Won Yong Shon

Mismatch between PFNa and medullary canal causing difficulty in nailing of the pertrochanteric fractures

The proximal femoral nail (PFN) and the proximal femoral nail anti-rotation (PFNA) have been successfully used in the management of osteoporotic pertrochanteric fractures. Although many studies have described the geometrical mismatch between the antecurvation of the femur and the contemporary intramedullay nails, technical difficulties related to the mismatch between the femoral bowing and the PFN/PFNA at the time of nailing have rarely been discussed in the literature. We have experienced a technical difficulty related to the mismatch between the medullary canal and the PFN/PFNA. We describe the complications related with the mismatch and the technical pitfalls and some technical tips to avoid this problem are also described.

Treatment of Femoroacetabular Impingement with Surgical Dislocation

Background The authors report the results of femoroacetabular impingement (FAI) treated with a surgical dislocation. Methods From April 2005 to May 2007, 15 FAI hips were treated with a surgical dislocation. The male/female ratio, mean age and mean symptom duration was 12/2, 35.8 years and 2.3 years, respectively. Radiographs and MR arthrograms were taken. The clinical evaluation involved changes in the pre- and postoperative Harris hip score (HHS). Results There were 12 hips (80%) with at least one structural abnormality in the radiographs, with 11 (79%) labral tears and 8 (73%) abnormally high angles in the MR arthrograms. We performed 15 osteochondroplasties, 12 labral repairs, 12 acetabuloplasty, and 3 debridements. The mean HHS improved from 76 to 93 points. Three non-unions of the trochanteric osteotomy sites were encountered as complications. Conclusions Radiographs and MR arthrograms are important for making a proper diagnosis of FAI and planning treatment. A surgical dislocation can be used to treat FAI but further technical improvements will be needed for fixation of the greater trochanteric osteotomy sites.

Validation of a simple radiographic method to determine variations in pelvic and acetabular cup sagittal plane alignment after total hip arthroplasty

Background and purposeOrientation of acetabular component, influenced by pelvic tilt, body position, and individual variations affects the outcome following total hip arthroplasty (THA). Currently available methods of evaluation are either imprecise or require advanced image processing. We analyzed intersubject and intrasubject variability of pelvic tilt, measured by sagittal sacral tilt (ST) and its relationship with acetabular component tilt (AT) by using a simple method based on standard radiographs.Materials and methodsST was measured on lateral radiographs of pelvis including lumbosacral spine obtained in supine, sitting, standing, and lateral decubitus position for 40 asymptomatic THA patients and compared to computed tomography (CT) data obtained in supine position. AT was measured on lateral radiographs (measured acetabular tilt: MAT) in each position and compared to measurement of AT on CT and an indirectly calculated AT (CAT).ResultsMean ST changed from supine to sitting, standing, and lateral decubitus positions as follows: 26.5 ± 15.5° (range 4.6–73.4°), 8.4 ± 6.2° (range 0.6–24.5°), and 13.4 ± 8.4° (range 0.1–24.2°; p < 0.0001, p = 0.002, p = 0.006). The MAT on radiographs was not significantly different from the MAT measured on CT (p = 0.002) and the CAT (p = 0.06). There is a good correlation between change in ST and MAT in sagittal plane (r = 0.93).ConclusionMeasurement of ST on radiographs is a simple and reliable method to track changes in pelvic tilt in different body positions. There is significant intersubject and intrasubject variation of ST and MAT with postural changes and it may explain causes of impingement or instability following THA, which could not be previously explained.

Pelvic osteolysis relationship to radiographs and polyethylene wear.

The relationship of radiographic pelvic osteolysis to computed tomographic (CT) volume and polyethylene wear remains controversial. We evaluated the sensitivity and specificity of radiographs in detecting osteolysis considering CT scan as the true value, in 118 hips with cementless cups. Correlation between osteolysis volume in CT, area of osteolysis in radiograph, and linear wear of polyethylene was assessed. The sensitivity and specificity of anteroposterior radiographs for detection of osteolysis was 57.6% and 92.9%, respectively. Addition of oblique radiographs increased the sensitivity to 64.4% without changing the specificity. The sensitivity increased to 92.8% for lesion more than 1000 mm(3). There was good correlation between 2-dimensional (2D) osteolytic area in radiograph and 3-dimensional (3D) volume (r = 0.74) in CT scan and linear wear of polyethylene showed good correlation with 3D CT volume (r = 0.62) and 2D area in radiograph (r = 0.60). Thus radiographs are useful to screen clinically significant osteolysis.

Can pelvic tilting be ignored in total hip arthroplasty

INTRODUCTION The orientation of acetabular component is influenced by pelvic tilt, body position and individual variation in pelvic parameters. Most post-operative adverse events may be attributed to malposition of the component in the functional position. There is evidence that orientation of the pelvis changes from the supine to standing position. Authors report a case of recurrent dislocation after total hip arthroplasty due to excessive pelvic tilting. PRESENTATION OF CASE A 69-year old female with coxarthrosis had undergone total hip replacement with recurrent dislocation of the hip on bearing weight in spite of using constrained acetabular component. DISCUSSION Our case report substantiates the influence of pelvic tilt, incurred by a sagittal deformity of spine, on dynamic orientation of the acetabular cup which was positioned in accordance with the anatomic landmarks alone. If the reference is only bony architecture and dynamic positions of the pelvis are not taken into account, improper functional orientation of the acetabular cup can result in sitting and standing positions. These can induce instability even in anatomically appropriately oriented acetabular component. CONCLUSION The sagittal position of pelvis is a key factor in impingement and dislocation after total hip arthroplasty. Pelvic tilting affects the position of acetabular component in the sagittal plane of the body as compared with its anatomic position in the pelvis. We suggest a preoperative lateral view of spine-pelvis, in upright and supine position for evaluation of a corrective adaptation of the acetabular cup accordingly with pelvic balance.

Imaging findings of femoroacetabular impingement syndrome: focusing on mixed-type impingement

The aim of our study was to analyze the imaging findings of femoroacetabular impingement (FAI). Eight consecutive patients [age range, 19-46 years (mean, 28.6 years); M/F ratio=7:1] who underwent operation for FAI were analyzed. We analyzed bump, acetabular retroversion and protrusion, and osteoarthritis in the radiographs. In MR arthrography, we analyzed alpha-angle, anterolateral labral tear, cartilage abnormality, herniation pit, paralabral cyst, subchondral cyst, and marrow edema. We correlated the imaging findings with operative findings. In the radiographs, all eight patients showed bump and osteoarthritis (Kellgren-Lawrence score II-IV), and five (62.5%) patients showed acetabular retroversion. In MR arthrography, anterolateral labral tear and mild cartilage abnormality (Outerbridge grade I and II) were seen in all eight patients; increased alpha-angle was seen in six cases (75%). Anterolateral labral tear, bump, and mild cartilage abnormality were seen in all eight patients during operation. According to the above findings, we divided the patients into three cam-type and five mixed-type FAI. In the five mixed-type FAI, both bump and acetabular retroversion were seen. The mixed-type FAI is the most prevalent type in our study. The main imaging findings of mixed-type FAI were acetabular retroversion, bump, and early osteoarthritis in radiographs, and anterolateral labral tear, cartilage abnormality, and increased alpha-angle in MR arthrography.

The Use of the Posterior Lesser Trochanter Line to Estimate Femoral Neck Version An Analysis of Computed Tomography Measurements

We hypothesized that the lesser trochanter could be a useful guide for estimating femoral component version during total hip arthroplasty. We conducted a study of 88 patients to evaluate the relationship between the posterior lesser trochanter line (PLTL) and the femoral neck axis (FNA) using computed tomographic scans. The mean angle between the PLTL and the FNA was 17.4° ± 7.1° (range, -1.6° to 36.5°). The PLTL angle correlated (r(2) = 0.67-0.72) with the FNA angle. Intraclass correlation coefficient values showed a high level of intraobserver and interobserver agreement in the angles between the PLTL and the FNA. We found a constant relationship between the lesser trochanter and the FNA, and femoral neck version can be estimated, using the PLTL, with reasonable reliability.

Incidence and Radiologic Outcome of Intraoperative Lateral Wall Fractures in OTA 31A1 and A2 Fractures Treated With Cephalomedullary Nailing.

Objectives: To determine the incidence of intraoperative lateral wall fracture in OTA 31A1 and A2 fractures treated with a cephalomedullary nail and to determine whether this contributed to the failure of treatment. Design: Retrospective review. Setting: University hospital. Patients/Participants: A cohort of 291 patients (31.A1/A2-231, A3-60) was assessed with pre- and postoperative radiographs. Patients with intact lateral wall fractures were included in the study. One hundred sixty-five of 231 patients (77%) completed radiologic follow-up. They were divided into 2 groups. Group 1 (129 patients, 78%) consisted of patients with an intact lateral wall postoperatively. Group 2 (36 patients, 22%) consisted of patients who sustained lateral wall fracture intraoperatively (FLW). Intervention: Closed reduction and intramedullary nail insertion. Main Outcome Measurements: Rate of failure/reoperation and collapse were compared between the groups. Results: The incidence of intraoperative lateral wall fracture was 21% (48 of 165). Fracture collapse and failure rate were not statistically significant in either groups (group 1: 1%, group 2: 5%). Conclusions: The incidence of intraoperative lateral wall fracture in OTA 31A1 and A2 pertrochanteric fractures after cephalomedullary nailing is similar to sliding hip screws. The presence of lateral wall fracture did not adversely affect healing of pertrochanteric fractures. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The influence of surgical factors on dislocation of the meniscal bearing after Oxford medial unicompartmental knee replacement: a case–control study

The aim of this study was to evaluate the risk factors for dislocation of the bearing after a mobile-bearing Oxford medial unicompartmental knee replacement (UKR) and to test the hypothesis that surgical factors, as measured from post-operative radiographs, are associated with its dislocation From a total of 480 UKRs performed between 2001 and 2012, in 391 patients with a mean age of 66.5 years (45 to 82) (316 female, 75 male), we identified 17 UKRs where bearing dislocation occurred. The post-operative radiological measurements of the 17 UKRs and 51 matched controls were analysed using conditional logistic regression analysis. The post-operative radiological measurements included post-operative change in limb alignment, the position of the femoral and tibial components, the resection depth of the proximal tibia, and the femoral component-posterior condyle classification. We concluded that a post-operative decrease in the posterior tibial slope relative to the pre-operative value was the only significant determinant of dislocation of the bearing after medial Oxford UKR (odds ratio 1.881; 95% confidence interval 1.272 to 2.779). A post-operative posterior tibial slope < 8.45° and a difference between the pre-operative and post-operative posterior tibial slope of > 2.19° may increase the risk of dislocation.

Minimally invasive plate osteosynthesis using a helical plate for metadiaphyseal complex fractures of the proximal humerus

Minimally invasive plate osteosynthesis (MIPO) has been used for humeral shaft fractures, but concerns exist about soft tissue injuries. The purpose of this study was to report the surgical technique and clinical outcomes of MIPO using a helical plate for metadiaphyseal complex humeral shaft fractures. Twelve patients with acute displacement involving proximal and middle third humeral shaft fractures (AO type C) were treated using the MIPO technique with a helical plate. Fracture union, complications, and functional outcomes were evaluated using the Constant-Murley score and Mayo Elbow Performance Score (MEPS) at final follow-up. All fractures united at an average of 17.9 weeks. No major complications, such as neurovascular injury, infection, and nonunion, were observed. Mean Constant-Murley and MEPS scores at final follow-up were 88.6 and 97.9, respectively. A MIPO technique using a helical plate can be a useful surgical option for metadiaphyseal complex fractures of the humeral shaft.