning software. Cylindrical radii of the condyles were measured, and femoral bone cut angles relative to anatomical landmarks were determined in the coronal and axial reference planes based on CA-reference and articular surface-reference methods. RESULTS: Mean cylindrical radii for medial and lateral femoral condyles were 17.4 ± 1.6 and 17.3 ± 1.4 mm, respectively. Of the 122 knees, 46 exhibited >1 mm of difference between condyles. Fifty-three and 22 knees exhibited >2° of angular difference between CA-reference and articular surface-reference bone cuts in the coronal and axial planes. Mean angle of the CA and surgical epicondylar axis in 3D space was 4.6 ± 2.1°. As practical parameters for TKA, the angle between CA and IM rod was significantly larger than that between the distal articular surface line and IM rod in the coronal plane (p < 0.0001), indicating that CA-reference involves a smaller valgus bone cut of the distal femur than articular surface reference. CONCLUSIONS: CA-reference bone cut of the femur is preferable to articular surface-reference bone cut for reproducing FEA in Japanese OA patients, in whom more than one-third of knees exhibited asymmetry of radii between medial and lateral condyles. In clinical practice, the CA-reference bone cut represents a good technical option for kinematically aligned TKA in the Japanese population.

Self-flip Technique of the TightRope RT Button for Soft-Tissue Anterior Cruciate Ligament Reconstruction.

The TightRope RT (Arthrex, Naples, FL) is a suspensory device for anterior cruciate ligament reconstruction. However, there is a potential risk of the button being pulled too far off the lateral femoral cortex into the soft tissue because the adjustable loop is long. The purpose of this article is to present an easy and safe technique for self-flip. As to the preparation of the graft, we draw the first line in the loop of the TightRope RT at the same length as the femoral tunnel, and we draw the second line 7 mm longer than the length of the femoral tunnel as a self-flip line. Concerning passing of the graft, the side sutures are pulled from the lateral side. We stop pulling the sutures just at the self-flip line by holding the graft at the tibial end. The side suture is inclined to the medial side with strong pulling of the suture at full extension of the knee. Then the surgeon pulls the tibial end of the graft to feel a secure positioning of the button on the lateral femoral cortex. Although it has limitations, the present technique is easy and certainly helps surgeons achieve appropriate positioning of the button.

Pseudoarthrosis of the ilium after periacetabular osteotomy that was treated by cemented total hip arthroplasty: a case report.

BACKGROUND: Preserving the hip joint to delay arthroplasty for patients with acetabular dysplasia-associated early-stage osteoarthritis has become more common, and several surgical procedures have demonstrated pain relief and improved hip joint function. Periacetabular osteotomy, one of the joint-preserving surgical procedures of the hip, provides favorable outcomes, although there are no reports of total hip arthroplasty being used to treat pseudoarthrosis of the periacetabular osteotomy segment. Therefore, we report a case of pseudoarthrosis in the osteotomy segment after periacetabular osteotomy. The patient was treated using modified total hip arthroplasty and achieved a favorable short-term outcome. CASE PRESENTATION: A 62-year-old Japanese woman was diagnosed with bilateral acetabular dysplasia at the age of 50 years, and underwent right and left periacetabular osteotomy at the ages of 52 and 55 years, respectively. When she was 61-years old, she experienced repeated episodes of left coxalgia during walking, with increasing pain at rest, and subsequently visited our department. Plain radiography and computed tomography of her left hip joint confirmed pseudoarthrosis of the periacetabular osteotomy segment. In addition, narrowing of her left hip joint space was observed, which indicated advanced osteoarthritis of the hip. Therefore, she underwent left total hip arthroplasty when she was 62-years old. During the surgery, fibrous fusion of the periacetabular osteotomy segment was confirmed via fluoroscopy, although no abnormal mobility was observed. Thus, the osteotomy segment was fixed with one absorbable screw and two bone pegs (which were prepared using allogeneic bone), and the acetabular cup was fixed using cement. Her postoperative course was generally favorable and bone fusion of the periacetabular osteotomy segment was confirmed at 3 years and 6 months after surgery. Her modified Harris hip score was 43 before the surgery and had improved to 90 at the final follow-up. CONCLUSIONS: Modified total hip arthroplasty was successfully used to treat osteoarthritis of the hip and pseudoarthrosis of the periacetabular osteotomy segment. This procedure achieved pseudoarthrosis region bone fusion and a favorable postoperative outcome.

Factors affecting the achievement of Japanese-style deep knee flexion after total knee arthroplasty using posterior-stabilized prosthesis with high-flex knee design.

BACKGROUND: Achievement of very deep knee flexion after total knee arthroplasty (TKA) can play a critical role in the satisfaction of patients who demand a floor-sitting lifestyle and engage in high-flexion daily activities (e.g., seiza-sitting). Seiza-sitting is characterized by the knees flexed >145º and feet turned sole upwards underneath the buttocks with the tibia internally rotated. The present study investigated factors affecting the achievement of seiza-sitting after TKA using posterior-stabilized total knee prosthesis with high-flex knee design. METHODS: Subjects comprised 32 patients who underwent TKA with high-flex knee prosthesis and achieved seiza-sitting (knee flexion >145º) postoperatively. Another 32 patients served as controls who were capable of knee flexion >145º preoperatively, but failed to achieve seiza-sitting postoperatively. Accuracy of femoral and tibial component positions was assessed in terms of deviation from the ideal position using a two-dimensional to three-dimensional matching technique. Accuracies of the component position, posterior condylar offset ratio and intraoperative gap length were compared between the two groups. RESULTS: The proportion of patients with >3º internally rotated tibial component was significantly higher in patients who failed at seiza-sitting (41 %) than among patients who achieved it (13 %, p = 0.021). Comparison of intraoperative gap length between patient groups revealed that gap length at 135º flexion was significantly larger in patients who achieved seiza-sitting (4.2 ± 0.4 mm) than in patients who failed at it (2.7 ± 0.4 mm, p = 0.007). Conversely, no significant differences in gap inclination were seen between the groups. CONCLUSIONS: From the perspective of surgical factors, accurate implant positioning, particularly rotational alignment of the tibial component, and maintenance of a sufficient joint gap at 135º flexion appear to represent critical factors for achieving >145º of deep knee flexion after TKA.

Effects of Reduction Osteotomy on Gap Balancing During Total Knee Arthroplasty for Severe Varus Deformity.

This study aimed to assess the effects of down-sizing and lateralizing of the tibial component (reduction osteotomy) on gap balancing in TKA, and the clinical feasibility of an uncemented modular trabecular metal tibial tray in this technique. Reduction osteotomy was performed for 39 knees of 36 patients with knee OA with a mean tibiofemoral angle of 21° varus. In 20 knees, appropriate gap balance was achieved by release of the deep medial collateral ligament alone. Flexion gap imbalance could be reduced by approximately 1.7° and 2.8° for 4-mm osteotomy and 8-mm osteotomy, respectively. Within the first postoperative year, clinically-stable tibial component subsidence was observed in 9 knees, but it was not progressive, and the clinical results were excellent at a mean follow-up of 3.3 years.