In primary total hip arthroplasty (THA) for patients with Crowe II or higher classes developmental dysplasia of the hip (DDH) or rapidly destructive coxopathy (RDC), the placement of the cup can be challenging due to superior and lateral acetabular bone defects. Traditionally, bone grafts from resected femoral heads were used to fill these defects, but bulk graft poses a risk of collapse, especially in DDH with hypoplastic femoral heads or in RDC where good quality bone is scarce. Recently, porous metal augments have shown promising outcomes in revision surgeries, yet reports on their efficacy in primary THA are limited. This study retrospectively evaluated 27 patients (30 hips) who underwent primary THA using cementless cups and porous titanium acetabular augments for DDH or RDC, with follow-up periods ranging from 2 to 10 years (average 4.1 years). The cohort included 22 females (24 hips) and 5 males (6 hips), with an average age of 67 years at the time of surgery. The findings at the final follow-up showed no radiographic evidence of loosening or radiolucency around the cups and augments, indicating successful biological fixation in all cases. Clinically, there was a significant improvement in the WOMAC score from an average of 39.1±14.7 preoperatively to 5.1±6.4 postoperatively. These results suggest that the use of cementless cups and porous titanium acetabular augments in primary THA for DDH and RDC can lead to high levels of clinical improvement and reliable biological fixation, indicating their potential as a viable solution for managing challenging acetabular defects in these conditions.
This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry. In total, 116 patients who underwent unilateral total hip arthroplasty were included in this study. Of these, 93 had DDH-OA and 23 had PHOA. Patients with DDH-OA were categorized into three groups: Crowe grade I, II/III, and IV. Anatomical femoral length, femoral length greater trochanter (GT), femoral length lesser trochanter (LT), tibial length, foot height, lower LL, and whole LL were evaluated using preoperative CT data of the whole leg in the supine position. Asymmetry was evaluated in the Crowe I, II/III, IV, and PHOA groups.Aims
Methods
Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined.Aims
Methods
The purposes of this study were to evaluate the accuracy and feasibility of a robotic preparation for acetabular metal augments in patients with developmental dysplasia of the hip (DDH). Mako robotic arm reaming was used in 7 DDH to prepare the bony cavities for both Trident PSL cups and Tritanium acetabular wedge augments in six hips with Crowe 2 or 3 DDH. In CT-based planning, a properly sized cup was placed in the original acetabulum, and the same sized cup was also placed to fit the superolateral acetabular defect. The coordinates of the planned positions of cup and augment were recorded to manage the robotic arm reaming. After registration of the patient's pelvis, robotic reaming was performed first for the augment, then, for the cup by changing the target position of reaming as planned. The accuracy of the cup and augment placement was assessed on postoperative CT. To evaluate the feasibility of the robotic procedure, the OR time and blood loss were compared with those of 13 patients who received the same cup and augment systems with a conventional technique. All procedures were done without fracture or fixation failure. There were no differences in OR time or blood loss between the two procedures. Postoperative CT measurements of the distance between the cup center and the augment sphere center showed less than 2mm difference from the Mako preoperative planning. Although a longer time of follow up evaluation is mandatory, our robotic acetabular augment preparation technique is accurate and feasible.
Acetabular revision surgery is challenging due to severe bone defects. Burch-Schneider anti-protrusion cages (BS cage: Zimmer-Biomet) is one of the options for acetabular revision, however higher dislocation rate was reported. A computed tomography (CT)-based navigation system indicates us the planned direction for implantation of a cemented acetabular cup during surgery. A large diameter femoral head is also expected to reduce the dislocation rate. The purpose of this study is to investigate short-term results of BS cage in acetabular revision surgery combined with the CT-based navigation system and the use of large diameter femoral head. Sixteen hips of fifteen patients who underwent revision THA using allografts and BS cage between September 2013 and December 2017 were included in this study with the follow-up of 2.7 (0.1–5.0) years. There were 12 women and three men with a mean age of 78.6 years (range, 59–61 years). The cause of acetabular revision was aseptic loosening in all hips. The failed acetabular cup was carefully removed, and acetabular bone defect was graded using the Paprosky classification. Structural allografts were morselized and packed for all medial or contained defects. In some cases, solid allograft was implanted for segmental defects. BS cage was molded to optimize stability and congruity to the acetabulum and fixed with 6.5 mm titanium screws to the iliac bone. The inferior flange was slotted into the ischium. The upside-down trial cup was attached to a straight handle cup positioner with instrumental tracker (Figure 1) and placed on the rim of the BS cage to confirm the direction of the target angle for cement cup implantation under the CT-based navigation system (Stryker). After removing the cement spacer around the X3 RimFit cup (Stryker) onto the BS cage for available maximum large femoral head, the cement cup was implanted with confirming the direction of targeting angle. Japanese Orthopedic Association score (JOA score) of the hip was used for clinical assessment. Implant position, loosening, and consolidation of allograft were assessed using anterior and lateral radiographies of the pelvis.Introduction
Methods
Robotic-assisted hip arthroplasty helps acetabular preparation and implantation with the assistance of a robotic arm. A computed tomography (CT)-based navigation system is also helpful for acetabular preparation and implantation, however, there is no report to compare these methods. The purpose of this study is to compare the acetabular cup position between the assistance of the robotic arm and the CT-based navigation system in total hip arthroplasty for patients with osteoarthritis secondary to developmental dysplasia of the hip. We studied 31 hips of 28 patients who underwent the robotic-assisted hip arthroplasty (MAKO group) between August 2018 and March 2019 and 119 hips of 112 patients who received THA under CT-based navigation (CT-navi group) between September 2015 and November 2018. The preoperative diagnosis of all patients was osteoarthritis secondary to developmental dysplasia of the hip. They received the same cementless cup (Trident, Stryker). Robotic-assisted hip arthroplasty were performed by four surgeons while THA under CT-based navigation were performed by single senior surgeon. Target angle was 40 degree of radiological cup inclination (RI) and 15 degree of radiological cup anteversion (RA) in all patients. Propensity score matching was used to match the patients by gender, age, weight, height, BMI, and surgical approach in the two groups and 30 patients in each group were included in this study. Postoperative cup position was assessed using postoperative anterior-posterior pelvic radiograph by the Lewinnek's methods. The differences between target and postoperative cup position were investigated.Introduction
Methods
The anatomic abnormalities are observed in developmental dysplasia of the hip (DDH) and it is challenging to perform the total hip arthroplasty (THA) for some DDH patients. If acetabular cup was placed at the original acetabular position in patients with high hip dislocation, it may be difficult to perform reduction of hip prosthesis because of soft tissue contracture. The procedures resolving this problem were to use femoral shortening osteotomy, or to place the acetabular cup at a higher cup position than the original hip center. Femoral shortening osteotomy has some concerns about its complicated procedure, time consuming, and risk of non-union. Conversely, implantation of the acetabular cup at the higher cup position may eliminate these shortcomings and this procedure is considered to be preferred if possible. However, the criteria of cases without femoral shortening osteotomy are not clear. In this study, we retrospectively analysed the clinical outcomes of patients performed THAs for high hip dislocation, and clarified the adaptation of THA with or without femoral shortening osteotomy. We included a total of 65 hip joints from 57 patients who underwent primary THA using Modulus stem for high hip dislocation from November 2007 to December 2015 at our institution. The mean follow up period was 5.2 years (2 – 10 years). The mean age at surgery was 65.4 years (Table 1). Thirty seven hips were classified as Crowe III, and twenty eight hips as Crowe IV based on Crowe classification. We classified patients into two groups based on the use of femoral osteotomy. Then, we compared the surgical time, blood loss, Japanese Orthopaedic Association (JOA) Score as clinical outcomes, preoperative position of the greater trochanter, the cup position, and complications between two groups. The position of the greater trochanter was measured the height of the tip of greater trochanter from the inter teardrop line. The cup center position was assessed by measuring the distance between the cup center and ipsilateral tear drop. Receiver operating characteristic (ROC) curves were plotted for deciding the cut-off value for the height of the greater trochanter. The cut-off value presented the maximum sensitivity and specificity was determined.Introduction
Methods
The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors. We enrolled 90 patients (82 female, eight male) with DDH showing unilateral OA changes, and 43 healthy volunteers (26 female, 17 male) as controls. The mean age was 61.8 years (39 to 93) for the DDH groups, and 71.2 years (57 to 84) for the control group. Using a CT-based coordinate measurement system, we evaluated the following vertical distances: top of the greater trochanter to the knee centre (femoral length GT), most medial prominence of the lesser trochanter to the knee centre (femoral length LT), and top of the greater trochanter to the medial prominence of the lesser trochanter (intertrochanteric distance), along with assessments of femoral neck anteversion and neck shaft angle.Aims
Patients and Methods
The purpose of this study was to compare two different types
of metal-on-metal (MoM) bearing for total hip arthroplasty (THA):
one with a large femoral head (38 mm to 52 mm) and the other with
a conventional femoral head (28 mm or 32 mm). We compared clinical
outcome, blood metal ion levels, and the incidence of pseudotumour in
the two groups. Between December 2009 and December 2011, 62 patients underwent
MoM THA with a large femoral head (Magnum group) and 57 patients
an MoM THA with a conventional femoral head (conventional group).
Clinical outcome was assessed using the Harris Hip score, University
of California, Los Angeles (UCLA) activity score and EuroQol-5D
(EQ-5D). Blood metal ion levels were measured and MRI scans were
analyzed at a minimum of five years postoperatively.Aims
Patients and Methods
To obtain appropriate joint gap and soft tissue balance, and to correct the lower limb alignment are important factor to achieve success of total knee arthroplasty (TKA). A variety of computer-assisted navigation systems have been developed to implant the component accurately during TKA. Although, the effects of the navigation system on the joint gap and soft tissue balance are unclear. The purpose of the present study was to investigate the influence of accelerometer-based portable navigation system on the intraoperative joint gap and soft tissue balance. Between March 2014 and March 2015, 36 consecutive primary TKAs were performed using a mobile-bearing posterior stabilized (PS) TKA (Vanguard RP; Biomet) for varus osteoarthritis. Of the 36 knees, 26 knees using the accelerometer-based portable computer navigation system (KneeAlign2; OrthAlign) (N group), and 10 knees using conventional alignment guide (femur side; intramedullary rod, tibia side; extramedullary guide) (C group). The intraoperative joint gap and soft tissue balance were measured using tensor device throughout a full range of motion (0°, 30°, 45°, 60°, 90°, 120°and full flexion) at 120N of distraction force. The postoperative component coronal alignment was measured with standing anteroposterior hip-to-ankle radiographs.INTRODUCTION
METHODS
The concept of anatomical stam is fit-and-fill in the proximity of the femur and to expect wall fixation, following to reduce thigh pain and stress shielding. Although the femoral medullary form and size are different in each races. CentPillar TMZF stem (stryker ®) is anatomical stem designed based on computer-tomography of Japanese femurs. The purpose of this study was to evaluate clinical and radiographic outcomes of CentPillar TMZF stem at a mean of 3.6 years postoperatively. We asseses the results of 98 primary total hip arthroplasty (THA) performed using a CentPillar TMZF stem in 91 Japanese patients (4 males, 94 females) undergoing surgery between August 2007 and June 2011, the mean age at the time of surgery was 62.0 (41–81) years old. The Diagnosis were osteoarthritis (OA) in 91 hips, rapidly destructive coxopathy (RDC) in 4 hips, rheumatoid arthritis (RA) in 3 hips. Clinical and radiographic assessments were performed for every patient for every follow up using Japan Orthopaedic Association (JOA) Score, thigh pain, revision surgery and complications. Radiographic assessments were including stem alignment on anteroposterior radiograph, stress shielding, bone remodeling, radiolucent line, osteolysis, loosening and subsidence.INTRODUCTION
METHODS
The Taperloc Microplasty stem design was based on that of the Taperloc stem with flat tapered wedge and the distal portion of the Taperloc stem was shortened by 35mm. We report the minimum two-year follow up (mean, 26 months) of 68 primary total hip arthroplasty using the Taperloc Microplasty stem. 39 Magnum acetabular cups and 29 M2a Taper acetabular cups were inserted with metal on metal articulation. The series comprised 67 patients (20 men, 47 women) with a mean age at operation of 65 years (31 to 85). The principal diagnosis was osteosrthritis. Their mean JOA Hip Score improved significantly from 36 points preoperatively to 96 points at two-year follow up. Radiological asseement showed good bony stability in all implants. There was one case of post operative anterior dislocation. We did not see intra-operative fracture previously reported for this implant. There were no clinical and radiological complications related to MOM articulation. This short-term follow up study demonstrates that the clinical outcome of the Tapeloc Microplasty stem is comparable with that of standard Taperloc stem and other flat taper wedge stems.
Modulus femoral prosthesis is a modular cementless femoral system which consists of 5 degree tapered conical stem made of a titanium alloy with 8 fins of 1mm and modular neck. Modular neck enables to control any ideal stem anteversion as a surgeon prefers. This system is considered to be useful in severe hip deformity, for example developmental dysplasia of the hip (DDH). In this study, clinical and radiographic outcomes of the Modulus femoral prosthesis were evaluated at a mean of 3.6 (2–6) years postoperatively. We assessed the results of 193 primary total hip arthroplasty using a Modulus femoral prosthesis in 169 patients (15 males, 154 females) undergoing surgery between September 2007 and December 2011. The mean age at the time of surgery was 65.6 (31–86) years old. The diagnoses were osteoarthritis (OA) in 178 hips (including 167 hips of DDH), rapidly destructive coxopathy (RDC) in 6 hips, rheumatoid arthritis (RA) in 6 hips, osteonecrosis in 2 hips, and subchondral insufficiency fracture in one hip. Clinical outcomes were assessed using Japan Orthopedic Association (JOA) hip scores and complications. Radiographic assessments were including stem alignment, bone on-growth, cortical hypertrophy, stress shielding and stem subsidence. 43.8 points of the preoperative mean JOA score was significantly improved to 93.1 points postoperatively. In one case intraoperative femoral fracture was occurred. One dislocation had occurred and thigh pain was observed in one hip. No revision surgery was required. In 192 hips of 193 hips (99.5%), stem was implanted in neutral position (within ±2 degrees). Bone on-growth was observed in all cases (94.3% in zone 3; 73.1% in zone 5; 30.6% in zone 2; 22.3% in zone 6). Cortical hypertrophy was observed in 66 hips (34.2%) at zone 3 and 5. Reduction of bone density due to stress shielding was observed (1st degree was 58.5%; 2nd degree was 29.5%; 3rd degree was 11.9%; 4th degree was 0%). In 22 cases (11.4%), more than 2mm of stem subsidence was observed, however the subsidence was stopped within 6 months in all cases. Modulus femoral prosthesis showed good clinical results and radiographic findings up to 6 years postoperatively.
Metal on metal total hip arthroplasty (MoM THA) provides the potential improvement in articular wear. However, several adverse events including pseudotumor had been reported. Magnetic resonance imaging (MRI) was considered to be the proposal tool for detection of pseudotumor after MoM THA. In this study, we performed the screening of pseudotumor after MoM THA using the MRI. We studied 43 patients with M2a Magnum® (Biomet) and 34 patients with M2a Taper® (Biomet) of MoM THA from December 2009 to December 2011 with follow-up of 2.5 years (2.0–4.0 years) after surgery. MRI assessments were performed at a mean of 2.1 years postoperatively. Pseudotumor findings were graded using Anderson classification (Skeletal Radiol, 2011: 40; 303). Age, sex, height, weight, Harris Hip Score, EQ5D satisfaction score, UCLA activity score, and blood metal ion levels were evaluated. The prevalence of pseudotumor was 27.2%; 56 normal (Type A), 13 mild (C1), 8 moderate (C2) and none were graded severe (C3). Weight and BMI in the mild group was significantly higher than those in normal. There was no significant difference in age, sex and height among these groups. With regard to Harris Hip score, pain and ROM score in moderate group was significantly lower than that in normal and mild group. EQ5D satisfaction score and UCLA activity score showed not significant differences among groups. 3.01±3.32 μg/L of blood cobalt ion levels in the moderate groups was significantly higher than 0.97±0.64 μg/L in normal group. Blood cobalt ion levels of 1 mild and 2 moderate were over the threshold of 7 μg/L. These patients were implanted with M2a Taper, not M2a Magnum. 14% of the prevalence in the patients with M2a Magnum was significantly lower than 41% in the patients with M2a Taper. No revision surgeries were required. The patients with no pseudotumor did not show the increase of blood metal ion. Contrarily, several patients showed the increase of blood metal ion in case of detecting pseudotumor. MRI assessments were useful for screening of pseudotumor after MoM THA and blood metal ion should be investigated for patients with mild and moderate pseudotumor in MoM THA.
Metal on metal total hip arthroplasty provides the potential improvement in articular wear and the use of large-diameter femoral heads following the prospect for reduction in the risk of dislocation. The purpose of this study was to compare the clinical and radiographic outcomes as well as serum metal ion level between the two different component designs with small and large femoral heads in metal on metal total hip arthroplasty. We studied 39 patients with large head (Magnum®, Biomet; cup size minus 6 mm) and 37 patients with small head (M2a taper®, Biomet; 28 or 32 mm head) of metal on metal total hip arthroplasty between December 2009 to October 2011 with follow-up of 2.1 years (1.0–3.3 years) after surgery. Harris Hip Score, UCLA activity score, EQ-5D, radiographic assessment, and serum cobalt and chromium ion levels were evaluated. Harris Hip Score, UCLA activity score, and EQ-5D were improved after surgery in small and large head groups, however, no significant differences were observed between both groups. Cup inclination was below 50 degree in all prosthesis. No loosening and no osteolysis were observed. Cobalt and chromium ion was not detected before surgery; however, metal ion levels of both groups were increased after surgery in time dependent manner. There was no significant difference between two groups at one year after surgery. One patient in each group showed the increase of cobalt ion level over 7 ppb (15.4 ppb, 12.9 ppb) without any clinical symptom including pain. Cup inclination was 29 degree in both patients and cup anteversion was 38 and 41 degree, respectively. There was no significant difference of ion levels between both groups. No dislocation was observed in large head group while one dislocation occurred in small head group. No patients required the revision surgery. This metal on metal component, especially with large femoral heads, showed the good clinical results at the maximum follow up of 3.3 year after surgery. However, the ion level of two patients increased over 7 ppb and longer follow-up will be needed.
