Combined use of beta-tricalcium phosphate with different porosities can accelerate bone remodelling in open-wedge high tibial osteotomy.

Background/Objective: Beta-tricalcium phosphate (ß-TCP) is often used as a gap filler in open-wedge high tibial osteotomy (OWHTO). The aim of the present study was to investigate the effects of using ß-TCP with different porosities on bone remodelling after OWHTO.Methods: We evaluated 29 knees in 26 patients that underwent OWHTO using ß-TCP with porosities of 60% and 75% (combined group). A further 30 knees in 28 patients that underwent OWHTO using ß-TCP with 60% porosity alone were allocated as a control group. In the combined group, a ß-TCP block with 75% porosity was inserted into the gap at the cancellous bone site and a ß-TCP block with 60% porosity was inserted into the medial cortical bone side. In the control group, a ß-TCP block with 60% porosity was inserted into the osteotomy gap. The bone remodelling phases of the inserted ß-TCP blocks were evaluated on standard anteroposterior radiographs using the modified van Hemert classification at 3 and 6 months post-operatively. Results: The rate of satisfactory bone remodelling at the cancellous bone sites was 86.2% (25/29) in the combined group and 0% (0/30) in the control group at 3 months post-operatively (p<0.05), progressing to 96.6% (28/29) in the combined group and 20% (6/30) in the control group at 6 months post-operatively (p<0.05). Conclusion: The present study demonstrated that combined use of ß-TCP with high and low porosities can significantly enhance bone formation. The combined use of artificial bones with different porosities is useful for early bone remodelling in OWHTO.

The short external rotators dissection during the posterior approach in total hip arthroplasty did not change the blood flow.

OBJECTIVES: The posterior approach in total hip arthroplasty (THA) often requires dissection of the short external rotators (SERs), which could increase the postoperative dislocation rate. The reattachment of the dissected SERs has been reported to reduce the dislocation rate, while such repair generally causes progression of muscle atrophy. 1 of the suggested causes of atrophy is reduced blood flow to the repaired SERs. The present study aimed to measure the blood flow of the SERs before dissection (pre-tenotomy) and after reattachment (post-reattachment) during the posterior approach in THA. METHODS: This prospective study included 26 patients who underwent THA via the posterior approach. A laser-Doppler rheometer was used to measure the blood flow in the following SERs at the time of pre-tenotomy and post-reattachment: the piriformis muscle (PM), superior gemellus (SG), inferior gemellus (IG), obturator internus (OI), and subcutaneous tissue as a control. RESULTS: The average pre-tenotomy and post-reattachment blood flows (mL/minutes/100 g) were: 1.90 ± 0.28 and 1.92 ± 0.40 in the PM, 1.94 ± 0.20 and 1.99 ± 0.39 in the SG, 1.91 ± 0.21 and 1.94 ± 0.30 in the IG, 1.93 ± 0.22 and 1.98 ± 0.36 in the OI, and 1.94 ± 0.24 and 1.87 ± 0.38 in the subcutaneous tissue. The pre-tenotomy and post-reattachment blood flows did not show significant difference in any muscle. CONCLUSIONS: Laser-Doppler blood flow measurements showed that the blood flow is preserved, even when the SERs are dissected and reattached in THA via the posterior approach.

Effects of lateral circumflex femoral artery ligation on blood flow to the surrounding muscles in the direct anterior approach.

BACKGROUND: The direct anterior approach to the hip joint enables the identification and ligation of the lateral circumflex femoral artery. However, the effect of lateral circumflex femoral artery ligation on blood flow to the muscles surrounding the hip remains unknown. This study clarified the changes in blood flow to the surrounding muscles following ascending branch ligation of this artery. METHODS: We included 36 consecutive patients (8 male and 28 female) who underwent total hip arthroplasty via the direct anterior approach for hip osteoarthritis between April 2015 and July 2016. The intraoperative blood flow to the tensor fascia latae (TFL), vastus lateralis (VL), rectus femoris (RF), and subcutaneous tissue (control) was measured using a laser Doppler blood flow meter. Measurements were repeated after artery ligation and at the end of surgery. We compared the means (±SD) of these measurements at each location and time point. RESULTS: The patients' mean age was 64.2 ± 9.0 years, systolic and diastolic blood pressures were 92.8 ± 13.6 and 54.9 ± 9.1 mmHg, respectively, and body mass index was 23.1 ± 3.9 kg/m2. Hypertension was noted in 35.9% patients and dyslipidemia in 27.8%. The mean surgical duration was 101 (70-158) min. The preligation blood flow in TFL, VL, RF, and subcutaneous tissue was 3.91 ± 1.93, 5.15 ± 2.19, 4.51 ± 2.24, and 3.03 ± 0.99 mL/min/100 g, respectively. CONCLUSIONS: Blood flow to TFL significantly decreased post ligation and at the end of surgery. However, there was no change in blood flow to VL and RF.

Motor-Evoked Potential Analysis of Femoral Nerve Status During the Direct Anterior Approach for Total Hip Arthroplasty.

BACKGROUND: During the direct anterior approach for total hip arthroplasty, a retractor is placed on the anterior wall of the acetabulum to retract the iliopsoas muscle. This step with the retractor has been reported to put the patient at risk for femoral nerve damage. The present study aimed to clarify the effects of the anterior acetabular retractor on the status of the femoral nerve during the direct anterior approach on the basis of transcranial motor-evoked potential (MEP) analysis. METHODS: Between July 2016 and February 2017, 22 patients underwent primary total hip arthroplasty via the direct anterior approach with MEP analysis. The integrity of the femoral nerve was tested at 3 time points: preoperatively, as a control (first period); just after retractor placement on the anterior wall of the acetabulum (second period); and after the procedure (third period). The association between operative time and femoral nerve status was examined. Postoperative femoral nerve damage was determined by the presence of causalgia and the results of a manual muscle test (MMT) for strength of knee extension. RESULTS: The mean amplitude of the femoral nerve was significantly reduced, from 100% in the first period to 54% (range, 5% to 100%) in the second period (p < 0.01), but then significantly improved to 77% (range, 20% to 100%) in the third period (p < 0.01). In 17 (77%) of the 22 patients, the amplitude of the femoral nerve in the second period was reduced, while only 5 patients (23%) showed no reduction. The mean operative time was 83 minutes (range, 63 to 104 minutes), and no significant correlation was observed between operative time and improvement of femoral nerve status between the second and third periods (p = 0.83 and r = -0.05). All 22 patients had a postoperative MMT grade of 5 for knee extension without causalgia of the femoral nerve. CONCLUSIONS: On the basis of the MEP analysis, 17 (77%) of the 22 patients showed a significant reduction of the femoral nerve amplitude despite careful placement of the retractor on the anterior wall of the acetabulum. Although this reduction appears reversible, placement of an anterior retractor should be performed with careful attention to the femoral nerve. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Incidence of delayed union one year after peri-acetabular osteotomy based on computed tomography.

BACKGROUND: Pubic bone nonunion and delayed union are reported as post-operative complications after peri-acetabular osteotomy (PAO). However, few studies have determined the incidence of delayed union using computed tomography (CT) scans. This study aimed to determine the incidence of delayed union at one year after PAO using X-ray and CT scans. METHODS: We performed a retrospective review of 150 hips in 132 consecutive patients with acetabular dysplasia who underwent PAO between January 2012 and June 2016 and evaluated 107 hips for which pelvic CT scans taken at one year after PAO were available. Clinical evaluations included age at surgery, weight, body mass index (BMI) and history. Radiographic evaluations were to assess pubic, ischial and iliac delayed union at one year post-operatively. RESULTS: Based on X-ray analysis, the incidence of delayed union in the pubic, ischial and iliac bones was 11.2% (12 hips), 5.6% (6 hips) and 0% (0 hips), respectively, and20.6% (22 hips), 8.4% (9 hips) and 0% (0 hips), respectively, based on CT scans. CONCLUSION: The incidence of delayed union of the pubis and ischium at one year after PAO according to CT scans was higher than that based on X-ray imaging. CT scans are useful in patients with some symptoms at the osteotomy site. LEVEL OF EVIDENCE: Level III.

Three-dimensional computed tomography analysis on bony birth canal after bilateral periacetabular osteotomy.

BACKGROUND: Curved periacetabular osteotomy (CPO) is one of the joint preserving procedures for developmental dysplasia of the hip. CPO requires osteotomy of the medial wall of the acetabulum, which may cause narrowing of the bony birth canal and this step may result in increased risk of cesarean delivery. We analyzed the narrowest part of the bony birth canal using three-dimensional computed tomography (3D-CT) before and after bilateral CPO. METHODS: Between February 2007 and March 2014, there were 29 cases of bilateral CPO in which both pre- and post-operative 3D-CT were available. Transverse diameters of the pelvic inlet, contraction, outlet, expansion, and teardrop were analyzed. Among them, the narrowest part of the bony birth canal was investigated, which being smaller than the normal lower threshold value for vaginal delivery (95 mm) was considered as a risk for cesarean delivery. RESULTS: The transverse diameters of both pelvic expansion and teardrop significantly decreased after CPO (both p < 0.01), while other diameters showed no significant changes. Among these two diameters, the narrowest diameter of the bony birth canal was the pelvic teardrop in all 29 cases. That in 24 patients (82.8%) was greater than 95 mm, while that in five patients (17.2%) showed less than 95 mm. CONCLUSIONS: Based on 3D-CT analysis, the narrowest part of the bony birth canal after bilateral CPO was the pelvic teardrop. In this study, 82.8% of the patients showed pelvic teardrop diameter greater than 95 mm, while that of the other patients (17.2%) were less than 95 mm.

The Utility of False-Profile Radiographs for the Detection of Osteoarthritis Progression in Acetabular Dysplasia.

BACKGROUND: Both the lateral center-edge angle and acetabular roof obliquity on anteroposterior radiographs are well-known prognostic predictors of osteoarthritis progression in patients with acetabular dysplasia. However, few studies have evaluated osteoarthritis progression on false-profile radiographs. In the present study, osteoarthritis progression was evaluated on anteroposterior and false-profile radiographs. METHODS: We retrospectively evaluated 76 patients with acetabular dysplasia with Tönnis grade-0 or 1 osteoarthritis, from a group of 179 patients (209 hips), who had undergone unilateral periacetabular osteotomy from 1995 to 2005. We evaluated the hip joint of the contralateral, untreated side. All patients were followed for ≥10 years. Of the 76 patients, 52 patients with Tönnis grade-0 or 1 osteoarthritis at the latest follow-up were categorized into the non-progression group and the remaining 24 patients with Tönnis grade-2 or 3 osteoarthritis were categorized into the progression group. We evaluated patient characteristics as well as radiographic parameters, including the preoperative lateral center-edge angle, acetabular roof obliquity, and anterior center-edge angle. RESULTS: The mean duration of follow-up was 12.6 years (range, 10 to 19 years). On univariate analysis, body weight, body mass index, and all radiographic parameters indicating the severity of acetabular dysplasia significantly differed between the 2 groups. On multivariate analysis, both the anterior center-edge angle and acetabular roof obliquity were considered to be significant predictive factors for osteoarthritis progression. On receiver operating characteristic curve analysis, the cutoff values for the lateral center-edge angle, acetabular roof obliquity, and anterior center-edge angle were 15.5°, 15.5°, and 12.5°, respectively. CONCLUSIONS: In addition to the lateral center-edge angle and acetabular roof obliquity, we showed that the anterior center-edge angle is a possible prognostic predictor of osteoarthritis progression. These findings indicate that radiographic parameters based on the false-profile view are relevant. Additionally, patients with an anterior center-edge angle of ≤12.5° and a lateral center-edge angle of ≤15.5° seem to be at higher risk of osteoarthritis progression over a 10-year period. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.