Recent advances in the direct anterior approach to total hip arthroplasty: a surgeon's perspective.

INTRODUCTION: The direct anterior approach (DAA) has its origins in the first and oldest approach for hip replacement in the literature, but at the same time it would not be fanciful to suggest its increasing popularity as the latest approach for hip replacement procedures, especially among younger surgeons. However, in a geographical context, the DAA is not considered the major approach in most countries. Moreover, the term DAA encompasses numerous variations in terms of technique. AREAS COVERED: In this narrative review, we describe our recent experience of advances in the DAA in terms of improved techniques and devices, along with some of its disadvantages. Also, we express our perspective on its future application. EXPERT OPINIONS: The DAA is established as one of exemplary approaches to THA. The use of fluoroscopy, the traction table, and appropriate soft tissue management has become essential in the DAA for a safe and trouble-free procedure with adequate patient comfort. With the combination of recent technologies such as robotics, three-dimensional preoperative planning, and artificial intelligence (AI)-based surgeon assist systems, we can look forward to the DAA being performed more efficiently in the future.

Yields of mesenchymal stromal cells from synovial fluid reflect those from synovium in patients with rheumatoid arthritis.

The yield of primary synovial mesenchymal stromal cells (MSCs) from synovium of patients with rheumatoid arthritis (RA) is highly variable, but cell transplantation therapy with autologous synovial MSCs requires accurate prediction of the synovial MSC yield per synovium weight. Here, we determined whether the yield of synovial fluid MSCs might predict the ultimate yield of primary MSCs from the synovium of RA knees. Synovial fluid and synovium were harvested during total knee arthroplasty from the knee joints of 10 patients with RA. Synovial fluid (1.5 mL) was diluted fourfold and plated equally into six 60 cm2 dishes. Nucleated cells from digested synovium were similarly plated at 1 × 104 cells in 6 dishes. All dishes were cultured for 14 days and analyzed for MSC yields and properties, including in vitro chondrogenesis. The cultured synovial cell number was correlated with the cultured synovial fluid cell number (n = 10, R2 = 0.64, p < 0.01). Synovial fluid cells formed cell colonies and showed MSC-like surface epitopes and multi-differentiation potential. However, the cartilage pellet weight indicated a greater chondrogenic potential of the synovial MSCs (n = 8). The primary MSC yields from synovial fluid and synovium were correlated, indicating that the synovial fluid MSC yield can predict the ultimate synovial MSC yield.

Does total hip arthroplasty via the direct anterior approach using dual mobility increase leg length discrepancy compared with single mobility?

BACKGROUND: Total hip arthroplasty (THA) via the direct anterior approach (DAA) using dual mobility cup (DMC) is considered to effectively prevent postoperative dislocation. However, the dislocation and reduction procedure using a trial implant during the surgery is difficult because of high soft tissue tension. Thereby, leg length discrepancy (LLD) is difficult to assess when using DM via the DAA. PURPOSE: To compare the LLD between cases using conventional SM and those using DMC in THA via the DAA with fluoroscopy. PATIENTS AND METHODS: We retrospectively investigated 34 hips treated with DMC (DMC-DAA group) and 31 hips treated with SM (SM-DAA group). The LLD was defined as the difference in the distance from the teardrop to the medial-most point of the lesser trochanter between the operative and nonoperative sides at immediate postoperative X-ray. RESULTS: The mean LLD in the DMC-DAA group and SM-DAA group was 0.68 ± 7.7 mm and 0.80 ± 5.5, respectively, with no significant difference. The absolute value of the LLD in the DMC-DAA group and SM-DAA group was 6.3 ± 4.4 mm and 5.9 ± 5.5, respectively, with no significant difference. CONCLUSION: Despite the difficulty in assessment of the LLD during THA via the DAA using DMC, this technique does not increase the LLD compared with the use of SM. LEVEL OF EVIDENCE: III, matched case-control study.

Autograft-prosthesis composite use for a Vancouver type B1 periprosthetic femur fracture with pelvic acetabular component migration after bipolar hemiarthroplasty: A case report.

INTRODUCTION: Bipolar hemiarthroplasty (BHA) is a commonly performed procedure for elderly patients with an intra-capsular fracture of the femoral neck. However, surgeons performing BHA worry about the rate of acetabular wear, and acetabular prosthesis protrusion can pose a challenging surgical problem. The number of periprosthetic femur fractures is expected to increase. Generally, well-fixed stems require open reduction and internal fixation (ORIF), whereas loose stems require revision arthroplasty. CASE REPORT: A 68-year-old Asian woman was admitted to our hospital. She had sustained a left displaced femoral neck fracture at the age of 58 years. BHA was performed via a posterior approach in another hospital. Ten years later, she presented with severe left hip pain following a low-energy fall. A radiograph of the hip joint demonstrated a Vancouver type B1 periprosthetic femur fracture with severe acetabular prosthetic protrusion. Single-stage reconstructive surgery was performed. A transgluteal approach was used, with distal extension to the fracture site of the femur. Acetabular reconstruction was performed using a Kerboull-type plate in combination with massive allografts for the large bone defects of the acetabulum. Regarding the femoral side, the proximal bone fragment and cementless stem that had been fixed were longitudinally opened with an osteotomy and separated. After that, the stem was changed to a cemented long stem and combined with the prior proximal bone fragments using cement and wires in an allograft-prosthesis composite technique (autograft-prosthesis composite). CONCLUSION: Although the standard treatment for Vancouver type B1 periprosthetic femur fractures is ORIF, it would have been difficult to reconstruct the hip joint solely with osteosynthesis because the femur was severely shortened by marked migration of the BHA. Single-stage reconstructive surgery using an autograft-prosthesis composite was effective treatment for a Vancouver type B1 periprosthetic femur fracture with concomitant severe acetabular prosthetic protrusion after BHA.

Posterior versus direct anterior approach in total hip arthroplasty: difference in patient-reported outcomes measured with the Forgotten Joint Score-12.

INTRODUCTION: When the postoperative outcome of primary total hip arthroplasty (THA) was compared with the direct anterior approach (DAA) and the posterior approach (PA), there was no significant difference of the clinical outcome at 6 months to 1 year after surgery in many studies. This study was performed to compare the medium-term outcome of THA via the DAA or PA and clarify which approach achieves better quality of life (QOL). METHODS: We investigated 61 hips receiving primary THA (30 via DAA and 31 via PA), using hip function scores such as the Harris Hip Score (HHS) and patient-reported outcomes such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), and the Forgotten Joint Score-12 (FJS). RESULTS: The mean duration of postoperative follow-up was 36.8 months in the DAA group and 40.5 months in the PA group. There was no difference in preoperative or postoperative HHS between the two groups. Although there was no difference of postoperative WOMAC and JHEQ, the postoperative FJS-12 score was significantly higher in the DAA group than in the PA group (75.2 ± 15.9 versus 60.1 ± 24.4, p = 0.01). CONCLUSION: When forgetting the artificial joint in daily life is the target, better QOL can be achieved by performing THA via the DAA.

Comparison of mesenchymal stem cells obtained by suspended culture of synovium from patients with rheumatoid arthritis and osteoarthritis.

BACKGROUND: Mobilization of mesenchymal stem cells (MSCs) from the synovium was revealed using a "suspended synovium culture model" of osteoarthritis (OA). The pathology of rheumatoid arthritis (RA) differs from that of OA. We investigated whether mobilization of MSCs from the synovium also occurred in RA, and we compared the properties of synovial MSCs collected from suspended synovium culture models of RA and OA. METHODS: Human synovium was harvested during total knee arthroplasty from the knee joints of patients with RA (n = 8) and OA (n = 6). The synovium was suspended in a bottle containing culture medium and a culture dish at the bottom. Cells were harvested from the dish and analyzed. RESULTS: No significant difference was observed between RA and OA in the harvested cell numbers per g of synovium. However, the variation in the number of cells harvested from each donor was greater for RA than for OA. The harvested cells were multipotent and no difference was observed in the cartilage pellet weight between RA and OA. The surface epitopes of the cells in RA and OA were similar to those of MSCs. CONCLUSION: Mobilization of MSCs from the synovium was demonstrated using a suspended synovium culture model for RA. The harvested cell numbers, chondrogenic potentials, and surface epitope profiles were comparable between the RA and OA models.

The Baba classification focused on implant designs is useful in setting the therapeutic strategy for interprosthetic femoral fracture.

PURPOSE: The purpose of this study was to investigate the clinical outcomes of femoral fracture with implants on the proximal and distal sides to verify whether actual fracture morphologies follow the fracture types of Baba classification focusing on implant designs useful for periprosthetic femoral fracture. METHODS: Prosthesis was present in 85 with periprosthetic femoral fractures. Excluding 73 patients with fracture around the femoral stem or fracture of the TKA femoral component alone, 12 patients with 14 legs with both implants were investigated. All patients were radiographically assessed for implant stability according to the Baba classification. For clinical evaluation, intra- and postoperative complications, the operation time, and intra-operative blood loss were investigated. RESULTS: The Baba classification fracture type showed the implant as unstable and stable types in 3 and 11 legs, respectively. The consistency rate between the Baba classification-based judgment of plain radiograms acquired at the time of injury and actual surgical findings was 100%. As a result of treatment according to the Baba classification, bone union was achieved in all patients. There were no intra- or postoperative complications. CONCLUSIONS: Applying the Baba classification, implant stability could be sufficiently evaluated in not only periprosthetic femoral fractures following hip arthroplasty, but also interprosthetic femoral fractures, thereby verifying its usefulness in setting the treatment strategy.

Total hip arthroplasty via the direct anterior approach with a dual mobility cup for displaced femoral neck fracture in patients with a high risk of dislocation.

INTRODUCTION: Although total hip arthroplasty (THA) is superior to bipolar hemiarthroplasty (BHA) for displaced femoral neck fracture in terms of hip pain, function and reoperation rate, THA has a higher rate of dislocation. The direct anterior approach (DAA) and a dual mobility cup (DMC) are associated with lower rates of dislocation. The aim of this study was to investigate the outcomes of THA compared with BHA, and in those patients who had a THA we investigated those with a DMC (DMC-THA) and compared them with those had a single conventional cup (Single cup-THA). MATERIALS: A total of 89 patients living independently were included between 2009 and 2015. We assessed patient characteristics, peri- and post-operative outcomes, walking ability and one-year mortality. Adjusted odds ratios (Adjusted ORs) were estimated for decrease of walking ability and one-year mortality using a logistic regression model with adjustment for potential confounders such as age, neuromuscular diseases with weakness, duration of surgery, perioperative blood loss and preoperative walking ability. RESULTS: BHA (20 patients) versus THA (69 patients): There was no significant difference in the walking ability in either group. Multivariable logistic regression analysis demonstrated a significant association with one-year mortality in both groups [THA Adjusted ORs 0.088 (95% CI 0.0007-0.69); p = 0.020]. Single cup-THA (36 patients) versus DMC-THA (33 patients): The DMC-THA group had significantly greater age and more patients with neuromuscular diseases with weakness compared with the Single cup-THA group. Multivariable logistic regression analysis demonstrated no significant difference in the decrease of walking ability and in the one-year mortality between the groups. There were no post operative dislocations in any group. DISCUSSION: THA via the DAA is one of the best treatments for displaced femoral neck fracture with a low risk of dislocation. THA via the DAA with a DMC is a safe and effective treatment for the patients with a high risk of dislocation.

Safe and Effective Reduction Technique for Intertrochanteric Fracture with Ipsilateral Below-Knee Amputated Limb.

The positioning of the patient on the fracture table is critical for the successful reduction and operative fixation of intertrochanteric hip fractures. However, this manipulation is challenging with patients who have undergone amputations of their legs. A 97-year-old man presented to the emergency department with symptom of right hip pain following a mechanical fall. He had a below-knee amputation on his right leg following a traffic accident as a 19-year-old and had a below-knee patellar tendon bearing prosthesis fitted to his lower limb for mobility. Radiographs of his pelvis revealed a displaced intertrochanteric fracture of the right side femur. The patient was positioned on a fracture table, as in the standard procedure. The method of inverting the traction boot to accommodate the flexed knee and stump described by Al-Harthy could be used to provide traction and rotational control. Internal fixation was performed using a short femoral nail. Postoperatively, the patient could walk with full weight bearing using a prosthesis on his affected limb. The method of inverting the traction boot to accommodate the flexed knee and stump can be used safely and effectively to achieve and maintain fracture reduction during fixation of intertrochanteric fractures for patients with a below-knee amputated limb.

Yields and chondrogenic potential of primary synovial mesenchymal stem cells are comparable between rheumatoid arthritis and osteoarthritis patients.

BACKGROUND: Mesenchymal stem cells derived from the synovial membrane (synovial MSCs) are a candidate cell source for regenerative medicine of cartilage and menisci due to their high chondrogenic ability. Regenerative medicine can be expected for RA patients with the inflammation well-controlled as well as OA patients and transplantation of synovial MSCs would also be a possible therapeutic treatment. Some properties of synovial MSCs vary dependent on the diseases patients have, and whether or not the pathological condition of RA affects the chondrogenesis of synovial MSCs remains controversial. The purpose of this study was to compare the properties of primary synovial MSCs between RA and OA patients. METHODS: Human synovial tissue was harvested during total knee arthroplasty from the knee joints of eight patients with RA and OA respectively. Synovial nucleated cells were cultured for 14 days. Total cell yields, surface markers, and differentiation potentials were analyzed for primary synovial MSCs. RESULTS: Nucleated cell number per 1 mg synovium was 8.4 ± 3.9 thousand in RA and 8.0 ± 0.9 thousand in OA. Total cell number after 14-day culture/1 mg synovium was 0.7 ± 0.4 million in RA and 0.5 ± 0.3 million in OA, showing no significant difference between in RA and OA. Cells after 14-day culture were mostly positive for CD44, CD73, CD90, CD105, negative for CD45 both in RA and OA. There was no significant difference for the cartilage pellet weight and sGAG content per pellet between in RA and OA. Both oil red O-positive colony rate and alizarin red-positive colony rate were similar in RA and OA. CONCLUSIONS: Yields, surface markers and chondrogenic potential of primary synovial MSCs in RA were comparable to those in OA. Synovium derived from RA patients can be the cell source of MSCs for cartilage and meniscus regeneration.

Long-term results of rotational acetabular osteotomy for osteonecrosis with collapse of the femoral head in young patients.

PURPOSE: The surgical treatment of osteonecrosis with collapse of the femoral head is still controversial. The purpose of this study was to investigate the clinical outcome of rotational acetabular osteotomy by Ninomiya and Tagawa for osteonecrosis of the femoral head in young patients. PATIENTS AND METHODS: Rotational acetabular osteotomy was performed in 202 consecutive patients between 1995 and 2003. Among them, rotational acetabular osteotomy with osteonecrosis of the femoral head was performed in 31 patients (42 hips). The mean age at the time of surgery was 31.2 years (range 16-45). The mean duration of follow-up was 16.1 years (range 13.1-21 years). RESULTS: The mean preoperative Japanese Orthopedic Association hip score of 56.8 points improved to a mean of 72.4 points at the final follow-up. The 10-year survival rate with conversion to total hip arthroplasty as an end-point was 91.9%, and the 15-year survival rate was 75.5%, the 20-year survival rate was 67.9%. The conversion to total hip arthroplasty was performed in nine hips. The average time to the conversion to total hip arthroplasty was 12.1 years. CONCLUSIONS: Even though the necrotized range is wide, if normal cartilage remains on the lateral side of the femoral head, it can be utilized for the weight-bearing region by laterally rotating the acetabulum. Since the outcome was favorable, we believe that this is a valuable treatment option for this disease.

Influence of the contralateral hip state after total hip arthroplasty on patient-reported outcomes measured with the Forgotten Joint Score-12.

PURPOSE: The purpose of this study was to examine the influence of the contralateral hip state on postoperative assessment using the Forgotten Joint Score-12 (FJS-12) in comparison with the McMaster Universities Osteoarthritis Index (WOMAC) and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). METHODS: One hundred and thirty-four hips underwent total hip arthroplasty (THA) between 2014 and 2015. Of these, the subjects were 106 hips with degenerative hip arthrosis as a primary disease for whom initial THA was performed on the affected side. The WOMAC and JHEQ were investigated before surgery and 1 month, 6 months, and 1 year after surgery. The FJS-12 was examined 1 month, 6 months, and 1 year after surgery. RESULTS: We divided the subjects into three groups based on the state of the contralateral hip, which was not surgically treated in this study: healthy (n = 43), THA (n = 31), and OA (n = 31) groups. One year after surgery, the mean FJS-12 scores in the healthy, THA, and OA groups were 69.1, 52.8, and 68.0 points, respectively. In the THA group, the score was significantly lower than in the healthy and OA group. There were no significant differences in WOMAC and JHEQ scores among the three groups. CONCLUSIONS: The FJS-12 score in the presence of an arthroplasty on the contralateral side was more markedly influenced by the contralateral hip state compared with that in the presence of contralateral painful OA. This result suggests that it is necessary to understand the characteristics of PROs and utilize them for post-THA assessment.

Kerboull-type plate in a direct anterior approach for severe bone defects at primary total hip arthroplasty: technical note.

INTRODUCTION: For cases with extensive acetabular bone defects, we perform surgery combining the Kerboull-type (KT) plate and bone graft through direct anterior approach (DAA) in primary total hip arthroplasty (THA) requiring acetabular reconstruction as minimally invasive surgery. This paper provides the details of the surgical procedure. METHODS: The basic structure of the Kerboull-type plate is a cruciform plate. Since the hook of the Kerboull-type plate has to be applied to the tear drop, a space for it was exposed. The tear drop is located in the anterior lower region in surgery through DAA in supine position. It was also confirmed by fluoroscopy as needed. The bone grafting was performed using an auto- or allogeneic femoral head for bone defects in the weight-bearing region of the hip joint. RESULTS: Of 563 patients who underwent primary THA between 2012 and 2014, THA using the KT plate through DAA was performed in 21 patients (3.7%). The mean duration of postoperative follow-up was 31.8 months. The mean operative time was 188.4 min, and the mean blood loss was 770 g. The patients became able to walk independently after 2.4 days on average (1-4 days). On clinical evaluation, the modified Harris Hip Score was 45.6 ± 12.4 before surgery, and it was significantly improved to 85.3 ± 8.97 on the final follow-up. DISCUSSION: DAA is a true intermuscular approach capable of conserving soft tissue. Since it is applied in a supine position, fluoroscopy can be readily used, and it was very useful to accurately place the plate.

Total hip arthroplasty via the direct anterior approach with Kerboull-type acetabular reinforcement device for an elderly female with factor XI deficiency.

We present a case of successful and uncomplicated total hip arthroplasty with an acetabular reinforcement device in an elderly patient with hip osteoarthritis already diagnosed with factor XI deficiency, which is a very rare bleeding disorder and at high risk of post-operative haemorrhage, and it poses a substantial challenge to surgeons as a consequence of the specific risks of infection and fixation failure. Moreover, bone fragility in elderly patient increases potential risk of adverse event. Fresh frozen plasma was used to supplement factor XI activity. Importantly, transfusion-transmitted disease such as having factor XI inhibitor was promptly surveyed prior to the supplement since the patient had previous history of the administration of fresh frozen plasma. Under prompt and effective peri-operative haemostasis, rigid implant fixation and rigorous attention to the prevention of infection seem to achieve the best possible outcomes for elderly patients with a bleeding disorder undergoing total hip arthroplasty.

Sagittal spinopelvic alignment predicts hip function after total hip arthroplasty.

The aim of this study was to investigate the association between preoperative sagittal spinopelvic alignment and postoperative clinical outcomes after total hip arthroplasty (THA). This retrospective study included 92 patients with hip osteoarthritis who underwent primary THA between May 2013 and October 2015. Patients' characteristics, radiographic sagittal spinopelvic parameters and modified Harris Hip Scores, including function scores (gait scores and functional activities scores), were investigated. Multivariate linear regression analysis was performed to determine the associations between each preoperative sagittal spinopelvic parameter and postoperative hip function The preoperative sagittal spinopelvic parameters that were associated with postoperative gait scores were sagittal vertical axis (adjusted ß-coefficient=-0.28, P=0.02), lumbar lordosis angle (adjusted ß-coefficient=0.29, P=0.0089), pelvic tilt (adjusted ß-coefficient=-0.25, P=0.045), sacral slope (adjusted ß-coefficient=0.27, P=0.017) and pelvic incidence minus lumbar lordosis angle (adjusted ß-coefficient=-0.31, P=0.01). The preoperative sagittal spinopelvic parameters that were related to the postoperative functional activities scores were sagittal vertical axis (adjusted ß-coefficient=-0.38, P=0.0051) and pelvic incidence minus lumbar lordosis angle (adjusted ß-coefficient=-0.39, P=0.0033). Patients with preoperative imbalanced sagittal alignment such as larger sagittal vertical axis, larger pelvic incidence minus lumbar lordosis and retroversion of pelvis had poorer clinical outcomes than others after THA. While, those preoperative imbalanced patients with anteversion of pelvis may have a compensatory ability which could correct the abnormal sagittal alignment after THA. Preoperative sagittal spinopelvic alignment affected postoperative clinical outcomes after THA.

In total hip arthroplasty via the direct anterior approach, a dual-mobility cup prevents dislocation as effectively in hip fracture as in osteoarthritis.

PURPOSE: The main purpose of this study was to compare the outcome of total hip arthroplasty (THA) via the direct anterior approach (DAA) using a dual-mobility cup (DMC) in patients with femoral neck fracture to those in patients undergoing elective THA for osteoarthritis. PATIENTS AND METHODS: We retrospectively investigated 40 hips with femoral neck fracture (group A), and 81 hips with osteoarthritis (group B). THA via the DAA using the DMC was performed in both groups. A primary/secondary outcome variable were the presence of dislocation/operative time, intra- and/or peri-operative complication, and mortality. RESULTS: Dislocation did not occur in either group. The complication rate was slightly higher in group A than in group B, but not statistically significant. CONCLUSION: THA with the DMC using the DAA was as effective for femoral neck facture as it was for elective THA in patients with osteoarthritis.

Total Hip Arthroplasty for Implant Rupture after Surgery for Atypical Subtrochanteric Femoral Fracture.

Treatment methods for delayed union and nonunion of atypical femoral fracture are still controversial. Moreover, no treatment method has been established for implant rupture caused by delayed union and nonunion. We encountered a 74-year-old female in whom nonunion-induced implant rupture occurred after treatment of atypical subtrochanteric femoral fracture with internal fixation using a long femoral nail. It was unlikely that sufficient fixation could be obtained by repeating osteosynthesis alone. Moreover, the patient was elderly and early weight-bearing activity was essential for early recovery of ADL. Based on these reasons, we selected one-stage surgery with total hip arthroplasty and osteosynthesis with inverted condylar locking plate as salvage procedures. Bone union was achieved at 6 months after surgery. This case illustrated that osteosynthesis-combined one-staged total hip arthroplasty could be considered as one of the options for nonunion-induced implant rupture of atypical femoral subtrochanteric fracture.

Benefit and risk in short term after total hip arthroplasty by direct anterior approach combined with dual mobility cup.

PURPOSE: No previous reports have described the benefits and risks associated with the dual mobility cup (DMC) in primary THA via direct anterior approach (DAA). The aim of this study was to compare the safety and rate of early postoperative complication of the DAA with the DMC for THA with those of the DAA with a single standard cup, and to investigate the influence of the learning curve of the use of DMC on intra- and perioperative outcomes. METHODS: We retrospectively investigated 60 hips treated in the single-DAA group and 60 hips treated in the dual-DAA group. A primary/secondary outcome variable was the presence of any intra- or perioperative complication within the first 6 months/the operative time and hip function at 6 months postoperatively. We also analyzed influence of the learning curve of the use of DMC on intra- and perioperative outcomes. RESULTS: No intraoperative complications were observed in either group. One anterior dislocation and one periprosthetic hip fracture were occurred in the single-DAA group. The surgical times in the single-DAA and dual-DAA groups were 112.0 ± 20.9 and 121.0 ± 26.9 min (p < 0.001). There was no significant difference in the 6-month postoperative hip function scores between the two groups. There was no influence of the learning curve of the use of DMC on intra- and perioperative outcomes. CONCLUSION: We have demonstrated the short-term safety and lack of inferiority of using the DMC in the DAA compared with the standard single mobility cup.

Greater trochanter chip fractures in the direct anterior approach for total hip arthroplasty.

BACKGROUND: The direct anterior approach (DAA) for the treatment of total hip arthroplasty (THA) has gained popularity in recent years. Chip fractures of the greater trochanter are frequently seen, but the risk factors for such fractures are unknown. The study aimed to identify the risk factors for chip fractures in patients undergoing primary THA by the DAA during the surgeons' learning curve. MATERIALS AND METHODS: From November 2011 to April 2015, the first experiences of three surgeons who performed 120 THAs by the DAA (120 hips; 40 cases per beginner surgeon) were included. The incidence of chip fracture of the greater trochanter, the size of the greater trochanter as measured by computed tomography, and the patients' characteristics were retrospectively investigated. RESULTS: After exclusion of 11 hips, the remaining 109 hips were investigated. Chip fracture of the greater trochanter was identified in 32 hips (29.4 %). Univariate analysis with and without fractures showed that the width and depth of the greater trochanter were statistically significant risk factors (p = 0.02 and p < 0.001, respectively). Multivariate analysis using a logistic regression model demonstrated that the depth of the greater trochanter was an independent risk factor for chip fracture of the greater trochanter (OR 1.725; 95 % CI 1.367-2.177; p < 0.001). CONCLUSION: The size of the greater trochanter was identified as a risk factor for chip fracture of the greater trochanter. Novice surgeons should pay attention to the size of the greater trochanter when performing THA by the DAA.

Safety in early experience with a direct anterior approach using fluoroscopic guidance with manual leg control for primary total hip arthroplasty: a consecutive one hundred and twenty case series.

BACKGROUND AND PURPOSE: An encouraging result with direct anterior approach (DAA) is attractive for both patients and surgeons. However, the risks associated with beginning to use DAA require further analysis of the learning curve and better countermeasures to ensure safety. We ask whether the complication rate in the DAA by the inexperienced surgeon could be decreased with specific countermeasures. Our hypothesis was that the complication rate would be low even in early phase of the learning curve using the DAA with these particular countermeasures. PATIENTS AND METHODS: We investigated a consecutive series of 120 primary THA using the DAA with four specific countermeasures; 1) defined exclusion criteria for DAA; 2) no positioning table; 3) use of fluoroscopy as much as required; and 4) having an experienced assistant for DAA (one who has performed the procedure in more than 100 cases). The operative time, the time of fluoroscopic use during the operation, intra and post-operative complications, re-operation for any reason, and cup and stem alignment were investigated. RESULTS: Although the operation times were similar, the duration of fluoroscopy decreased with surgeons' experience. There were no intra-operative complications and no re-operations for any reason. One anterior dislocation was observed in one patient. The mean cup inclination and anteversion angle was 39.7° ± 7.6° and 30.3° ± 7.6°; 43.3 % of stems were positioned in flexion, 55.8 % in the neutral position on the lateral view. CONCLUSION: We demonstrated a lower complication rate during our early experience with the DAA using four countermeasures. Using these countermeasures for the first 40 cases may be useful for surgeons who are considering DAA.