Tomoharu Takagi

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.

Iodine-Supported Hip Implants: Short Term Clinical Results

We developed a new povidone iodine coating technology for titanium hip implants and performed a clinical trial to assess its usefulness in suppressing postoperative infection. Results indicate that iodine-supported titanium has favorable antibacterial activity, biocompatibility, and no cytotoxicity. Thirty joints in 28 patients were treated using iodine-supported implants. Fourteen joints were revision total hip arthroplasty (THA) after periprosthetic infection, 13 were primary THA for immunosuppressive conditions or pyogenic arthritis, and 3 were conversions from hemiarthroplasty to THA for immunosuppressive conditions. Two examinations were conducted sequentially until final follow-up: white blood cell (WBC) and C-reactive protein (CRP) were measured pre- and postoperatively and thyroid hormone levels in the blood were examined. The mean follow-up period was 33 months (14–78). There were no signs of infection in any patient at the last follow-up. WBC and CRP levels returned to normal within several weeks. No abnormalities of thyroid gland function were detected. Loosening of the implants did not occur in any patient. Excellent bone ingrowth and ongrowth were found around prostheses. No cytotoxicity or adverse effects were detected. These results suggest that iodine-supported THA implants can be highly effective in preventing and treating postoperative infections.

Three-dimensional limb lengthening after total knee arthroplasty in a simulation study

Abstract Objectives: Limb lengthening after total knee arthroplasty (TKA) has been reported in some cases, all of which were evaluated using two-dimensional images. To our knowledge, no case has been evaluated using three-dimensional (3D) images. We investigated 3D limb lengthening after TKA. Methods: We simulated 100 varus knees using 3D templating software. Virtual TKA was performed to maintain the original joint line by conducting a measured-resection technique. We examined the relationships of 3D distance between the femoral head center and ankle center before and after TKA, degree of hip–knee–ankle angle (HKA) improvement, and degree of flexion contracture angle improvement. Results: All cases showed limb lengthening (average, 9.4 ± 6.0 mm). The coefficients of correlation with limb lengthening and the degree of HKA improvement and the degree of flexion contracture angle improvement were good (0.730 and 0.751, respectively). The correlation between the degree of total improvement (the degree of HKA improvement + the degree of flexion contracture angle improvement) and limb lengthening was strong (r = 0.896). Conclusion: The expected limb lengthening when performing measured-resection TKA is expressed as 0.58 × (the degree of HKA improvement + the degree of flexion contracture angle improvement) mm and is a useful index.

Clinical Results of Total Hip Arthroplasty in Two Patients with Charcot Hip Joints due to Congenital Insensivity to Pain with Anhydrosis

Traditionally, Charcot arthropathy has been considered an absolute contraindication for total hip arthroplasty (THA). However, some recent reports have shown that good short- to mid-term results can be achieved by improving the durability of the implant. This paper reports the mid- to long-term results of THA in two patients with Charcot hip joints caused by congenital insensivity to pain with anhydrosis. Both patients suffered multiple posterior dislocations in the six months immediately following surgery. However, with the continuous use of a hard abduction brace, one patient was eventually able to walk with a lofstrand cane and the other with the use of one crutch. Although one patient experienced a dislocation five years after surgery, X-rays taken after nine years and five years, respectively, revealed no clinical signs of implant loosening. We conclude that, with careful planning and appropriate precautions, THA may be a viable treatment option for Charcot hip joints caused by congenital insensivity to pain with anhydrosis.

Effectiveness and Safety of Needle Medial Collateral Ligament Pie-Crusting in Total Knee Arthroplasty: A Cadaveric Study

Abstract Medial collateral ligament (MCL) pie‐crusting technique in total knee arthroplasty (TKA) is one of the methods of medial release. The effects and risks of blade pie‐crusting have been reported in previous studies. However, only a few have reported the safety and efficacy of needle pie‐crusting. In this cadaveric study, we quantitatively evaluated the amount of gap change by MCL needle pie‐crusting. We investigated five knees of four fresh human cadavers and performed posterior‐stabilized TKA. Only deep MCL release as the medial release was conducted. We punctured the MCL from the deep layer to the superficial layer using a 18 G needle in a 90‐degree flexion position for 0, 10, 20, 50, 75, and 100 times. Medial and lateral gaps were measured accurately with a balancer at determined times in 0 and 90‐degree flexion positions. Changes in medial and lateral gaps were not significant differences in flexion and extension position. However, in 90‐degree flexion, medial gap changes were tended to be larger than lateral gap changes. A 0.6 mm additional medial release and a 0.2 mm additional lateral release were found per 10 times pie crust in flexion position (100 times, p: 0.08). However, large differences existed among the cases. Needle pie‐crusting is safer than blade pie‐crusting because of the small efficacy of one‐time pie crust. MCL needle pie‐crusting showed varied effects for each case. This result indicates the risk of relaxation of an unexpected gap. Caution should be taken when choosing between needle pie‐crusting and blade pie‐crusting.

Selection of a surgical approach for total hip arthroplasty according to the depth to the surgical site

Background The surgical depths of approaches for total hip arthroplasty (THA) have not been reported previously. In this study, we investigate the relationships between the distances to the centre of the femoral head in different approaches and body mass index (BMI). Methods The study included patients with normal hip joints who presented to our hospital. We used the pelvic coordinate system relative to the anterior pelvic plane and the femur coordinate system relative to the posterior condylar plane. We assessed the anterior, anterolateral, lateral and posterior approaches, and defined each approach line. We evaluated each distance in terms of BMI and gender. Results 164 hips were assessed. The distance to the centre of the femoral head was the longest in the posterior approach, followed by the lateral, anterolateral, and anterior approaches (p<0.05). Additionally, the distance in each approach increased as patients’ BMI increased. The approximated line tilts were almost the same. The correlation coefficients between BMI and the distance to the centre of the femoral head were high in all approaches. In the anterior and anterolateral approaches, men with low BMI had a short distance to the femoral head. The distance for each approach was measured according to the pelvic coordinate system and the femur coordinate system. The results showed no significant differences between them. Conclusions The distance to the centre of the femoral head is the shortest in the anterior approach, regardless of BMI and gender. The distance in each approach might increase with an increase in BMI. BMI has similar effects in all approaches.

Increase in safe zone area of the acetabular cup using dual mobility cups in THA.

Background Dual mobility cup (DMC) inserts reduce the risk of dislocation after total hip arthroplasty (THA). No available research has clearly delineated stability advantages of DMC inserts in primary and revision THA. We investigated: (i) the degree of change in the safe zone of the cup when a DMC insert is used compared to a fixed insert; (ii) the method of selecting candidates for a DMC insert without changing the position of the acetabular (cup) component during revision THA in frequent dislocation cases caused by implant impingement. Methods A model of the pelvis and femur was developed from computed tomography images. The safe zone was defined as the area in the acetabular component, over which conditions for stable range of motion were satisfied. The safe zone was calculated for both a fixed and a DMC insert over a predetermined range of 3-D motion, and the effect of increasing the anteversion position of the femoral component from 5° to 35° was quantified. Results The lowest ratio of the area of the safe zone was about 4.9 at 20° anteverison of the femoral component. Safe zone of DMC inserts zone had increased stability of 10°-15° in both vertical and horizontal directions, compared to fixed inserts. A 5- to10-fold expansion of the safe zone can be expected with the use of DMC insert. Conclusions DMC insert could help to set the acetabular component more accurately in primary and revision THA.

The influence of surgical approach on postoperative pelvic tilt after total hip arthroplasty

BackgroundPast reports have shown the tendency of posterior pelvic tilt to increase over time after total hip arthroplasty (THA). We have hypothesized that the volume and extent of released joint capsule may influence the change in postoperative pelvic tilt. This study was conducted to ascertain whether surgical approach during THA (posterior or anterior) has an effect on postoperative changes in pelvic tilt.MethodsWe conducted a retrospective review of 81 hips in 60 patients. Patients classified as Crowe group 2, 3, and 4, those who had multiple previous compression fractures, and those with spinal fusion due to spinal arthrosis were excluded. Also, those who had previously undergone THA or total hip resurfacing also were excluded. Patients were divided into two groups, those with preoperative anterior pelvic tilt and those with posterior tilt. Preoperative and postoperative X-rays and CT scans for each group were assessed to determine the chronological change in pelvic tilt, and the data were statistically analyzed for patients who had experienced both the posterior and anterior approaches.ResultsRegardless of surgical approach, there was no significant difference in the mean change in postoperative APP angle over time in either the bilateral or unilateral cases or in the groups of preoperative anterior or posterior pelvic tilt.ConclusionsOur results showed that surgical approach does not influence postoperative pelvic tilt after THA. In preoperative planning for THA, therefore, surgeons may need not to consider the difference of surgical approach with regard to postoperative changes in pelvic tilt.