Hip Center Of Rotation Research Articles

Mid-term and long-term results of restoring rotation center in revision hip arthroplasty

BackgroundTo restore rotation center exactly in revision hip arthroplasty is technically challenging, especially in Paprosky type III. The technical difficulty is attributable to the complicated acetabular bone defect. In this study, we discussed the method of restoring rotation center in revision hip arthroplasty and reported the clinical and radiological outcome of mid-term and long-term follow-up.MethodsThis study retrospectively reviewed 45 patients (48 hips) who underwent revision hip arthroplasty, in which 35 cases (35 hips) were available for complete follow-up data. During the operation, the acetabular bone defect was reconstructed by impaction morselized bone graft, and the hip rotation center was restored by using remnant Harris fossa and acetabular notches as the marks. The clinical outcome was assessed using the Harris hip score. Pelvis plain x-ray was used to assess implant migration, stability of implants, and incorporation of the bone graft to host bone.ResultThe average follow-up duration was 97.60 months (range 72–168 months). The average Harris hip score improved from 29.54 ± 10.87 preoperatively to 83.77 ± 5.78 at the last follow-up. The vertical distance of hip rotation center measured on pelvis x-ray was restored to normal, with the mean distance (15.24 ± 1.31) mm (range 12.4~17.3 mm). The mean loss of vertical distance of hip rotation center was (2.21 ± 0.72) mm (range 1.1 ~ 5.3 mm) at the last follow-up.ConclusionSatisfactory clinical and radiological outcome can be obtained through restoring hip rotation center by using remnant Harris fossa and acetabular notches as the anatomical marks in revision hip arthroplasty.

Reconstruction of Paprosky type IIIB acetabular bone defects using a cup-on-cup technique: A surgical technique and case series.

Paprosky type IIIB acetabular bone defects are very difficult to reconstruct. For severe defects, we developed our own cup-on-cup technique. We defined the tantalum metal (TM) revision shell with the peripheral titanium ring removed as a TM-cup augment and the cementless hemispherical acetabulum component combined with a TM-cup augment as the cup-on-cup technique. To report the short-term results of patients with type IIIB acetabular bone defects reconstructed using the cup-on-cup technique. We retrospectively reviewed six patients (six hips) with a mean age of 59 years who underwent acetabular reconstruction using our cup-on-cup technique between January 2015 and January 2017. All acetabular bone defects were classified as type IIIB without pelvic discontinuity using the system of Paprosky. All patients were followed both clinically and radiographically for a mean duration of 42 mo. The mean Harris hip score improved from 32.4 pre-operatively to 80.7 at the last follow-up. The mean vertical position of the hip rotation centre changed from 60.9 mm pre-operatively to 31.7 mm post-operatively, and the mean horizontal position changed from 33.6 mm pre-operatively to 38.9 mm post-operatively. Greater trochanteric migration after extended trochanteric osteotomy occurred in one of six hips at 3 mo. There was no evidence of component migration at the last follow-up. The short-term results suggest that our cup-on-cup technique could be considered an effective management option for Paprosky type IIIB acetabular bone defects without pelvic discontinuity.

A 3D printed positioner for hip rotation center used in total hip arthroplasty

Objective To evaluate the application of a 3D printed positioner for hip rotation center in total hip arthroplasty. Methods From August 2015 to December 2017, 14 patients were treated by unilateral total hip arthroplasty at Department Ⅰ of Joint Surgery, Orthopaedics Hospital of Zhengzhou for avascular necrosis of femoral head or femoral neck fracture. They were 8 males and 6 females with an average age of 51.8 years (from 37 to 65 years). All their surgeries were assisted by a 3D printed positioner for hip rotation center. Postoperatively, the abduction and anteversion of acetabular cup and the hip rotation center were measured, the agreement between the hip rotation center of the affected side (O2) and the anatomical rotation center of the healthy side (O1) was assessed, and the function of the affected hip and complications were recorded at the last follow-up. Results The 14 patients were followed up for an average of 18 months (from 6 to 24 months). The postoperative ordinates of O2 and O1 were respectively 19.36 mm±3.61 mm and 18.33 mm±3.41 mm while their abscissas 39.93 mm±2.97 mm and 39.99 mm±3.16 mm, indicating agreement between O2 and O1 (P>0.05). The postoperative abduction and anteversion of the cup were within a normal range (39.3°±3.2°and 14.6°±1.2°, respectively). The last follow-up showed that their preoperative Harris hip scores (42.3±3.2) were significantly improved (94.3±4.7) (t=2.873, P=0.002) and that 13 cases were rated as excellent and one as good. X-ray follow-up showed good position of their acetabular prostheses, no loosening of the cups or femoral prostheses, and no heterotopic ossification. Conclusion A 3D printed positioner for hip rotation center can effectively assist reconstruction of the hip rotation center and accurate implantation of acetabular prosthesis in total hip arthroplasty. Key words: Arthroplasty, replacement, hip; 3D printing techniques; Center of rotation; Positioner

Short- and mid-term effectiveness of impaction bone allograft with acetabular components in treatment of severe acetabular defects

To investigate the short- and mid-term effectiveness of revision hip arthroplasty by using impaction bone allograft and acetabular components in treatment of severe acetabular defects. A clinical data of 42 patients (44 hips) with severe acetabular defects between February 2011 and May 2018 were retrospectively analyzed. All patients underwent revision hip arthroplasty by using impaction bone allograft and acetabular components. Cemented cup (24 cases, 24 hips) and non-cemented cup (18 cases, 20 hips) were used in the revision surgery. There were 17 males and 25 females with an average age of 62.8 years (range, 22-84 years). The interval between the first total hip arthroplasty and revision was 2.5-12.0 years (mean, 8.3 years). The patients were accepted revision surgery for prosthesis aseptic loosening in 32 hips (31 cases) and the periprosthetic infection in 12 hips (11 cases). Twenty-nine hips (28 cases) were Paprosky type ⅢA and 15 hips (14 cases) were type ⅢB. The preoperative Harris score was 22.25±10.31 and the height of hip rotation center was (3.67±0.63) cm and the length difference of lower limbs was (3.41±0.64) cm. The operation time was 130-245 minutes (mean, 186 minutes) and the intraoperative blood loss was 600-2 400 mL (mean, 840 mL). The postoperative drainage volume was 250-1 450 mL (mean, 556 mL). Superficial infection of the incision occurred in 1 case, and the incisions healed by first intention in the other patients. All patients were followed up 6-87 months, with an average of 48.6 months. At last follow-up, the Harris score was 85.85±9.31, which was significantly different from the preoperative score ( t=18.563, P=0.000). Imaging examination revealed that the allogeneic bone gradually fused with the host bone, and no obvious bone resorption was observed. At last follow-up, the height of the hip rotation center was (1.01±0.21) cm, which was significantly different from the preoperative level ( t=17.549, P=0.000); the length difference of lower limbs was (0.62±0.51) cm, which was significantly different from the preoperative level ( t=14.211, P=0.000). The Harris score in the cemented group and non-cemented group increased significantly at last follow-up. The height of the hip rotation center decreased, and the hip rotation centers of both groups were within the Ranawat triangle zone. The length difference of the lower limbs also decreased, and the differences in all indexes were significant between pre- and post-operation ( P<0.05). There was significant difference in the height of the hip rotation center between groups ( t=2.095, P=0.042), but there was no significant difference in the Harris score and the length difference of lower limbs between groups ( P>0.05). For severe acetabular defect (Paprosky type Ⅲ), the hip can be reconstructed with the impaction bone allograft and cemented or non-cemented components in revision hip arthroplsty. The short- and mid-term effectiveness are satisfactory.

Ten-year results of 55 dysplasia hips of hip offset and leg length reconstruction in total hip arthroplasty with cementless tapered stems having a high offset option designed for dysplastic femur.

In developmental dysplasia of the hip (DDH), the centers of hip rotation move in the superior and lateral direction. In total hip arthroplasty for such cases, movement of the center of hip rotation is in the inferior and medial direction. It causes an increase in leg length and a decrease in acetabular offset. We therefore evaluated the change of hip offset and leg length before and after surgery with two stems having a high offset option. The preoperative diagnosis was secondary osteoarthritis due to DDH excluded Crowe IV. A stem selection was decided based on preoperative two-dimensional templating. Total 55 hips in 50 patients were followed up for minimum 10 years. Pre- and postoperative clinical evaluations were performed using a hip joint function scoring system. Radiographic evaluations were used for offset and leg length measurements and other associated factors. Both stems showed excellent clinical results. A high offset option was used in 60% of all cases. No postoperative dislocations were observed. The biological fixation was stable in all cases. The hip offset was restored without excessive leg lengthening in most cases. Anatomical consistency could be maintained by using a stem which matched geometry of the proximal part and had offset option. These cementless tapered stems having a high offset option are suitable for Crowe I to III hip dysplasia if two-dimensional X-ray templates fit the shape of the proximal femurs. They were associated with excellent clinical results and biological fixation. The offset option may be useful to adjust leg length and offset in DDH patients.

Using Tantalum Augments for Major Acetabular Bone Defects in Revision Hip Surgery

Abstract Aim. The purpose of the study was to follow up the clinical and functional results of the patients with major acetabular bone defects in revision hip surgery. Materials and methods. The study was retrospective, over a period of six years (from January 2014 to January 2019), and included all the patients with hip replacement, with major acetabular bone defects, who needed Tantalum blocks substitution. 11 patients were included in the study (8 men and 3 women). The average age was 71 years (between 64 and 78 years old). The average follow up period was 23 months (between 11 and 36 months). Paprosky radiological classification was used for the preoperatory evaluation of the bone defects. In 9 cases, the bone defect was of type 2B Paprosky and in 2 cases, of type 3A. Harris score was determined preoperatory and postoperatory for the appreciation of functional results. Results. 6 patients were underwent replacement for coxarthrosis secondary to dysplasia, 2 patients for coxarthrosis secondary to aseptic necrosis and 3 patients for primary coxarthrosis. The average time elapsed from the moment of primary arthroplasty to the need of revision surgery was on average of 13 years (between 7 and 16 years). The postoperatory radiological evaluation showed an improvement of the hip rotation center from an average postoperative vertical position of 3.1 cm (between 1.2 and 4.6 cm) at an average postoperatory position of 1.1 cm (between 0.5 and 2.3). The average result of Harris score postoperatively was 36 (between 39 and 96). During the follow up period, no early loosening, infection or prosthesis dislocation was registered. Conclusions. The Tantalum Augments used in major acetabular bone defects in revision surgery represent a good option, correcting the hip rotation center, thus considerably improving the functional score.

The current role of robotics in total hip arthroplasty.

Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA.Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA.Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA.Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness.Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088

How to restore rotation center in total hip arthroplasty for developmental dysplasia of the hip by recognizing the pathomorphology of acetabulum and Harris fossa?

PurposeTo restore rotation center exactly in total hip arthroplasty (THA) is technically challenging for patients with end-stage osteoarthritis due to developmental dysplasia of the hip (DDH). The technical difficulty is attributable to the complex acetabular changes. In this study, we investigated the pathomorphology of acetabulum and Harris fossa of Crowe types I to IV and discussed the method of restoring rotation center of the hip.MethodsThis study retrospectively reviewed 56 patients (59 hips) who underwent cementless THA due to end-stage osteoarthritis of DDH. The pathomorphology of acetabulum and Harris fossa was observed during operations. Using the preoperative and postoperative pelvic radiographs, the vertical and the horizontal distances of hip rotation center were measured in order to evaluate the effects of restoring rotation center of the hip.ResultsAdult DDH acetabulum could be classified into four basic pathological types which include the shallow cup shape, the dish shape, the shell shape, and the triangular shape. Adult DDH Harris fossa could be classified into four pathological types, including the crack shape, the closed shape, the triangle shape, and the shallow shape, in accordance with the osteophyte coverage. The vertical and horizontal distances of hip rotation center on the pelvic radiographs before and after operations were as follows: the preoperative vertical distance of hip rotation center was (39.96 ± 5.65) mm, and the postoperative one was (13.83 ± 2.66) mm; the preoperative horizontal distance of hip rotation center was (42.15 ± 6.42) mm, and the postoperative one was (28.12 ± 4.56) mm.ConclusionsThe acetabulum and Harris fossa can display different pathological types on account of different degrees of dislocation and osteophyte hyperplasia in the end-stage osteoarthritis of adult DDH. The hip rotation center can be accurately restored by locating the acetabular center with Harris fossa and acetabular notch as the marks.

Bilateral High Hip Center Provides Gait Parameters Similar to Anatomical Reconstruction: A Gait Analysis Study in Hip Replacement Patients With Bilateral Developmental Dysplasia

BackgroundTotal hip arthroplasty in severe dysplasia is challenging due to diminished periacetabular bone stock and the highly placed femoral head. Although anatomical reconstruction of the hip, with required interventions such as subtrochanteric osteotomy and graft usage, is the main aim of the procedure, good long-term clinical outcomes of the high hip center technique have also been reported. Information regarding the effect of hip center placement on gait characteristics is limited; therefore, the aim of this study is to analyze the differences in gait parameters between the high hip center technique and anatomical reconstruction of the hip. MethodsTwenty patients (40 hips) with bilateral Crowe type III-IV developmental dysplasia of the hip who underwent bilateral total hip arthroplasty and completed at least 2 years of follow-up were included. Group 1 comprised 10 patients (20 hips) who underwent anatomical hip center reconstruction, while group 2 comprised 10 patients (20 hips) who underwent high hip center reconstruction. The gait characteristics of patients were examined through markers placed in certain anatomical regions, the cameras placed around, and the force plates embedded in the walking platform. ResultsThere was no significant difference in the gait characteristics according to the location of the hip rotation center. The mean temporospatial, kinematic, and kinetic values were similar between the groups. The most prominent difference was in the peak dynamic hip extension, which was lower in group 2 (−9.71° ± 7.46°) compared to group 1 (−6.80° ± 11.44°), although it was not statistically significant (P = .09). ConclusionThe bilateral high hip center technique can provide similar gait characteristics as anatomical reconstruction and may be preferred in particularly difficult cases based on the surgeon’s decision.

Total hip arthroplasty with rectangular stems and subtrochanteric transverse shortening osteotomy in Crowe type IV hips: a retrospective study

BackgroundThe complexity of femoral and acetabular anatomy and restoring anatomic center of hip rotation in Crowe type IV developmental dysplasia of the hip (DDH) complicates standard reconstruction. The aim of this study is to evaluate surgical techniques and clinical outcomes of subtrochanteric transverse shortening osteotomy with the use of cementless rectangular cross-section femoral implants in Crowe IV dysplastic hips.MethodsA total of 26 hips of 25 consecutive patients with Crowe type IV DDH who underwent cementless total hip arthroplasty with subtrochanteric femoral transverse shortening osteotomy were retrospectively analyzed. The Harris Hip Score, Visual Analog Scale-pain, leg length discrepancy, and vertical and lateral migration of hip rotation center were recorded.ResultsMean age, follow-up, and time of union were 41 ± 9.7 years, 7.1 ± 1.2 years, and 3.7 ± 1.1 months, respectively. Mean Harris Hip Score significantly improved from 38 ± 5.7 to 86 ± 6.1 points postoperatively (P < .01). Mean leg length discrepancy and Visual Analog Scale significantly decreased from 4.3 ± 1.3 to 1.2 ± 0.6 cm, and 6.4 ± 1.2 to 1.8 ± 0.8 points, respectively (P < .01). One female patient had a dislocation due to acetabular liner wear, which was managed by liner and head change. One patient had Sudeck’s atrophy, while another had pain on the lateral thigh, both of which were resolved with conservative management.ConclusionsCombined transverse subtrochanteric femoral osteotomy and cementless total hip arthroplasty with rectangular cross-section femoral implants is technically demanding, effective, and safe in femoral shortening for treatment of Crowe type IV DDH.

Mid-Term Outcomes of Revision Hip Arthroplasty with Acetabular Augments

Acetabular defects are a major obstacle to achieving good outcomes after revision hip arthroplasty. One way to deal with this problem is to use acetabular augments. We aimed to describe mid-term outcomes of revision hip arthroplasty using acetabular augments.Materials and methods. We analyzed 85 cases (83 patients) of revision hip arthroplasty using acetabular augments performed during 2012-2018 period: 53 women and 30 men with average age of 57±13 years (25-79). Distribution of acetabular defects was: 51 cases — Paprosky IIIA, 17 cases — Paprosky IIIB, 12 cases — Paprosky IIB, 5 cases — Paprosky IIC. 14 patients had chronic pelvic discontinuity. Aseptic loosening was indication for the operation in 83 cases, periprosthetic hip fracture — 1, dislocation — 1. The amount of previously undregone ipsilateral hipsurgeries was 1 in 35 cases, 2 in 25 cases, 3 and more in 25 cases. Average follow-up period was 38±19 months (1-79).Results. The average HHS score improved from 37±7 preoperatively to 73±9 after 3 months and to 80±11 after 12 months postoperatively (p = 0.001). Average VAS score improved from 7±2 preoperatively to 4±1 after 3 months and to 3±1 after 12 months postoperatively (p = 0.001). Stable acetabular fixation was achieved in each case according to X-ray findings at final follow-up. However, radiolucent lines were present around the cup in 10 cases (11.8 %) followed by no clinical evidence of aseptic loosening. Hip center of rotation was restored from 26.40±18.38 mm (4-75) preoperatively to 4.78±5.02 mm (0-20) postoperatively relatively to 0 point. Complications manifested in 9 out of 85 cases (10,6%). Distribution of complications was: periprosthetic joint infection in 6 cases, recurrent dislocation — 2, periprosthetic hip fracture — 1.7 patients required implant removal and exchange.Conclusions. Good mid-term outcomes can be achieved using acetabular augments during hip revision surgery in setting of acetabular defects. Acetabular augments are a reliable option in case of Paprosky IIIB, IIIA defects and chronic pelvic discontinuity, providing good mechanical stability.

Mid-Term Outcomes of Revision Hip Arthroplasty with Acetabular Augments

Acetabular defects are a major obstacle to achieving good outcomes after revision hip arthroplasty. One way to deal with this problem is to use acetabular augments. We aimed to describe mid-term outcomes of revision hip arthroplasty using acetabular augments.Materials and methods. We analyzed 85 cases (83 patients) of revision hip arthroplasty using acetabular augments performed during 2012-2018 period: 53 women and 30 men with average age of 57±13 years (25-79). Distribution of acetabular defects was: 51 cases — Paprosky IIIA, 17 cases — Paprosky IIIB, 12 cases — Paprosky IIB, 5 cases — Paprosky IIC. 14 patients had chronic pelvic discontinuity. Aseptic loosening was indication for the operation in 83 cases, periprosthetic hip fracture — 1, dislocation — 1. The amount of previously undregone ipsilateral hipsurgeries was 1 in 35 cases, 2 in 25 cases, 3 and more in 25 cases. Average follow-up period was 38±19 months (1-79).Results. The average HHS score improved from 37±7 preoperatively to 73±9 after 3 months and to 80±11 after 12 months postoperatively (p = 0.001). Average VAS score improved from 7±2 preoperatively to 4±1 after 3 months and to 3±1 after 12 months postoperatively (p = 0.001). Stable acetabular fixation was achieved in each case according to X-ray findings at final follow-up. However, radiolucent lines were present around the cup in 10 cases (11.8 %) followed by no clinical evidence of aseptic loosening. Hip center of rotation was restored from 26.40±18.38 mm (4-75) preoperatively to 4.78±5.02 mm (0-20) postoperatively relatively to 0 point. Complications manifested in 9 out of 85 cases (10,6%). Distribution of complications was: periprosthetic joint infection in 6 cases, recurrent dislocation — 2, periprosthetic hip fracture — 1.7 patients required implant removal and exchange.Conclusions. Good mid-term outcomes can be achieved using acetabular augments during hip revision surgery in setting of acetabular defects. Acetabular augments are a reliable option in case of Paprosky IIIB, IIIA defects and chronic pelvic discontinuity, providing good mechanical stability.

Short-term clinical efficacy of three dimension printed titanium augments for the reconstruction of acetabular bone defects in revision total hip arthroplasty

Objective To evaluate the short-term clinical efficacy of three dimension printed titanium augments for the reconstruction of acetabular bone defects in revision total hip arthroplasty. Methods The retrospective study was conducted. To retrospectively analyze clinical data of 21 patients who were underwent revision total hip arthroplasty with severe acetabular bone defects reconstructed by three dimension printed titanium augment from March 2016 to September 2017 from Department of Orthopaedics, Beijing Friendship Hospital, Capital Medical University. There were 9 males and 12 females, age (58.9±6.3) years, 51-67 years, body mass index (23.8±2.9) kg/m2. According preoperative CT scan of hip joints, three dimension printed titanium augments were designed for acetabular defects personality. The data including the vertical distance from centre of rotation to the interteardrop line in X-ray examination, preoperative Harris score, final follow-up Harris score of hip postoperatively, and complications were recorded. Outpatient visits ranged from 11.8 to 19.6 months. Measurement data were expressed as (Mean±SD), and t test was used before and after surgery. Results For X-ray examination, the average vertical distance from centre of rotation to the interteardrop line was (6.1±1.2) cm preoperatively and (2.8±0.7) cm postoperatively, and the difference was statistically significant(P<0.01). The hip Harris score increased from preoperative (47.5±6.4) scores to the last follow-up (84.6±5.9) scores, and the difference was statistically significant (P<0.01). The final follow-up data showed the acetabular prosthesis and augments were stable, while there were no hip joint dislocation, periprosthetic joint infection, loosening of acetabular components and other complications. Conclusion Three dimension printed augments can reconstruct severe acetabular bone defects and restore the hip rotation centre. Key words: Arthroplasty, replacement, hip; Prosthesis failure; Acetabulum; Osteolysis; Recovery of function

The influence of cavity preparation and press-fit cup implantation on restoring the hip rotation center

BackgroundReaming of the acetabular cavity and cup implantation directly influence the hip rotation center and contact area between implant and bone. Previous studies have reported on an altered rotation center after total hip arthroplasty, but have not studied the influence of reaming and cup implantation separately. Aim of this study was therefore to analyze the individual influence of acetabular reaming and subsequent cup implantation on the rotation center and how this influences the contact conditions at the bone-implant interface. MethodsAcetabular press-fit cups were implanted into the left and right hips of three full cadavers (n = 6). CT scans were performed to calculate the change in hip rotation center after reaming and prior to liner insertion. 3D models of the cups were used to determine the polar gap, the contact conditions and the effective press-fit. FindingsReaming the acetabular cavity shifted the rotation center medially (median 5.8 mm, range 4.8–9.1), superiorly (5.3 mm, 3.0–7.0) and posteriorly (2.9 mm, 1.0–5.3). With cup implantation, the rotation center shifted back towards the native position, but no full restoration was observed. The degree of shift increased with the size of polar gap (rs = 0.829, P = .042), which inversely reduced the contact area (rs = 0.886, P = .019). InterpretationThis study reveals that the dominant factor in hip rotation center restoration is the reaming process, while the cup implantation for a given nominal press-fit has only a small influence. Increasing the press-fit would improve the restoration but bares the danger of insufficient bone coverage and periprosthetic fractures due to the high forces needed.

High Hip Center Reduces the Dynamic Hip Range of Motion and Increases the Hip Load: A Gait Analysis Study in Hip Arthroplasty Patients With Unilateral Developmental Dysplasia

BackgroundLong-term favorable clinical outcomes of anatomical or high hip center techniques in total hip arthroplasty (THA) are reported in patients with developmental dysplasia of the hip (DDH). However, there is little information about the effect of the hip center location on gait characteristics. The purpose of this study was to compare these surgical techniques with gait analysis, analyze the effect of the hip rotation center location on gait parameters, and discuss the possible problems that may arise. MethodsA total of 40 patients who underwent THA due to unilateral coxarthrosis secondary to Crowe type III-IV DDH and completed 5 years of follow-up were included in the study. Group 1 included 20 patients who underwent anatomical hip center reconstruction, while group 2 included 20 patients who underwent high hip center reconstruction. Gait analysis was performed, and the groups were compared according to the gait characteristics. ResultsThe mean temporospatial values were similar between the groups. The extension of the operated side was significantly lower in group 2 (−9.11 ± 8.92) than in group 1 (−1.87 ± 11.51) (P = .04). The mean longitudinal hip joint force was found to be significantly higher in group 2 (8.92 N/kg ± 0.54) than in group 1 (8.16 N/kg ± 0.66) (P = .04). The high hip center technique has been shown to increase the load on the hip and restrict the dynamic range of motion. ConclusionThe high hip center technique can decrease the survival of the implant and increase the fall risk as it increases the load on the hip and reduces the dynamic range of motion. The hip center should be reconstructed anatomically when possible in DDH patients who undergo unilateral THA.

Changes in the spino-pelvic balance after hip replacement in patients with congenital hip dislocation

Objective. To analyze the features of the sagittal spino-pelvic balance formation in patients with congenital hip dislocation and its changes after total hip replacement with restoration of the rotation center. Material and Methods. A retrospective analysis of medical documentation of 47 patients with congenital hip dislocation was performed, a total of 62 total hip replacements were performed. Patients were divided into two groups: Group I with unilateral congenital hip dislocation (n = 26) and Group II – with bilateral hip dislocation (n = 21). The processing and study of statistical correlation were carried out using the Spearman method at p ≤ 0.05. Results. Patients with congenital hip dislocation had average preoperative value of the global lumbar lordosis of 64.1°, and the excess value of the sacral slope angle of 46.4°, which led to hyperlordosis. After surgery, the average value of the global lumbar lordosis was 57.2°, the sacral slope – 41.5°. There was a close relationship between these parameters (r = 0.787). Conclusions. Restoration of the hip rotation center in patients with congenital hip dislocation contributes to a decrease in the sacrum incidence, pelvic anteversion, and lordosis.

Anatomical study based on 3D-CT image reconstruction of the hip rotation center and femoral offset in a Chinese population: preoperative implications in total hip arthroplasty.

Several anatomical studies regarding the value of hip rotation center (HRC) and femoral offset (FO) have been performed in Western populations. However, there are a few data on hip morphological values in the Chinese population based on CT scans. This study measured the values of the hip and pelvis, especially HRC and FO, in a Chinese population and compared them with the published values obtained from Western populations. One hundred patients (50 females and 50 males) were included in the present study, and 3D-CT reconstructions of the hip and pelvis were generated. The mean age was 51.4 ± 8.9years and mean body mass index (BMI) was 23.5 ± 2.6kg/m2. All the morphologic measurements were compared between genders and sides, and the relationships between different parameters were analyzed. The mean FO values were 38.4 ± 4.7mm and 35.6 ± 4.4mm for the males and females, respectively. A significant negative correlation was noted between FO and neck shaft angle (NSA) in both genders (r = - 0.262, P = 0.009 for the males, r = - 0.350, P ≤ 0.001 for the females). A significant positive correlation was found between horizontal distance (HD) and diameter of the femoral head (DFH) in both genders (r = 0.734, P ≤ 0.001 for the males, r = 0.658, P ≤ 0.001 for the females). A significant positive correlation was noted between HD and pelvic width (PW) in males (r = 0.455, P ≤ 0.001). A significant positive correlation was also noted between HD and pelvic height (PH) in males (r = 0.318, P ≤ 0.001). A significant positive correlation was observed between FO and pelvic cavity height (PCH) in males (r = 0.411, P ≤ 0.001), and a significant positive correlation was observed between VD and PCH in females (r = 0.497, P ≤ 0.001). The tip of the greater trochanter was, on average, 7.0mm higher than the femoral head center. Relationships between DFH and pelvic morphometric parameters were also observed. The present morphological data and the relationships between them can be applied to design better ethnic-specific THA prostheses and preoperative plans.

Trabecular Titanium acetabular cups in hip revision surgery: mid-term clinical and radiological outcomes.

Severe acetabular bone loss during revision hip arthroplasty can be restored with different surgical techniques. Best results have been observed using porous tantalum cementless cups. Trabecular Titanium (TT) cups were designed to reproduce the structure, mechanical and biological characteristics of trabecular bone. Few clinical studies have been published with these cups. The aim of this study is to evaluate the clinical and radiological outcome of patients with large acetabular defects (Paprosky IIb or higher) revised using TT cups. 64 consecutive patients who underwent revision for total hip arthroplasty (THA) between 2011 and 2015 at our institution were enrolled. All were classified as Paprosky IIb, IIc, IIIa and IIIb. Periprosthetic joint infections and fractures were not included in this study. Radiographic and clinical (Harris Hip Score (HHS)) outcomes were evaluated. Kaplan-Meyer survivorship curve was performed. Complete data of 58 patients (mean follow-up 48.3 months) were analysed. 6 patients underwent a further revision (10.3%). Causes of re-revision were instability (5.2%), infection (3.4%) and aseptic loosening (1.7%). No radiolucent lines or signs of migration were observed. Survivorship was 94.8%. HHS Improved from a mean of 36.5-83.7. TT cups demonstrated encouraging results at mid-term follow-up. Cup modularity represented a helpful tool to restore hip rotation centre and to reduce the risk of dislocation. The capacity of trabecular titanium to induce bone growth and the versatility of modularity, make the Delta TT System a very useful aid for surgeons who are more frequently faced with complex revision.

Hip Range of Motion Estimation using CT-derived 3D Models

The success of the total hip arthroplasty is revealed as initial stability, range of motion, and long term pain, etc. Depending upon choice of implantation options such as femoral neck offset, diameter of the femoral head, the lateral opening tilt. Especially the impingement between femoral head component and acetabular cup limits the range of motion of the hip. In this sense, estimation or evaluation of the range of motion before and after the total hip arthroplasty is important. This study provides the details of a computer simulation technique for the hip range of motion of intact hip as well as arthroplasty. The suggested method defines the hip rotation center and rotation axes for flexion and abduction, respectively. The simulation uses CT-based reconstructed 3D models and an STL treating software. The abduction angle of the hip is defined as the superolateral rotation angle from sagittal plane. The flexion angle of the hip is defined as the superoanterior angle from the coronal plane. The maximum abduction angle is found as the maximum rotation angle by which the femoral head can rotate superolaterally about the anterior-posterior axis without impingement. The maximum flexion angle is found as the maximum rotation angle by which the femoral head can rotate superoanteriorly about the medial-lateral axis without impingement. Compared to the normal hip, the total hip replacement hip showed decreased abduction by 60 degrees and decreased flexion by 4 degrees. This measured value implies that the proposed measurement technique can make surgeons find a modification of increase in the femoral neck offset or femoral head, to secure larger range of motion.

Total hip arthroplasty in treating acetabular protrusion secondary to rheumatoid arthritis

Objective To investigate the clinical outcomes of total hip arthroplasty in treatment of severe acetabular protrusion secondary to rheumatoid arthritis. Methods From January 2011 to November 2014, eighteen patients (20 hips) with severe acetabular protrusion secondary to rheumatoid arthritis were treated with total hip arthroplasty (THA), including 6 males (6 hips) and 12 females (14 hips). The age ranged from 37 to 68 years (average, 45.8±8.3 year). According to the classification of Sotelo-Garza and Charnley, there were 15 cases (17 hips) of type II (acetabular protrusion 6-15 mm) and 3 cases (3 hips) of type III (acetabular protrusion >15 mm). During the surgery, the femoral heads were moved out through retrograde method after the osteotomy of femoral neck by posterolateral approach. All patients underwent THA with autogenous bone graft by impacting technique for reconstruction of acetabula, and the cementless cups were planted with press-fit skills (Tantalum trabecular metal cup in 16 cases and Titanium porous coating cup in 4 cases). The hip function was evaluated by using Harris hip score. Radiographic measurement was performed with X-ray films to assess the restoration of the hip rotation center, graft incorporation and sign of prostheses loosening in follow-up duration. Results The mean operation duration and intraoperative blood loss were 89.5±8.1 min (range 55-131 min) and 295±10.9 ml (range 165-480 ml) respectively. The average amount of bone graft was 33.7±6.8 cm3 (range 32.5-61.2 cm3) in reconstruction of protrusion acetabulum. The mean follow up duration was 4.5±1.7 years (range 2.5-6.0 years). The horizontal distance between the center of femoral head and the Kohler's line was increased from preoperative 8.87±3.9 mm (range -11.11 -12.78 mm) to 23.55±2.5 mm (range 21.23-25.57 mm) postoperatively, and the vertical distance between the center of femoral head and the line joining the bilateral ischial tuberosities was decreased from preoperative 87.45±3.5 mm (range 74.75-96.97mm) to postoperative 77.83±4.1 mm (range 68.22-90.40 mm) with statistically significant difference. The bone incorporation was achieved at 6 months postoperatively in radiological film. No loosening of acetabular components was found in final fellow-up. At last follow-up, Harris hip score was significantly improved from 55.3±9.5 points preoperatively to 92.2±12.7 postoperatively (t=51.569, P=0.000). The range of flexion of the hip significantly improved from 41.5°±6.7° preoperatively to 102.3°±14.5° at finial follow-up (t=64.865, P=0.000), and the range of extension of the hip improved from 8.2°±3.5° preoperatively to 29.8°±6.6° at finial follow-up (t=51.161, P=0.000). The discrepancy was significantly decreased from 23.7±0.82 mm preoperatively to 4.7±0.39 mm postoperatively (t=19.761, P=0.000). Mild thigh pain was reported in two hips, which typically occurred only with prolonged activity without disabling and not requiring medication. Conclusion Total hip arthroplasty with impaction bone grafting and cementless modular cup can recover the acetabular center of rotation and achieve satisfactory short-term outcomes in treating patients severe protrusion acetabula secondary to rheumatoid arthritis. Key words: Arthroplasty, replacement, hip; Arthritis, rheumatoid; Acetabulum; Bone transplantation; Transplantation, autologous