Hip range of motion during daily activities in patients with posterior pelvic tilt from supine to standing position

In most patients with hip disorders, the anterior pelvic plane (APP) sagittal tilt does not change from supine to standing position. However, in some patients, APP sagittal tilt changes more than 10° posteriorly from supine to standing position. The purpose of this study was to both examine APP sagittal tilt and investigate the hip flexion and extension range of motion (ROM) required during daily activities in these atypical patients. Patient‐specific 4‐dimensional (4D) motion analysis was performed for 50 hips from 44 patients who had undergone total hip arthroplasty. All patients divided into two categories, such as atypical patients for whom the pelvis tilted more than 10° posteriorly from supine to standing position preoperatively (19 hips from 18 patients) and the remaining typical patients (31 hips from 26 patients). The required hip flexion and extension angles did not differ significantly between atypical patients and typical patients. In conclusion, the hip flexion ROM during deep bending activities and hip extension ROM during extension activities required in those atypical patients with pelvic tilt more than 10° backward from supine to standing position did not shift in the direction of extension. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:542–547, 2015.     

Movement Mapping as dynamic preoperative surgical planning in total hip replacement

The purpose of the present study was to develop and present a computer program for preoperative simulation of implant components placement in total hip alloarthroplasty, and its influence on the possible range of motion (ROM). We evaluated a computer simulation for preoperative estimation of range of motion (movement mapping) in total hip replacement. The computer program was based on Borland C++. The system had an open data port, so the data could be transferred to an Excel spreadsheet for statistical evaluation. With the developed virtual computer simulation, a practical model was established. The model showed range of motion patterns which correspond to clinical experience. ROM was best at a shaft anteversion between 20 degrees and 30 degrees. ROM had its maximum with a CCD angle of 120 degrees -130 degrees. Acetabular cup anteversion was optimal between 10 degrees and 20 degrees, and cup inclinations were optimal below 40 degrees. The presented movement mapping system seems to be a reliable option for dynamic preoperative planning, which may be a prerequisite for the use of intraoperative navigation systems.     

The frontal pelvic plane provides a valid reference system for implantation of the acetabular cup: Spatial orientation of the pelvis in different positions

Background?The frontal pelvic plane has traditionally served as the reference plane for implantation of the acetabular cup during total hip arthroplasty, with referencing performed with the patient supine on the operating table. During daily activities in an upright position, the frontal pelvic plane changes from a horizontal to a vertical orientation. If this change in orientation is accompanied by a substantial change in pelvic inclination angle, it would mean that the use of the frontal pelvic plane as a reference plane for implantation of the acetabular cup would not be valid for proper alignment of the cup. To evaluate this possibility, we measured the change of inclination of the pelvis from the supine to the standing position.

Subjects and methods We evaluated 120 patients, first positioned in a standing position and then supine on a table. Three pelvic landmarks were digitized percutaneously, and the spatial coordinates were calculated with regard to pelvic orientation in the horizontal and the vertical plane.

Results?We found a mean inclination of 6.7° in the standing position and 5.6° in the supine position. Patients who were more than 60 years of age who did not have coxarthrosis had a greater inclination angle (8.7°) while standing. Pelvic orientation was stable with regard to the supine and standing positions. These results were independent of sex, level of arthrosis, or status after implantation of a total hip replacement.

Interpretation?The frontal pelvic plane is a valid reference plane for implantation of the acetabular cup.

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The frontal pelvic plane provides a valid reference system for implantation of the acetabular cup: spatial orientation of the pelvis in different positions

Background The frontal pelvic plane has traditionally served as the reference plane for implantation of the acetabular cup during total hip arthroplasty, with referencing performed with the patient supine on the operating table. During daily activities in an upright position, the frontal pelvic plane changes from a horizontal to a vertical orientation. If this change in orientation is accompanied by a substantial change in pelvic inclination angle, it would mean that the use of the frontal pelvic plane as a reference plane for implantation of the acetabular cup would not be valid for proper alignment of the cup. To evaluate this possibility, we measured the change of inclination of the pelvis from the supine to the standing position.

Subjects and methods We evaluated 120 patients, first positioned in a standing position and then supine on a table. Three pelvic landmarks were digitized percutaneously, and the spatial coordinates were calculated with regard to pelvic orientation in the horizontal and the vertical plane.

Results We found a mean inclination of 6.7° in the standing position and 5.6° in the supine position. Patients who were more than 60 years of age who did not have coxarthrosis had a greater inclination angle (8.7°) while standing. Pelvic orientation was stable with regard to the supine and standing positions. These results were independent of sex, level of arthrosis, or status after implantation of a total hip replacement.

Interpretation The frontal pelvic plane is a valid reference plane for implantation of the acetabular cup.

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Sagittal pelvic mal-rotation and positioning of the acetabular component in total hip arthroplasty: Three-dimensional computer model analysis.

Mal-rotation of pelvis on the sagittal plane, which is common in patients with fixed spinal kyhposis, for example, ankylosing spondylitis, can cause error in cup positioning when hip arthroplasty is performed. The present study was performed to quantify the effects of sagittal pelvic mal-rotation on the final cup position and to evaluate different methods of cup positioning to compensate for the mal-rotation. Three-dimensional reconstruction of computer tomograms of 15 sets of full pelvi was performed. Two methods of cup insertion were simulated and compared: a method mimicking genuine surgery (anatomical positioning) and one that compensates for the sagittal pelvic mal-rotation (functional positioning). Sagittal pelvic mal-rotation of more than 20 degrees , if ignored, resulted in a cup with an anterversion of more than 30 degrees and an inclination of more than 55 degrees. Half of the cup surface was not in contact with host bone when the cup position was maintained at 20 degrees anteversion and 45 degrees inclination in a patient with 50 degrees sagittal pelvic mal-rotation. The usual method of cup positioning may need to be modified in patients with sagittal pelvic mal-rotation in order to maintain the desired cup position. For each 10 degrees of sagittal pelvic mal-rotation beyond 20 degrees of mal-rotation, the cup needs to be put in such that it is 5 degrees less inclined and anteverted.     

Image-based hip navigation

After experimental and preclinical evaluation (HAP Paul Award 2001) of a CT-free image-guided surgical navigation system for acetabular cup placement, the system was introduced into clinical routine. The computation of the angular orientation of the cup is based on reference coordinates from the anterior pelvic plane (APP) concept. A hybrid strategy for pelvic landmark acquisition has been introduced involving percutaneous pointer-based digitization with the noninvasive biplanar landmark reconstruction using multiple registered fluoroscopy images. From January 2001 to May 2002, 118 consecutive patients (mean age 68 years, 82 male, 36 female, and 62 left and 56 right hip joints) were operated on with the hybrid CT-free navigation system. During each operation, the angular orientation of the inserted implant was recorded. To determine the placement accuracy of the acetabular components, the first 50 consecutive patients underwent a CT scan 7-10 days postoperatively to analyze the cup position relative to the APP. This was done blinded with commercial planning software. There was no significant learning curve observed for the use of the system. Mean values for postoperative inclination read 43 degrees (SD 3.0, range 37-49) and anteversion 19 degrees (SD 3.9, range 10-28). The resulting system accuracy, i.e., the difference between intraoperatively calculated cup orientation and postoperatively measured implant position, shows a maximum error of 5 degrees for the inclination (mean 1.5 degrees, SD 1.1) and 6 degrees for the anteversion (mean 2.4 degrees, SD 1.3). An accuracy of better than 5 degrees inclination and 6 degrees anteversion was achieved under clinical conditions, which implies that there is no significant difference in performance from the established CT-based navigation methods. Image-guided CT-free cup navigation provides a reliable solution for future total hip arthroplasty (THA).     

Measurements of pelvic flexion angle using three-dimensional computed tomography

The purpose of the current study was to evaluate whether safe acetabular component position depends on differences in pelvic location between the supine, standing, and sitting positions. The subjects of the current study were 101 patients who had total hip arthroplasty. Anteroposterior radiographs of the pelvis with the patients in the supine, standing, and sitting positions were obtained preoperatively and 1 year after total hip arthroplasty. Computed tomography images of the pelvis were obtained preoperatively. Using image matching between the three-dimensional computed tomography model and anteroposterior radiograph, pelvic flexion angles with the patient in the supine, standing, and sitting positions were calculated. The mean preoperative pelvic flexion angle was 5 degrees +/- 9 degrees (range, -37 degrees -30 degrees ) in the supine position, 3 degrees +/- 12 degrees (range, -46 degrees -33 degrees ) in the standing position, and -29 degrees +/- 12 degrees (range, -62 degrees -10 degrees ) in the sitting position. Because there was much intersubject variability in pelvic flexion angle, it is not appropriate to determine orientation of the acetabular component from anatomic landmarks. In 90% of the cases, the difference in pelvic flexion angle between the supine and standing positions preoperatively was 10 degrees or less. In 90% of the cases, there was 20 degrees or greater extension of the pelvis from the supine position to the sitting position preoperatively, and the safe range of flexion of the hip from anterior prosthetic impingement in the sitting position was 20 degrees or greater than that in the supine position. Preoperative pelvic position in each case was almost completely maintained 1 year after total hip arthroplasty. It is reasonable to regard the pelvic position in the supine position as the functional pelvic position and proper pelvic reference frame in determining optimal orientation of the acetabular component in 90% of cases before and 1 year after total hip arthroplasty, although an adjustment of orientation of the acetabular component was needed for the remaining cases.     

Change in pelvic tilt angle 2 to 4 years after total hip arthroplasty

The purpose of this study was to evaluate the change in pelvic tilt angle (PA) in the sagittal plane in the standing and supine positions for 2 to 4 years after total hip arthroplasty (THA). Anteroposterior pelvic radiographs of 21 male and 65 female patients were investigated before and after THA yearly over 2 to 4 years. Both the standing and supine PA significantly posteriorly tilted after THA. The difference in PA between the standing and supine positions (dPA) significantly increased after THA. Although the PA in the standing and supine positions plateaued 1 year after THA, the dPA gradually increased. In addition, the percentage of patients who showed a difference of more than 10° in dPA tended to increase yearly. In particular, elderly female patients who showed posterior tilt in PA in the standing or supine positions or a large dPA before THA tended to show a dPA of more than 10° after THA.     

How does anteroposterior cup placement affect bone coverage and range of motion in primary total hip arthroplasty for hip dysplasia?

Background

Due to anterior bone defects, high and/or posterior placement of an acetabular cup is often required to achieve sufficient coverage in patients with hip dysplasia. We examined whether posterior cup placement affected the postoperative range of motion (ROM) in primary total hip arthroplasty (THA).

C-arm based navigation in total hip arthroplasty-background and clinical experience

After experimental and preclinical evaluation of a CT-free image guided surgical navigation system for acetabular cup placement, the system was introduced into clinical routine. The computation of the angular orientation of the cup is based on reference coordinates from the anterior pelvic plane concept. A hybrid strategy for pelvic landmark acquisition has been introduced, involving percutaneous pointer-based digitization with the noninvasive bi-planar landmark reconstruction using multiple registered fluoroscopy images. From January 2001 to October 2003, a total of 236 consecutive patients (mean age 66 years, 144 male, 92 female, 124 left and 112 right hip joints) were operated on with the hybrid CT-free navigation system. During each operation, the angular orientation of the inserted implant was recorded. To determine the placement accuracy of the acetabular components, the first 50 consecutive patients underwent a CT scan 7-10 days postoperatively to analyze the cup position relative to the anterior pelvic plane. This procedure was done blinded and with commercial planning software. There was no significant learning curve observed for the use of the system. Mean values for postoperative inclination read 42 degrees (SD 3.6, range (37-49)) and anteversion 21 degrees (SD 3.9, range (10-28)). The resulting system accuracy, ie, the difference between intraoperatively calculated cup orientation and postoperatively measured implant position shows a maximum error of 5 degrees for the inclination (mean 1.5 degrees, SD 1.1) and 6 degrees for the anteversion (mean 2.4 degrees, SD 1.3). An accuracy of better than 5 degrees inclination and 6 degrees anteversion was achieved under clinical conditions, which implies that there is no significant difference in performance from the established CT-based navigation methods. Image-guided CT-free cup navigation provides a reliable solution for future total hip arthroplasty (THA).     

The acetabulum: The elusive home run of THR

The objective is to describe the current factors for optimizing positioning of the acetabular component in THR. The emphasis in cup placement today is personalizing the component position for each patientʼs anatomy rather than a “one size fits all” (always put the cup in the same position such as 45° inclination and 15° anteversion). To individualize, the arthroplasty requires remembering the operation is on both sides of the joint (combined anteversion) and implanting the cup in the functional plane of that patient, which requires knowledge of the pelvic tilt at surgery and the changes in the spine−pelvic−hip construct between standing and sitting for that patient. To individualize, the cup position will demand higher precision than has been accepted in the past, such as computer navigation, to augment the experience and instinct of the surgeon in performing total hip replacement. In conclusion, acetabular cup placement is an elusive home run because the complexity of its positioning for each patient requires new preoperative planning, and more precise intraoperative positioning.     

Can pelvic tilting be ignored in total hip arthroplasty?

INTRODUCTION

The orientation of acetabular component is influenced by pelvic tilt, body position and individual variation in pelvic parameters. Most post-operative adverse events may be attributed to malposition of the component in the functional position. There is evidence that orientation of the pelvis changes from the supine to standing position. Authors report a case of recurrent dislocation after total hip arthroplasty due to excessive pelvic tilting.PRESENTATION OF CASE A 69-year old female with coxarthrosis had undergone total hip replacement with recurrent dislocation of the hip on bearing weight in spite of using constrained acetabular component.

DISCUSSION

Our case report substantiates the influence of pelvic tilt, incurred by a sagittal deformity of spine, on dynamic orientation of the acetabular cup which was positioned in accordance with the anatomic landmarks alone. If the reference is only bony architecture and dynamic positions of the pelvis are not taken into account, improper functional orientation of the acetabular cup can result in sitting and standing positions. These can induce instability even in anatomically appropriately oriented acetabular component.

CONCLUSION

The sagittal position of pelvis is a key factor in impingement and dislocation after total hip arthroplasty. Pelvic tilting affects the position of acetabular component in the sagittal plane of the body as compared with its anatomic position in the pelvis. We suggest a preoperative lateral view of spine-pelvis, in upright and supine position for evaluation of a corrective adaptation of the acetabular cup accordingly with pelvic balance.     

Navigated total hip arthroplasty using a 3-D freehand ultrasound system: technical note and preliminary results

Ultrasound-navigated cementless total hip arthroplasty (THA) was performed in 10 consecutive patients with primary osteoarthritis of the hip between August 2008 and October 2009 (M:F, 6:4; median age, 61 years; age range, 30-86 years). The pelvic orientation was defined by preoperative digitization and registration of bony landmarks. Cup inclination and anteversion were documented for each patient intraoperatively (epidigitized vs ultrasound-assessed landmarks). The median difference between the palpated and ultrasound anterior pelvic plane was 8° (range, 4°-18°) for pelvic tilt (rotation around the transversal axis), 1° (range, -3° to 2°) for rotation around the longitudinal axis, and 0.25° (range, -2.0° to 5.0°) for rotation around the sagittal axis. The median difference in cup orientation resulting from pelvic tilt error was 6° (range, 3°-13°) for anteversion and 3° (range, -1° to 5°) for inclination. There were no intra- or postoperative complications. The measured width of soft tissue layer anterior to the pelvic symphysis correlated significantly with the measured difference in cup inclination and anteversion. One centimeter of soft tissue anterior to the symphysis resulted in a median 2° (range, 1.75°-2.3°) difference in pelvic tilt. Ultrasound-assisted navigation in THA is a promising technology able to eliminate systematic errors in anterior pelvic plane orientation, in contrast to conventionally navigated THA using percutaneous palpation of landmarks or THA without navigational support.     

Compliant positioning of total hip components for optimal range of motion.

Impingement between femoral neck and endoprosthetic cup is one of the causes for dislocation in total hip arthroplasty (THA). Choosing a correct combined orientation of both components, the acetabular cup and femoral stem, in manual or computer-assisted implantation will yield a maximized, stable range of motion (ROM) and will reduce the risk for dislocation. A mathematical model of a THA was developed to determine the optimal combination of cup inclination, cup anteversion, and stem antetorsion for maximizing ROM and minimizing the risk for cup-neck impingement. Single and combined hip joint motions were tested. A radiographic definition was used for component orientation. Additional parameters, such as stem-neck (CCD) angle, head-neck ratio, and the design of the acetabular opening, were also considered. The model showed that a maximized and safe ROM requires compliant, well-defined combinations of cup inclination, cup anteversion, and stem antetorsion depending on the intended ROM. Radiographic cup anteversion and stem antetorsion were linearly correlated. Additional internal rotation reduced flexion, and additional external rotation reduced extension, abduction and adduction. The articulating hemispheric surface of acetabular cups should be oriented between 40 degrees and 45 degrees of radiographic inclination, between 20 degrees and 28 degrees of radiographic cup anteversion, and should be combined with stem antetorsion so that the sum of cup anteversion plus 0.7 times the stem antetorsion equals 37 degrees. Final component orientation must also consider cup containment, implant impingement with bone and soft tissue, and preoperative skeletal contractures or deformities to achieve the optimal compromise for each patient.     

The transverse pelvic plane: a new and practical reference frame for hip arthroplasty.

Acetabular orientation is a crucial part of the planning and performance of hip arthroplasty. Currently, most surgeons use the anterior pelvic plane (APP) to orient themselves when navigating the acetabulum, despite the fact that the anterior superior iliac spine (ASIS) of the unaffected side is not accessible in the lateral position. We have identified another plane, the transverse pelvic plane (TPP), relying on both posterior superior iliac spines and the ASIS of the affected side. In a CT-based study, this plane was found to be as reliable as the APP for the orientation of the cup in both anteversion and inclination. The substantial variation in both measurements between patients is documented, and their relation to the "safe zone" is shown. We recommend consideration of the TPP by surgeons who perform arthroplasty in the lateral position. It may reduce operating time and improve accuracy in computer-assisted arthroplasty.     

Chiari pelvic osteotomy for advanced osteoarthritis in patients with hip dysplasia

BACKGROUND: It is not clear whether a Chiari pelvic osteotomy performed for the treatment of advanced osteoarthritis can delay the need for total hip arthroplasty. We present the mid-term results of the Chiari pelvic osteotomy performed for the treatment of T?nnis grade-3 osteoarthritis (large cysts, severe narrowing of the joint space, or severe deformity or necrosis of the head with extensive osteophyte formation), with a particular focus on whether this procedure can delay the need for total hip arthroplasty. METHODS: We followed thirty-two hips in thirty-one patients with T?nnis grade-3 osteoarthritis who had refused total hip arthroplasty and had been treated with a Chiari pelvic osteotomy. The mean age at the time of surgery was 35.2 years. The mean duration of follow-up was 11.2 years, at which time clinical evaluation with the Harris hip score and radiographic evaluation were performed. RESULTS: The average Harris hip score improved from 52 points preoperatively to 77 points at the time of follow-up; the average pain score improved from 20 to 31 points. Three hips with a hip score of <70 points required total hip arthroplasty. With a hip score of <70 points as the end point, the cumulative rate of survival at ten years was 72%. The clinical outcome was significantly influenced by the preoperative center-edge angle (p = 0.004), the preoperative acetabular head index (p = 0.039), achievement of the appropriate osteotomy level (p = 0.011), and superior migration (p = 0.009) and lateral migration (p = 0.026) of the femoral head. CONCLUSIONS: Although the clinical results were inferior to those of total hip arthroplasty, Chiari pelvic osteotomy may be an option for young patients with advanced osteoarthritis who prefer a joint-conserving procedure to total hip arthroplasty and accept a clinical outcome that is predicted to be less optimal than that of total hip arthroplasty. Moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative center-edge angle of at least -10 degrees are desirable selection criteria.     

Intraoperative pelvic movement is associated with the body mass index in patients undergoing total hip arthroplasty in the supine position

BackgroundsThere are very few reports on pelvic movement during total hip arthroplasty (THA) in the supine position. We investigated intraoperative pelvic motion in the sagittal and axial planes to determine if preoperative clinical factors, including body mass index (BMI) affect intraoperative pelvic motion.MethodsFifty-three patients with osteoarthritis undergoing THA in the supine position were included. Clinical factors, such as age, BMI, and pelvic tilt were assessed preoperatively. Intraoperative pelvic motion in the axial and sagittal planes was assessed using a portable navigation system. We assessed the change in pelvic tilt from registration to cup implantation as the pelvic tilt change; positive values indicated anterior pelvic tilt. We measured the values and absolute values of changes in axial rotation from registration to cup implantation to determine the axial rotation angle. The effects of patient factors on pelvic motion (pelvic tilt change and axial rotation angle) were analyzed using a Spearman's correlation analysis.ResultsPreoperative pelvic tilt was negatively correlated with pelvic tilt change (r = −0.57, p < 0.05) and the absolute axial rotation angle (r = −0.57, p < 0.05). BMI and absolute axial rotation angle were negatively correlated (r = −0.54, p < 0.05). Age was not correlated with change in the pelvic tilt and the axial rotation angle.ConclusionsPreoperative pelvic tilt and BMI are important factors to determine intraoperative pelvic motion in patients who undergo THA in the supine position. This can help surgeons to preoperatively identify patients with a higher risk of intraoperative pelvic motion.     

Total hip arthroplasty in acetabular fractures

Total Hip Arthroplasty (THA) is a well-accepted treatment for established hip arthritis following acetabular fractures. If a conservatively managed or operated case progresses to non-union/mal-union failing to restore the joint integrity, it may eventually develop secondary arthritis warranting a total hip arthroplasty. Also, in recent years, acute total hip arthroplasty is gaining importance in conditions where the fracture presents with pre-existing hip arthritis, is not amenable to salvage by open reduction and internal fixation, or, a poor prognosis is anticipated following fixation.There are several surgical challenges in performing total hip arthroplasty for acetabular fractures whether acute or delayed. As a separate entity elderly patients pose a distinct challenge due to osteoporosis and need stable fixation for early weight bearing alleviating the risk of any thromboembolic event, pulmonary complications and decubitus ulcer. The aim of surgery is to restore the columns for acetabular component implantation rather than anatomic fixation. Meticulous preoperative planning with radiographs and Computed Tomography (CT) scans, adequate exposure to delineate the fracture pattern, and, availability of an array of all instruments and possible implants as backup are the key points for success. Previous implants if any should be removed only if they are in the way of cup implantation or infected. Press fit uncemented modern porous metal acetabular component with multiple screw options is the preferred implant for majority of cases. However, complex fractures may require major reconstruction with revision THA implants especially when a pelvic discontinuity is present.     

Total hip arthroplasty in acetabular fractures

Total Hip Arthroplasty (THA) is a well-accepted treatment for established hip arthritis following acetabular fractures. If a conservatively managed or operated case progresses to non-union/mal-union failing to restore the joint integrity, it may eventually develop secondary arthritis warranting a total hip arthroplasty. Also, in recent years, acute total hip arthroplasty is gaining importance in conditions where the fracture presents with pre-existing hip arthritis, is not amenable to salvage by open reduction and internal fixation, or, a poor prognosis is anticipated following fixation.There are several surgical challenges in performing total hip arthroplasty for acetabular fractures whether acute or delayed. As a separate entity elderly patients pose a distinct challenge due to osteoporosis and need stable fixation for early weight bearing alleviating the risk of any thromboembolic event, pulmonary complications and decubitus ulcer. The aim of surgery is to restore the columns for acetabular component implantation rather than anatomic fixation. Meticulous preoperative planning with radiographs and Computed Tomography (CT) scans, adequate exposure to delineate the fracture pattern, and, availability of an array of all instruments and possible implants as backup are the key points for success. Previous implants if any should be removed only if they are in the way of cup implantation or infected. Press fit uncemented modern porous metal acetabular component with multiple screw options is the preferred implant for majority of cases. However, complex fractures may require major reconstruction with revision THA implants especially when a pelvic discontinuity is present.