Yoshitomo Kajino

The use of the transverse acetabular ligament in total hip replacement: An analysis of the orientation of the trial acetabular component using a navigation system

It has recently been reported that the transverse acetabular ligament (TAL) is helpful in determining the position of the acetabular component in total hip replacement (THR). In this study we used a computer-assisted navigation system to determine whether the TAL is useful as a landmark in THR. The study was carried out in 121 consecutive patients undergoing primary THR (134 hips), including 67 dysplastic hips (50%). There were 26 men (29 hips) and 95 women (105 hips) with a mean age of 60.2 years (17 to 82) at the time of operation. After identification of the TAL, its anteversion was measured intra-operatively by aligning the inferomedial rim of the trial acetabular component with the TAL using computer-assisted navigation. The TAL was identified in 112 hips (83.6%). Intra-observer reproducibility in the measurement of anteversion of the TAL was high, but inter-observer reproducibility was moderate. Each surgeon was able to align the trial component according to the target value of the angle of anteversion of the TAL, but it was clear that methods may differ among surgeons. Of the measurements of the angle of anteversion of the TAL, 5.4% (6 of 112 hips) were outliers from the safe zone. In summary, we found that the TAL is useful as a landmark when implanting the acetabular component within the safe zone in almost all hips, and to prevent it being implanted in retroversion in all hips, including dysplastic hips. However, as anteversion of the TAL may be excessive in a few hips, it is advisable to pay attention to individual variations, particularly in those with severe posterior pelvic tilt. Cite this article: Bone Joint J 2014;96-B:306–11.It has recently been reported that the transverse acetabular ligament (TAL) is helpful in determining the position of the acetabular component in total hip replacement (THR). In this study we used a computer-assisted navigation system to determine whether the TAL is useful as a landmark in THR. The study was carried out in 121 consecutive patients undergoing primary THR (134 hips), including 67 dysplastic hips (50%). There were 26 men (29 hips) and 95 women (105 hips) with a mean age of 60.2 years (17 to 82) at the time of operation. After identification of the TAL, its anteversion was measured intra-operatively by aligning the inferomedial rim of the trial acetabular component with the TAL using computer-assisted navigation. The TAL was identified in 112 hips (83.6%). Intra-observer reproducibility in the measurement of anteversion of the TAL was high, but inter-observer reproducibility was moderate. Each surgeon was able to align the trial component according to the target value of the angle of anteversion of the TAL, but it was clear that methods may differ among surgeons. Of the measurements of the angle of anteversion of the TAL, 5.4% (6 of 112 hips) were outliers from the safe zone. In summary, we found that the TAL is useful as a landmark when implanting the acetabular component within the safe zone in almost all hips, and to prevent it being implanted in retroversion in all hips, including dysplastic hips. However, as anteversion of the TAL may be excessive in a few hips, it is advisable to pay attention to individual variations, particularly in those with severe posterior pelvic tilt.

Histological finding of atypical subtrochanteric fracture after long-term alendronate therapy

Abstract Drug therapy for osteoporosis is widely accepted. Bisphosphonates in particular significantly inhibit bone resorption by suppressing osteoclast activity and increasing bone density [1–3]. Alendronate is one of these bisphosphonates; it was approved in the United States in the 1990s and is commonly prescribed worldwide [1, 4, 5]. Clinical trials have shown its effectiveness in the treatment of fractures related to postmenopausal osteoporosis [6]. However, some recent reports have described unusual subtrochanteric or femoral shaft fractures following long-term alendronate therapy [4, 7–13]. Although no causal relationship between long-term alendronate treatment and these atypical stress fractures has been established, some reports suggest that the severe suppression of bone turnover by alendronate may lead to accumulated microdamage to the bone that subsequently results in complete fracture [4, 12].

Does Degree of the Pelvic Deformity Affect the Accuracy of Computed Tomography-Based Hip Navigation?

Although some navigation systems have been used for improvement of component positioning, there have been few reports regarding cases of severe pelvic deformity. We performed a retrospective review of 25 cases of total hip arthroplasty with a computed tomography-based navigation system in patients with severe pelvic deformities and estimated acetabular component position and angle between severe deformity group and mild dysplastic group as a control. There were no significant differences in accuracy of navigation system between 2 groups in terms of 3-dimensional component position or angle. Accuracy of computed tomography-based hip navigation does not depend on the degree of pelvic deformity, and this system is also useful to identify acetabular orientation and for precise component implantation in cases of pelvic deformity.

Hemi-resurfacing versus total resurfacing for osteonecrosis of the femoral head

Purpose. To compare mid-term outcomes of hemi-resurfacing arthroplasty (HRA) and total resurfacing arthroplasty (TRA). Methods. Seven men and 5 women (16 hips) aged 33 to 72 (mean, 50) years underwent HRA, whereas 7 men and 3 women (16 hips) aged 23 to 52 (mean, 40) years underwent metal-on-metal TRA; all were for osteonecrosis of the femoral head. In the HRA and TRA groups respectively, 10 and 8 hips were steroid-induced, whereas 6 and 8 hips were related to alcohol abuse. Surgery for 12 and 4 hips entailed the posterolateral approach, whereas 4 and 12 hips entailed the Hardinge approach. Usually, HRA was performed for early stages of the disease, and TRA for more advanced stages. 12 and 6 hips were classified as JOA stages 1 to 3A, whereas 4 and 10 hips as stages 3B to 4. All the hips were JOA types C1 or C2. Results. In the HRA and TRA groups respectively, the mean follow-up period were 6.5 and 5.5 years. The mean total JOA hip scores were 57 and 54 preoperatively, 93 and 97 at one year, and 84 and 96 at the final follow-up (p<0.01). The higher score in the TRA patients was mainly attributed to improvement in the pain score. In the HRA group, 12 hips developed groin pain or groin discomfort while walking, though only 4 of them showed apparent joint-space narrowing. Five patients underwent revision surgeries (conversion to total hip arthroplasty) owing to a femoral neck fracture, acetabular protrusio, osteoarthritic change, and severe groin pain. Patients having TRA had no revision surgery and did not complain of groin pain. Implants in both groups were radiographically stable. Conclusion. TRA were superior to HRA in terms of pain relief and implant survival, even though the former procedure was used for more advanced cases.

Accurate leg length measurement in total hip arthroplasty: a comparison of computer navigation and a simple manual measurement device.

Background Several studies have shown that better placement of the acetabular cup and femoral stem can be achieved in total hip arthroplasty (THA) by using the computer navigation system rather than the free-hand alignment methods. However, there have been no comparisons of the relevant clinical advantages in using the computer navigation as opposed to the manual intraoperative measurement devices. The purpose of this study is to determine whether the use of computer navigation can improve postoperative leg length discrepancy (LLD) compared to the use of the measurement device. Methods We performed a retrospective study comparing 30 computer-assisted THAs with 40 THAs performed using a simple manual measurement device. Results The postoperative LLD was 3.0 mm (range, 0 to 8 mm) in the computer-assisted group and 2.9 mm (range, 0 to 10 mm) in the device group. Statistically significant difference was not seen between the two groups. Conclusions The results showed good equalization of the leg lengths using both computed tomography-based navigation and the simple manual measurement device.

The value of computed tomography based navigation in revision total hip arthroplasty

PurposeThis study investigates the accuracy of a computed tomography (CT)-based navigation system for accurate acetabular component placement during revision total hip arthroplasty (THA).MethodsWe performed a retrospective review of 30 hips in 26 patients who underwent cementless revision THA using a CT-based navigation system; the control group consisted of 25 hips in 25 patients who underwent cementless primary THA using the same system. We analysed the deviation of anteversion and inclination angles among the pre-operative plan, intra-operative records from the navigation system and data from postoperative CT scans.ResultsThere were no significant differences between groups (P < 0.05) in terms of mean deviation between pre-operative planning and postoperative measurements or between intraoperative records and postoperative measurements.ConclusionCT-based navigation in revision THA is a useful tool that enables the surgeon to implant the acetabular component at the precise angle determined in pre-operative planning.

Radiological assessment of the femoral bowing in Japanese population

Introduction: Differences in the magnitude of bowing between races are well-known characteristics of the femur. Asian races have an increased magnitude of femoral bowing but most of the orthopedic implants designed for the femur do not match this exaggerated bowing. We calculated the sagittal and coronal femoral bowing in the Japanese population at different levels of the femur and addressed its surgical significance. Material and methods: We calculated the sagittal and coronal bowing of 132 Japanese femora using CT scan of the femur. A mathematical calculation of the radius of curvature at proximal, middle, and distal regions of the femur was used to determine the degree of femoral bowing. Results: Mean sagittal bowing of the femur was 581, 188, and 161 mm for the proximal, middle, and distal thirds of the femur and mean lateral bowing was 528, 5092, and 876 mm, respectively. Mean sagittal and coronal bowing for the whole femur was 175 and 2640 mm, respectively. No correlation was found between age, gender, length of femur, and the degree of bowing. Conclusion: Our study reveals that femoral bowing in the Japanese population is 175 mm in the sagittal plane and 2640 mm in the coronal plane; these values are greater than the femoral bowing in other ethnic groups studied in the literature. This may result in varying degrees of mismatch between the western-manufactured femoral intramedullary implants and the Japanese femur. We recommend that orthopedic surgeons to accurately perform preoperative evaluation of the femoral bowing to avoid potential malalignment, rotation, and abnormal stresses between the femur and implant.

Three-dimensional kinetic simulation before and after rotational acetabular osteotomy

BackgroundSome reports indicate that one of major causes of clinical failure after periacetabular osteotomy is development of secondary femoroacetabular impingement (FAI). To assess the impact of range of motion (ROM) on the increase in FAI following rotational acetabular osteotomy (RAO), we performed FAI simulations before and after RAO.MethodsWe evaluated 12 hips that had undergone RAO (study group), and 12 normal hips (control group). The study group was evaluated before and after surgery. Morphological parameters were evaluated to assess acetabular coverage. The acetabular anteversion angle, anterior CE angle, alpha angle, and combined anteversion angle were also measured. Impingement simulations were performed using 3D-CT. The ROM which causes bone-to-bone impingement was evaluated in flexion (flex), abduction, external rotation at 0° flexion, and internal rotation at 90° flexion. The lesions caused by impingement were evaluated.ResultsRadiographic measurements indicated improved postoperative acetabular coverage in the study group. The crossover sign was recognized pre- and postoperatively in every case in the study group and in no cases in the control group. In the simulation study, flexion, abduction, and internal rotation at 90° flexion decreased postoperatively. Impingement occurred within 45° internal rotation at 90° flexion in two preoperative and nine postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. There were correlations between anterior CE angle, CE angle, acetabular anteversion angle, and hip flexion angle. There were also correlations between the anterior CE angle, combined anteversion angle, and angle of internal rotation at 90° flexion.ConclusionsIn the postoperative simulation, there was a tendency to reduce the ROM in flexion, abduction, and internal rotation at 90° flexion due to impingement. Since there were more cases which caused impingement within 45° internal rotation at 90° flexion after RAO, we consider there is a potential for increased FAI after RAO.

The correlation between clinical radiological outcome and contact state of implant and femur using three-dimensional templating software in cementless total hip arthroplasty.

BackgroundInitial fixation is a key factor in the success of cementless THA using a tapered wedge stem. The purpose of this study was to use three-dimensional templating software to examine the correlation between quantitative contact state and important clinical radiological outcomes, specifically stem subsidence, stress shielding, and cortical hypertrophy.MethodsWe conducted a retrospective consecutive review of 75 hips in 70 patients over a minimum 3-year follow-up period. X-rays and CT scans were investigated to assess preoperative planning, quantify the contact state of implant and femur, and assess stem alignment, stem subsidence, stress shielding, and cortical hypertrophy. We evaluated the correlation between radiological outcomes and three-dimensional quantitative contact state according to Gruen Zone in each Dorr classification.ResultsDensity mapping indicated that stem subsidence increased postoperatively if the stem had less cortical contact in the middle to distal portion of the implant in terms of initial fixation. Cases having too much cortical contact in the distal portion of the implant tended to have increased stress shielding. We found no correlation between cortical hypertrophy and the contact state of implant and femur.ConclusionsDensity mapping with three-dimensional templating software can be useful in predicting stem subsidence and stress shielding following cementless THA with a tapered wedge stem. Further analysis is required to accurately depict the correlation between cortical hypertrophy and the contact state.

Periprosthetic Occult Fractures of the Acetabulum Occur Frequently During Primary THA

BackgroundPeriprosthetic fractures of the acetabulum occurring during primary THA are rare. Periprosthetic occult fractures are defined as those not identified by the surgeon during the procedure which might be missed on a routine postoperative radiograph. However, it is unclear how frequently these fractures occur and whether their presence affects functional recovery.Questions/PurposesIn this study, using routine CT scans that were obtained as part of another primary hip arthroplasty study protocol, we retrospectively assessed (1) the prevalence of occult fractures of the acetabulum occurring during primary THA, (2) the location of occult fractures of the acetabulum during THA, and (3) risk factors contributing to such occult fractures.MethodsBetween 2004 and 2013, our institute performed 585 primary THAs (cementless or hybrid) in 494 patients with DICOM pre- and postoperative CT; during the period in question, all patients undergoing THA underwent CT before and after surgery. Preoperative CT images were taken as part of a CT-based three-dimensional templating software and navigation system. Postoperative CT images were taken an average of 1 week after surgery as part of a different protocol to evaluate cup position, restoration of leg length and offset, volume of postoperative hematoma to assess anticoagulation effects after THA, and fractures that were not found on routine postoperative radiographs (which we defined as occult fractures). Patients with a history of prior pelvic osteotomy, trauma, and infection were excluded (88 patients/99 hips); 406 patients (102 males and 304 females; 486 hips) form the basis of this report. The mean age of the patients was 60 ± 11 years, with a mean BMI of 23 ± 4 kg/m2. The mean followup of the patients with periprosthetic fracture of the acetabulum was 58 ± 28 months (range, 12–131 months). Potential risk factors for occult acetabular fracture including age, sex, BMI, preoperative diagnosis, additional dome screw fixation, composition and size of each cup, and acetabular design were examined in multivariate analysis. Acetabular component designs were categorized as true hemispheric, peripheral self-locking, and elliptical; during the period in question the indications for each cup design were based on the brand of stem used. Comparison between preoperative and postoperative CT images was done to detect the fractures. Patients with fractures identified during surgery were treated with additional dome screw fixation and a 3-week period of nonweightbearing. Patients with occult fractures in this series did not receive additional treatment as we had confirmed secure fixation of the cup during surgery.ResultsOccult fractures occurred in 41 hips (8.4%); periprosthetic fractures of the acetabulum were seen during surgery in an additional two hips (0.4%). The superolateral wall was the most frequent location for occult fractures of the acetabulum. After controlling for relevant confounding variables, only the use of peripheral self-locking cups was associated with an increased risk of occult fracture (odds ratio [OR], 2.6 compared with hemispheric cups; 95% CI, 1.2–5.6; p < 0.05). All patients with occult fractures showed bone ingrowth fixation at the final followup, without any additional surgical intervention.ConclusionsPeriprosthetic occult fractures of the acetabulum may occur relatively frequently during press-fit impaction. We observed a higher rate of fractures associated with the use of peripheral self-locking components. Occult acetabular fractures not detected on routine postoperative plain films may be ignored if secure fixation of the cup has been confirmed during the operation.Level of EvidenceLevel III, therapeutic study.