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Background and Objectives: Total hip arthroplasty (THA) requires accurate implant placement to ensure optimal outcomes. In this study, the AR Hip navigation system, an imageless portable navigation tool using augmented reality (AR), was evaluated for measuring radiographic inclination (RI), anteversion (RA), leg lengthening (LL), and offset (OS) changes in supine and lateral decubitus THA. Notably, this is the first report to assess the accuracy of LL and OS measurements using AR technology. Methods: We analyzed 48 hips from primary THA patients: 17 in the supine (S) group and 31 in the lateral (L) group. RI, RA, LL, and OS were measured intraoperatively using AR Hip and postoperatively using Zed Hip 3D software (Version 18.0.0.0). The absolute errors and outlier rates (≥5° for RI/RA and ≥5 mm for LL/OS) were compared between groups. Results: The mean intraoperative RI values with AR Hip were 40.1 ± 0.6° (S), 40.2 ± 1.2° (L), and 40.1 ± 1.0° (total), while the postoperative RI values with Zed Hip were 39.7 ± 2.9° (S), 39.5 ± 2.5° (L), and 39.6 ± 2.6° (total). The absolute errors were 1.8 ± 1.7° (total), with no significant group differences (p = 0.957). For RA, the errors were 2.0 ± 1.2° (total) (p = 0.771). The LL errors were 2.3 ± 2.2 mm (total) (p = 0.271), and the OS errors were 3.5 ± 2.8 mm (total) (p = 0.620). The outlier rates for RI were 11.8% (S) and 3.2% (L); for RA, 0% (S) and 3.2% (L); for LL, 29.4% (S) and 6.5% (L) with a significant difference (p = 0.031); and for OS, 23.5% (S) and 25.8% (L). No significant differences were observed for RI, RA, or OS. Conclusions: AR Hip provided accurate measurements of cup orientation, LL, and OS in both supine and lateral THA. Importantly, this study is the first to report the accuracy of LL and OS measurements using AR technology, demonstrating the potential of AR Hip for improving THA precision. [ABSTRACT FROM AUTHOR]

Preoperative planning in total hip arthroplasty (THA) involves utilizing radiographs or advanced imaging modalities, including computerized tomography scans, for precise prediction of implant sizing and positioning. This study aimed to compare 3-dimensional (3D) versus 2-dimensional (2D) preoperative planning in primary THA with respect to key surgical metrics, including restoration of the horizontal and vertical center of rotation (COR), combined offset, and leg length. This study included 60 patients undergoing primary THA for symptomatic hip osteoarthritis (OA), randomly allocated to either robotic arm–assisted or conventional THA. Digital 2D templating and 3D planning using the robotic software were performed for all patients. All measurements to evaluate the accuracy of templating methods were conducted on the preoperative computerized tomography scanogram, using the contralateral hip as a reference. Sensitivity analyses explored differences between 2D and 3D planning in patients who had superolateral or medial OA patterns. Compared to 2D templating, 3D templating was associated with less medialization of the horizontal COR (−1.2 versus −0.2 mm, P =.002) and more accurate restoration of the vertical COR (1.63 versus 0.3 mm, P <.001) with respect to the contralateral side. Furthermore, 3D templating was superior for planned restoration of leg length (+0.23 versus −0.74 mm, P =.019). Sensitivity analyses demonstrated that in patients who had medial OA, 3D planning resulted in less medialization of horizontal COR and less offset reduction. Conversely, in patients who had superolateral OA, there was less lateralization of horizontal COR and less offset increase using 3D planning. Additionally, 3D planning showed superior reproducibility for stem, acetabular cup sizes, and neck angle, while 2D planning often led to smaller stem and cup sizes. Our findings indicated higher accuracy in the planned restoration of native joint mechanics using 3D planning. Additionally, this study highlights distinct variances between the 2 planning methods across different OA pattern subtypes, offering valuable insights for clinicians employing 2D planning. [ABSTRACT FROM AUTHOR]

Aims: Precise implant positioning, tailored to individual spinopelvic biomechanics and phenotype, is paramount for stability in total hip arthroplasty (THA). Despite a few studies on instability prediction, there is a notable gap in research utilizing artificial intelligence (AI). The objective of our pilot study was to evaluate the feasibility of developing an AI algorithm tailored to individual spinopelvic mechanics and patient phenotype for predicting impingement. Methods: This international, multicentre prospective cohort study across two centres encompassed 157 adults undergoing primary robotic arm-assisted THA. Impingement during specific flexion and extension stances was identified using the virtual range of motion (ROM) tool of the robotic software. The primary AI model, the Light Gradient-Boosting Machine (LGBM), used tabular data to predict impingement presence, direction (flexion or extension), and type. A secondary model integrating tabular data with plain anteroposterior pelvis radiographs was evaluated to assess for any potential enhancement in prediction accuracy. Results: We identified nine predictors from an analysis of baseline spinopelvic characteristics and surgical planning parameters. Using fivefold cross-validation, the LGBM achieved 70.2% impingement prediction accuracy. With impingement data, the LGBM estimated direction with 85% accuracy, while the support vector machine (SVM) determined impingement type with 72.9% accuracy. After integrating imaging data with a multilayer perceptron (tabular) and a convolutional neural network (radiograph), the LGBM’s prediction was 68.1%. Both combined and LGBM-only had similar impingement direction prediction rates (around 84.5%). Conclusion: This study is a pioneering effort in leveraging AI for impingement prediction in THA, utilizing a comprehensive, real-world clinical dataset. Our machine-learning algorithm demonstrated promising accuracy in predicting impingement, its type, and direction. While the addition of imaging data to our deep-learning algorithm did not boost accuracy, the potential for refined annotations, such as landmark markings, offers avenues for future enhancement. Prior to clinical integration, external validation and larger-scale testing of this algorithm are essential. Cite this article: Bone Jt Open 2024;5(8):671–680.

Abstract Background Implant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement. However, optimal implant placement remains a challenge. Moreover, the effect of changes in offset on dislocation is still unclear. In this study, we aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation. Methods Included were patients who underwent primary cementless THA between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were rated as poor CA. The dislocation rates were compared between the good and poor CA groups and between the groups with and without increased offset. Results A total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (P

Abstract Background Modular neck femoral stems are advantageous because they can accurately restore the ideal hip geometry using various options in terms of offset, length, and version. However, there are concerns regarding junctional problems. Despite several reports on such issues, there is a lack of study on mid- to long-term results of these stems. The current study evaluated the mid-term results of patients who underwent primary total hip arthroplasty using a titanium–titanium (Ti–Ti) modular neck femoral stem. Methods In total, data on 47 hips (42 patients) that could be followed-up for ≥ 5 years after primary total hip arthroplasty using the Ti–Ti modular neck femoral stem from 2011 to 2015 were reviewed. There were 22 male and 20 female patients, and their mean age was 56.3 (range: 31–76) years. The mean follow-up period was 8 (range: 5–12) years. Functional and radiological outcomes, complications, and reoperations were investigated. In addition, we conducted a comparative analysis of the outcomes between those who underwent surgery using the Ti–Ti modular neck femoral stem and 41 hips (35 patients, 19 males and 16 females) that underwent primary total hip arthroplasty using nonmodular femoral stems as a control. Results In all Ti–Ti cases, the mean Harris Hip Scores were 50.6 (range: 6–59) preoperatively and 92.7 (range: 78–99) at the last follow-up (P

Background: Implant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement. However, optimal implant placement remains a challenge. Moreover, the effect of changes in offset on dislocation is still unclear. In this study, we aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation. Methods: Included were patients who underwent primary cementless THA between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were rated as poor CA. The dislocation rates were compared between the good and poor CA groups and between the groups with and without increased offset. Results: A total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (P < 0.05). The dislocation rate was significantly lower in the good CA group (P < 0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (P = 0.004). There were no dislocations in patients with good CA and increased offset. Conclusions: The dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side. [ABSTRACT FROM AUTHOR]

Background: Modular neck femoral stems are advantageous because they can accurately restore the ideal hip geometry using various options in terms of offset, length, and version. However, there are concerns regarding junctional problems. Despite several reports on such issues, there is a lack of study on mid- to long-term results of these stems. The current study evaluated the mid-term results of patients who underwent primary total hip arthroplasty using a titanium–titanium (Ti–Ti) modular neck femoral stem. Methods: In total, data on 47 hips (42 patients) that could be followed-up for ≥ 5 years after primary total hip arthroplasty using the Ti–Ti modular neck femoral stem from 2011 to 2015 were reviewed. There were 22 male and 20 female patients, and their mean age was 56.3 (range: 31–76) years. The mean follow-up period was 8 (range: 5–12) years. Functional and radiological outcomes, complications, and reoperations were investigated. In addition, we conducted a comparative analysis of the outcomes between those who underwent surgery using the Ti–Ti modular neck femoral stem and 41 hips (35 patients, 19 males and 16 females) that underwent primary total hip arthroplasty using nonmodular femoral stems as a control. Results: In all Ti–Ti cases, the mean Harris Hip Scores were 50.6 (range: 6–59) preoperatively and 92.7 (range: 78–99) at the last follow-up (P < 0.001). Regarding the neck component's modularity, straight neck components were used in all Ti–Ti cases, and an anteverted or a retroverted neck was not used in any case. Stem revision was performed in one hip due to aseptic loosening. One hip underwent open reduction and internal fixation due to periprosthetic fracture without stem loosening. There were no cases of osteolysis and periprosthetic joint infection and clinically detectable junctional problems. The stem survival rate, with any stem revision as the endpoint, at 12 years was 96.6%. No significant difference was observed in the functional and radiological outcomes beween the Ti–Ti and nonmodular groups. Conclusions: The Ti–Ti modular neck femoral stem had comparable results with broadly used nonmodular femoral stems; hence, it can be a reliable option in primary total hip arthroplasty. However, in terms of the modularity itself of the modular neck femoral stem, whether the modular neck femoral stem is useful in uncomplicated primary total hip arthroplasty is unclear. [ABSTRACT FROM AUTHOR]

Background and Objectives: Total hip arthroplasty (THA) requires accurate implant placement to ensure optimal outcomes. In this study, the AR Hip navigation system, an imageless portable navigation tool using augmented reality (AR), was evaluated for measuring radiographic inclination (RI), anteversion (RA), leg lengthening (LL), and offset (OS) changes in supine and lateral decubitus THA. Notably, this is the first report to assess the accuracy of LL and OS measurements using AR technology. Methods: We analyzed 48 hips from primary THA patients: 17 in the supine (S) group and 31 in the lateral (L) group. RI, RA, LL, and OS were measured intraoperatively using AR Hip and postoperatively using Zed Hip 3D software (Version 18.0.0.0). The absolute errors and outlier rates (≥5° for RI/RA and ≥5 mm for LL/OS) were compared between groups. Results: The mean intraoperative RI values with AR Hip were 40.1 ± 0.6° (S), 40.2 ± 1.2° (L), and 40.1 ± 1.0° (total), while the postoperative RI values with Zed Hip were 39.7 ± 2.9° (S), 39.5 ± 2.5° (L), and 39.6 ± 2.6° (total). The absolute errors were 1.8 ± 1.7° (total), with no significant group differences (p = 0.957). For RA, the errors were 2.0 ± 1.2° (total) (p = 0.771). The LL errors were 2.3 ± 2.2 mm (total) (p = 0.271), and the OS errors were 3.5 ± 2.8 mm (total) (p = 0.620). The outlier rates for RI were 11.8% (S) and 3.2% (L); for RA, 0% (S) and 3.2% (L); for LL, 29.4% (S) and 6.5% (L) with a significant difference (p = 0.031); and for OS, 23.5% (S) and 25.8% (L). No significant differences were observed for RI, RA, or OS. Conclusions: AR Hip provided accurate measurements of cup orientation, LL, and OS in both supine and lateral THA. Importantly, this study is the first to report the accuracy of LL and OS measurements using AR technology, demonstrating the potential of AR Hip for improving THA precision.

Objective During total hip arthroplasty (THA), both pelvic and femur positions affect leg length (LL) and offset (OS) measurements because LL and OS calipers depend on the fixed reference points on the pelvis and femur, respectively. However, LL and OS measurement errors because of pelvic positional changes have not been described. This study aimed to clarify the effects of pelvic positional changes on LL and OS measurements in relation to the pelvic reference using a THA simulator. Methods We developed an experimental THA simulator using Sawbones models of the hemipelvis and femur that facilitated modification of the obliquity, tilt, and rotation of the pelvis. Using an LL and OS caliper, LL and OS measurement errors due to pelvic positional changes were determined with the femoral position fixed. Measurements were performed from two pelvic reference positions: the iliac tubercle (P1) and the top of the iliac crest intersecting the line of the femoral long axis (P2). Results Concerning pelvic obliquity, the total error of LL was 25.0 mm in P1 and 26.5 mm in P2, while the total error of OS was 13.0 mm in P1 and 10.9 mm in P2. For pelvic tilt, the total error of LL was 9.0 mm in P1 and 3.8 mm in P2, while the total error of OS was 0.5 mm in P1 and 1.0 mm in P2. Regarding pelvic rotation, the total error of LL was 13.8 mm in P1 and 3.2 mm in P2, while the total error of OS was 3.8 mm in P1 and 4.0 mm in P2. Conclusions Pelvic positional changes alter LL and OS measurements. The acceptable range (error

• Offsets in the frontal plane are important for hip function. • Research on total hip arthroplasty (THA) surgery agrees that increasing femoral offset up to 5 mm could improve functional outcome measures. • The literature indicates that global offset is a key parameter that physicians should restore within 5 mm during surgery and avoid decreasing. • Substantiated findings on acetabular offset are lacking despite its recognized importance, and the medialization approach must be assessed in light of its shortcomings. • Future research, possibly through improved measurement, unified definitions, patientspecific surgical planning, and technology-enhanced surgical control, with specific focus on acetabular offset, is needed to better understand its impact on THA outcomes.

Objective: During total hip arthroplasty (THA), both pelvic and femur positions affect leg length (LL) and offset (OS) measurements because LL and OS calipers depend on the fixed reference points on the pelvis and femur, respectively. However, LL and OS measurement errors because of pelvic positional changes have not been described. This study aimed to clarify the effects of pelvic positional changes on LL and OS measurements in relation to the pelvic reference using a THA simulator. Methods: We developed an experimental THA simulator using Sawbones models of the hemipelvis and femur that facilitated modification of the obliquity, tilt, and rotation of the pelvis. Using an LL and OS caliper, LL and OS measurement errors due to pelvic positional changes were determined with the femoral position fixed. Measurements were performed from two pelvic reference positions: the iliac tubercle (P1) and the top of the iliac crest intersecting the line of the femoral long axis (P2). Results: Concerning pelvic obliquity, the total error of LL was 25.0 mm in P1 and 26.5 mm in P2, while the total error of OS was 13.0 mm in P1 and 10.9 mm in P2. For pelvic tilt, the total error of LL was 9.0 mm in P1 and 3.8 mm in P2, while the total error of OS was 0.5 mm in P1 and 1.0 mm in P2. Regarding pelvic rotation, the total error of LL was 13.8 mm in P1 and 3.2 mm in P2, while the total error of OS was 3.8 mm in P1 and 4.0 mm in P2. Conclusions: Pelvic positional changes alter LL and OS measurements. The acceptable range (error <2 mm) on LL and OS measurement errors of pelvic obliquity was only 2°, regardless of the pelvic reference position. The pelvic reference position should be at the top of the iliac crest intersecting the line of the long axis of the femur because of a small LL measurement error with pelvic tilt and rotation. [ABSTRACT FROM AUTHOR]

Conflicting reports exist about the effect of offset variation on functional outcomes following total hip arthroplasty. Reproducing native hip offset is thought to optimize function by restoring biomechanics and appropriately tensioning the hip abductor muscles. The aim of this study is to assess the effect of failing to restore global hip offset in comparison to the native contralateral hip. A retrospective analysis of a prospective patient cohort was performed on patients undergoing an elective primary total hip arthroplasty. A total of 414 patients who had a minimum of 12 months of follow-up were included. Postoperative plain radiographs were analyzed for offset and compared to the contralateral native hip. Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Veterans RAND 12 (VR-12) scores were assessed preoperatively and at 12 months postoperatively. Regression analyses indicated that a reduction in offset of >20 mm resulted in worse WOMAC pain (P =.005) and motion (P =.015) scores compared to those with maintained offset. WOMAC function (P =.063), global (P =.025), and VR-12 scores were not affected (physical P =.656; mental P =.815). Reduction in offset up to 20 mm and increased offset were not significantly associated with patient-reported outcome measures (P -values ranged from.102 to.995). This study demonstrated an association between reduction in offset by >20 mm and worse WOMAC pain and motion scores following total hip arthroplasty. Surgeons should avoid decreases in offset >20 mm in order to optimize functional outcomes. [ABSTRACT FROM AUTHOR]

Abstract Background Although the high offset Tri-Lock bone preservation stem (BPS) was used widely, few studies explored the clinical and radiological results. The purpose of this study was to determine the clinical and radiological results of high offset Tri-Lock BPS in unilateral primary total hip arthroplasty (THA) at a minimum follow-up of 3 years. Methods 55 patients who underwent cementless THA with high offset Tri-lock BPS from 2017 to 2018 were followed for a minimum follow-up of 3 years. Patients were assessed clinically for complications, Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Oxford Hip Score (OHS). Femoral offset (FO), acetabular offset (AO), hip offset (HO), HO difference, and leg length discrepancy (LLD) were measured on the anteroposterior (AP) pelvic radiograph. Standard pelvic AP and lateral radiographs were used to evaluate for evidence of bone ingrowth, stem subsidence, stem alignment, radiolucent line around the stem, osteolysis, loosening, ectopic ossification, and femoral stress shielding. Results No patients reported complications during hospitalization nor the follow-up period. At a mean follow-up of 42.5 months, the mean HHS, WOMAC, and OHS scores showed a significant improvement from preoperative to the latest follow-up. No patients reported thigh pain. No revision nor sign of radiographic loosening had been detected. The high offset Tri-Lock BPS significantly improved the FO and HO postoperatively. HO difference and LLD were balanced postoperatively. No sign of stem subsidence, radiolucent line, osteolysis, loosening, ectopic ossification, nor severe stress shielding (more than grade 3–4) were observed at the latest follow-up. Conclusion The high offset Tri-Lock BPS demonstrated excellent clinical and radiographic outcomes at a minimum follow-up of 3 years. HO difference and LLD between legs decreased significantly and achieved balance postoperatively. Long-term follow-up is required for a definitive conclusion.

Background: Although component offset can affect impingement after total hip arthroplasty, the exact impact is unclear. Evaluation of offset on an anterior-posterior pelvic radiograph is different than evaluation in functional positions of impingement, namely flexion/internal rotation and extension/external rotation. We quantified the effect of acetabular (cup/liner) vs femoral (head/stem) offsets on changes in range of motion to extra-prosthetic impingement in these 2 impingement-prone functional positions.Methods: We retrospectively identified 16 total hip arthroplasty patients (age 61.5 ± 12.1 years, body mass index 28.3 ± 4.9 kg/m2) with preoperative and postoperative computerized tomography scans. To eliminate metal artifact, femoral and pelvic 3-dimensional models were created using preoperative scans aligned with postoperative scans, and 3-dimensional scanned implant models were used to reproduce clinical implantation. We tested ±5 mm acetabular cup, acetabular liner, femoral stem, and femoral head offsets. Maximum range of motion (ROM) to bone-bone impingement was calculated for internal rotation at 90° flexion and external rotation at 10° extension.Results: In all cases, increased offset increased ROM to impingement, and vice versa. During internal rotation at 90° flexion, ±5 mm liner offset had the greatest impact on ROM (+9°/-10°), followed by cup (+8°/-9°), head (+5°/-7°), and stem (+3°/-5°) offset. During external rotation at 10° extension, ±5 mm cup offset had the greatest impact on ROM (+10°/-10°), followed by liner (+9°/-9°), head (+7°/-8°), and stem (+4°/-4°) offset. However, no statistically significant differences were found in the changes to ROM in flexion obtained through cup and liner offsets, the changes to ROM in extension obtained through liner and head offsets, and the changes to ROM in extension obtained through increasing stem and head offsets.Conclusion: Increasing offset by any method reduces impingement. Center-of-rotation offset changes via acetabular cup or liner have the greatest impact on extra-prosthetic impingement. [ABSTRACT FROM AUTHOR]

Abstract Background Leg length (LL) and offset (OS) are important factors in total hip arthroplasty (THA). Because most LL and OS callipers used in THA depend on fixed points on the pelvis and the femur, limb position could affect measurement error. This study was conducted on a THA simulator to clarify the effects of lower limb position and iliac pin position on LL and OS errors and to determine the permissible range of limb position for accurate LL and OS measurement. Methods An LL and OS measurement instrument was used. Two pin positions were tested: the iliac tubercle and the top of the iliac crest intersecting with the extension of the femoral axis. First, the limb was moved in one direction (flexion-extension, abduction-adduction, or internal-external rotation), and LL and OS were measured for each pin position. Next, the limb was moved in combinations of the three directions. Then, the permissible range of combined limb position, which resulted in LL and OS measurement error within ±2 mm, was determined for each pin position. Results Only 4° of abduction/adduction caused 5–7 mm error in LL and 2–4 mm error in OS, irrespective of pin position. The effects of flexion–extension and internal–external rotation on LL error were smaller for the top of the iliac crest than for the iliac tubercle, though OS error was similar for both pin positions. For LL, the permissible range of the combined limb position was wider for the top of the iliac crest than for the iliac tubercle. Conclusion To minimize LL and OS measurement errors in THA, adduction–abduction must be maintained. The iliac pin position in the top of the iliac crest is preferred because it provides less LL measurement error and a wider permissible range of combined limb position for accurate LL measurement.

Hip arthroplasty is a common procedure in elective orthopaedic surgery that has excellent outcomes. Hip replacement surgery aims to create a "forgotten" joint, i.e., a pain-free joint akin to a native articulation. To achieve such goals, hip arthroplasty must be personalised. This is achieved by restoring: the centre of rotation of the native hip; leg length equality; femoral offset; femoral orientation; soft tissue tension; joint stability with an unrestricted hip range of motion; and having appropriate stress transfer to the bone. In addition, the whole pathway should provide an uneventful and swift postoperative recovery and lifetime implant survivorship with unrestricted activities. At our institution, the preferred option is a personalized total hip arthroplasty (THA) with a large diameter head (LDH) using either monobloc or dual-mobility configuration for the acetabular component. LDH THA offers an impingement-free range of motion and a reduced risk of dislocation. The larger head-neck offset allows for a supraphysiologic range of motion (ROM). This can compensate for a patient's abnormal spinopelvic mobility and surgical imprecision. Additionally, LDH bearing with a small clearance exerts a high suction force, which provides greater hip micro-stability. With appropriate biomechanical reconstruction, LDH THA can restore normal gait parameters. This results in unrestricted activities and higher patient satisfaction scores. We use LDH ceramic on ceramic for our patients with a life expectancy of more than 20 years and use LDH dual mobility bearings for all others. [ABSTRACT FROM AUTHOR]

Abstract Background A proper restoration of hip biomechanics is fundamental to achieve satisfactory outcomes after total hip arthroplasty (THA). A global hip offset (GO) postoperatively reduction of more than 5 mm was known to impair hip functionality after THA. This study aimed to verify the restoration of the GO radiographic parameter after primary THA by the use of a cementless femoral stem available in three different offset options without length changing. Methods From a consecutive series of 201 patients (201 hips) underwent primary cementless THA in our center with a minimum 3-year follow up, 80 patients (80 hips) were available for complete radiographic evaluation for GO and limb length (LL) and clinical evaluation with Harris hip score (HHS). All patients received the same femoral stem with three different offset options (option A with – 5 mm offset, option B and option C with + 5 mm offset, constant for each sizes) without changing stem length. Results Mean GO significantly increased by + 3 mm (P

Background: Although the high offset Tri-Lock bone preservation stem (BPS) was used widely, few studies explored the clinical and radiological results. The purpose of this study was to determine the clinical and radiological results of high offset Tri-Lock BPS in unilateral primary total hip arthroplasty (THA) at a minimum follow-up of 3 years. Methods: 55 patients who underwent cementless THA with high offset Tri-lock BPS from 2017 to 2018 were followed for a minimum follow-up of 3 years. Patients were assessed clinically for complications, Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Oxford Hip Score (OHS). Femoral offset (FO), acetabular offset (AO), hip offset (HO), HO difference, and leg length discrepancy (LLD) were measured on the anteroposterior (AP) pelvic radiograph. Standard pelvic AP and lateral radiographs were used to evaluate for evidence of bone ingrowth, stem subsidence, stem alignment, radiolucent line around the stem, osteolysis, loosening, ectopic ossification, and femoral stress shielding. Results: No patients reported complications during hospitalization nor the follow-up period. At a mean follow-up of 42.5 months, the mean HHS, WOMAC, and OHS scores showed a significant improvement from preoperative to the latest follow-up. No patients reported thigh pain. No revision nor sign of radiographic loosening had been detected. The high offset Tri-Lock BPS significantly improved the FO and HO postoperatively. HO difference and LLD were balanced postoperatively. No sign of stem subsidence, radiolucent line, osteolysis, loosening, ectopic ossification, nor severe stress shielding (more than grade 3–4) were observed at the latest follow-up. Conclusion: The high offset Tri-Lock BPS demonstrated excellent clinical and radiographic outcomes at a minimum follow-up of 3 years. HO difference and LLD between legs decreased significantly and achieved balance postoperatively. Long-term follow-up is required for a definitive conclusion. [ABSTRACT FROM AUTHOR]

Background: Leg length (LL) and offset (OS) are important factors in total hip arthroplasty (THA). Because most LL and OS callipers used in THA depend on fixed points on the pelvis and the femur, limb position could affect measurement error. This study was conducted on a THA simulator to clarify the effects of lower limb position and iliac pin position on LL and OS errors and to determine the permissible range of limb position for accurate LL and OS measurement. Methods: An LL and OS measurement instrument was used. Two pin positions were tested: the iliac tubercle and the top of the iliac crest intersecting with the extension of the femoral axis. First, the limb was moved in one direction (flexion-extension, abduction-adduction, or internal-external rotation), and LL and OS were measured for each pin position. Next, the limb was moved in combinations of the three directions. Then, the permissible range of combined limb position, which resulted in LL and OS measurement error within ±2 mm, was determined for each pin position. Results: Only 4° of abduction/adduction caused 5–7 mm error in LL and 2–4 mm error in OS, irrespective of pin position. The effects of flexion–extension and internal–external rotation on LL error were smaller for the top of the iliac crest than for the iliac tubercle, though OS error was similar for both pin positions. For LL, the permissible range of the combined limb position was wider for the top of the iliac crest than for the iliac tubercle. Conclusion: To minimize LL and OS measurement errors in THA, adduction–abduction must be maintained. The iliac pin position in the top of the iliac crest is preferred because it provides less LL measurement error and a wider permissible range of combined limb position for accurate LL measurement. [ABSTRACT FROM AUTHOR]

Background: Spinal stiffness has been shown to increase risk of dislocation due to impingement and instability. Increasing anteversion of the acetabular component has been suggested to prevent dislocation, but little has been discussed in terms of femoral or global offset restoration. The purpose of this study is to quantify dislocation rates after primary THA using standard versus high-offset femoral components and to determine how differences in offset affect impingement-free range of motion in a stiff spine cohort using a novel impingement model.Methods: A total of 12,365 patients undergoing THA from 2016 to 2018 were retrospectively reviewed to determine dislocation rates and utilization of standard- versus high-offset stems. For 50 consecutive patients with spinal stiffness, a CT-based computer software impingement modeling system assessed bony or prosthetic impingement during simulated range of motion. The model was run 5 times for each patient with varying offsets. Range of motion was simulated in each scenario to determine the degree at which impingement occurred.Results: There were 51 dislocations for a 0.41% dislocation rate. Total utilization of high-offset stems in the entire cohort was 49%. Of those patients who sustained a dislocation, 49 (96%) utilized a standard-offset stem. The impingement modeling demonstrated 5 degrees of added range of motion until impingement for every 1 mm offset increase.Conclusion: In the impingement model, high-offset stems facilitated greater ROM before bony impingement and resulted in lower dislocation rates. In the setting of high-risk THA due to spinal stiffness, surgeons should consider the use of high-offset stems and pay attention to offset restoration. [ABSTRACT FROM AUTHOR]

Background: A proper restoration of hip biomechanics is fundamental to achieve satisfactory outcomes after total hip arthroplasty (THA). A global hip offset (GO) postoperatively reduction of more than 5 mm was known to impair hip functionality after THA. This study aimed to verify the restoration of the GO radiographic parameter after primary THA by the use of a cementless femoral stem available in three different offset options without length changing.Methods: From a consecutive series of 201 patients (201 hips) underwent primary cementless THA in our center with a minimum 3-year follow up, 80 patients (80 hips) were available for complete radiographic evaluation for GO and limb length (LL) and clinical evaluation with Harris hip score (HHS). All patients received the same femoral stem with three different offset options (option A with - 5 mm offset, option B and option C with + 5 mm offset, constant for each sizes) without changing stem length.Results: Mean GO significantly increased by + 3 mm (P < 0.05) and mean LL significantly decreased by + 5 mm (P < 0.05) after surgery, meaning that postoperatively the limb length of the operated side increased by + 5 mm. HHS significantly improved from 56.3 points preoperatively to 95.8 postoperatively (P < 0.001). Offset option A was used in 1 hip (1%), B in 59 hips (74%) and C in 20 hips (25%).Conclusions: The femur is lateralized with a mean of + 5 mm after surgery than, the native anatomy, whatever type of stem was used. Thus, the use of this 3-offset options femoral stem is effective in restoring the native biomechanical hip parameters as GO, even if 2 offset options were considered sufficient to restore GO. [ABSTRACT FROM AUTHOR]

Background: Achieving appropriate limb length and offset in total hip arthroplasty (THA) is challenging. Target limb length and offset may not always mean equal radiographic measurements bilaterally. The goal of this study is to introduce a method for determining as well as achieving target limb length and offset using digital radiographic measurements.Methods: One hundred and two consecutive patients with unilateral hip osteoarthritis undergoing primary THA in the lateral decubitus position were included. Limb length and offset were measured on anterior-posterior pelvic radiographs preoperatively, intraoperatively, and postoperatively. Offset was defined as the length of a line parallel to the inter-teardrop line, extending from the edge of the ischium, at about the lower border of the ipsilateral obturator foramen, to the edge of the femoral cortex, usually at, or just below, the neck resection level. Target limb length was determined for each patient based on patient perception and severity of disease. Target offset equaled the contralateral limb. Using intraoperative digital radiography, adjustments were made until targets were achieved and the hip was stable. Patients were followed for an average of 4.2 years postoperatively.Results: Limb length was within 5 mm of target measurements in 100% of patients and offset was within 5 mm of targets in 97.1%. Target measurements differed by >5 mm from the contralateral side in 2.0% of limb length and 2.9% of offset measurements. There were no significant differences between intraoperative and postoperative limb length (P = .261) or offset (P = .747) measurements. At final follow-up, there were no dislocations or reoperations and average Hip disability and Osteoarthritis Outcome Score for Joint Replacement was 95.78.Conclusion: Target limb length and offset goals can be determined for most patients undergoing THA. Targets are not always equal to the contralateral side. Intraoperative digital radiography can allow surgeons to accurately achieve target limb length and offset to within 5 mm in a homogenous cohort of patients with unilateral hip osteoarthritis with excellent clinical outcomes. [ABSTRACT FROM AUTHOR]

Restoring native hip anatomy and biomechanics is important to create a well-functioning hip arthroplasty. This study investigated the association of hip offset and leg length after hip arthroplasty with clinical outcomes, including patient reported outcome measures, the Trendelenburg Test and gait analysis. In 77 patients undergoing primary hip arthroplasty for osteoarthritis (age mean = 65 SD = 11 years; BMI mean = 27 SD = 5 kg/m2), hip offset and leg length discrepancy were measured on anteroposterior radiographs. The Western Ontario & McMaster Universities Osteoarthritis Index, the Trendelenburg Test and gait were assessed preoperatively, and at 3 and 12 months postoperatively. An inertial measurement unit was used to derive biomechanical parameters, including spatiotemporal gait parameters and tilt angles of the pelvis. Relationships between radiographic and functional outcomes were investigated, and subgroups of patients with >15% decreased and increased femoral offset were analysed separately. Patient-reported function scores and clinical tests demonstrated a few significant, weak correlations with radiographic outcomes (Spearman's ρ range = 0.26–0.32; p < 0.05). Undercorrection of femoral offset was associated with lower patient-reported function scores and with more step irregularity as well as step asymmetry during gait. Postoperative leg length inequality was associated with increased frontal plane tilt angle of the pelvis during the Trendelenburg Test and increased sagittal plane motion of the pelvis during gait. Femoral offset subgroups demonstrated no significant differences for patient-reported function scores and outcomes of the Trendelenburg Test and gait analysis. Reduced hip offset and leg length discrepancy following hip arthroplasty seem to be marginally associated with worse clinical outcomes. • Reduced offset after total hip arthroplasty results in worse patient-reported function. • Reduced offset following total hip arthroplasty causes gait irregularity and asymmetry. • Reduced offset following total hip arthroplasty alters outcomes the Trendelenburg Test. • Leg length discrepancy below 1 cm after total hip arthroplasty does not cause impaired function. [ABSTRACT FROM AUTHOR]

Wayne G Paprosky,1,2 Jeffrey M Muir3 1Department of Orthopedics, Section of Adult Joint Reconstruction, Department of Orthopedics, Rush University Medical Center, Rush–Presbyterian–St Luke’s Medical Center, Chicago, 2Central DuPage Hospital, Winfield, IL, USA; 3Intellijoint Surgical, Inc, Waterloo, ON, Canada Abstract: Total hip arthroplasty is an increasingly common procedure used to address degenerative changes in the hip joint due to osteoarthritis. Although generally associated with good results, among the challenges associated with hip arthroplasty are accurate measurement of biomechanical parameters such as leg length, offset, and cup position, discrepancies of which can lead to significant long-term consequences such as pain, instability, neurological deficits, dislocation, and revision surgery, as well as patient dissatisfaction and, increasingly, litigation. Current methods of managing these parameters are limited, with manual methods such as outriggers or calipers being used to monitor leg length; however, these are susceptible to small intraoperative changes in patient position and are therefore inaccurate. Computer-assisted navigation, while offering improved accuracy, is expensive and cumbersome, in addition to adding significantly to procedural time. To address the technological gap in hip arthroplasty, a new intraoperative navigation tool (Intellijoint HIP®) has been developed. This innovative, 3D mini-optical navigation tool provides real-time, intraoperative data on leg length, offset, and cup position and allows for improved accuracy and precision in component selection and alignment. Benchtop and simulated clinical use testing have demonstrated excellent accuracy, with the navigation tool able to measure leg length and offset to within

Introducción: El objetivo de este estudio retrospectivo fue observar el comportamiento de un tallo modular de fijación proximal y anclaje distal en revisiones de cadera con defectos femorales II y IIIA (Praposky), evaluando la estabilidad protésica y articular, la restauración del off-set y la discrepancia de longitud. Materiales: Analizamos 22 RRTC de los cuales 12 (56,5%) fueron mujeres y 10 varones con un promedio de edad de 62,38 años. El seguimiento promedio fue de 62 meses. El tallo femoral utilizado fue el S-ROM ® (Depuy – J&J). Los defectos óseos femorales fueron 15 tipo II y 7 IIIA de Praposky. Para la evaluación clínica se utilizó el Score de cadera de Harris (HHS). Radiológicamente se analizó el comportamiento del tallo, su integración, la discrepancia de longitud y el off-set femoral, considerándose como correcto una diferencia menor a 5mm. Resultados: el offset fue restaurado en 16 (72,3%) casos y la longitud de miembros se restauró en 15 (68,2%). Hubo un solo hundimiento del tallo, y de acuerdo con Engh se observaron 17 (77,27%) uniones óseas. Hubieron 7 (31,8%) complicaciones, 2 luxaciones que requirieron revisión, 4 fracturas intra-operatorias y una paresia de CPE. Conclusión este tallo impresiona ser una alternativa valida para resolver un problema complejo. Por su versatilidad, permite resolver mecánicamente el defecto óseo, devuelve la longitud al miembro y el off set a la articulación, presentando un índice de complicaciones aceptables.

Abstract Introduction Total hip arthroplasty (THA) has been termed as 'operation of the century' as it provides a stable and mobile hip to patients who are debilitated by pathologies affecting the hip. Acetabular fractures pose a challenge for their initial management as well for the management of secondary osteoarthritis which is often the outcome of these fractures. The study attempts to evaluate the short term radiological, functional and quality of life outcomes of THA done in patients with prior acetabular fractures and to find a correlation between various factors. Materials and methods 47 patients who provided consent for this retrospective study were clinically and radiologically evaluated at their latest follow up. Ratios of horizontal offset, vertical offset, body lever arm and cup inclination were calculated with respect to the opposite normal hip on a radiograph. Questionnaires were filled up for Harris Hip Score (HHS), Short form -12, Short Musculoskeletal functional assessment (SMFA) and WHO-quality of life (WHO-QoL). Results HHS and quality of life scores had a tendency to improve over time. A statistically significant difference (p < 0.05) was noted between scores of patients having less than 2 years follow up and more than 4 years follow-up. The HHS, radiological and quality of life parameters were not statistically significantly different when analysed based on acetabular fracture pattern, their primary management and aetiology necessitating the THA. Conclusion The short term radiological, functional and quality of life parameters are dependent on the accuracy of the THA performed and are not significantly affected by the fracture type, initial management and outcomes of that management. However, longer follow up is necessary to evaluate these parameters even more accurately. [ABSTRACT FROM AUTHOR]

Background: There is a lack of prospective studies investigating the additive effect of both acetabular and femoral reconstruction parameters on the functional outcome following total hip arthroplasty (THA).Methods: The aim of this prospective cohort study was to determine the combined influence of hip geometry reconstruction and component positioning on the clinical outcome following primary THA for unilateral osteoarthritis. We prospectively assessed the clinical outcome and radiographic parameters for hip geometry reconstruction, component position, and orientation using validated measurements for the operated hip compared to the contralateral native hip in a consecutive series of 113 patients with primary unilateral cementless THA. The correlation of reconstruction parameters was investigated using a multivariate polynomial regression model for the dependent variable ΔHHS (difference between the Harris hip scores preoperatively and 2.0-4.8 years postoperatively). Target zones for hip reconstruction and component positioning were investigated for an association with superior clinical outcome.Results: The regression model demonstrated a significant correlation for the ΔHHS and both hip offset (HO) reconstruction and leg length difference. Patients with accurate to slightly increased HO reconstruction combined with balanced leg length demonstrated a significantly higher ΔHHS than patients outside this zone (HO: 5 ± 5 and LLD: 0 ±5 mm, P = .029). This finding could be confirmed for 2 enlarged zones (zone 1: HO, 7.5 ± 7.5 and LLD, 2.5 ± 7.5 mm, P = .028; zone 2: HO, 7.5 ± 7.5 and LLD, 7.5 ± 7.5 mm, P = .007).Conclusion: HO and leg length reconstruction demonstrated an additive effect on clinical outcome and surgeons should aim for high accuracy in the reconstruction of both factors. [ABSTRACT FROM AUTHOR]

Introduction: Modern total hip arthroplasty is largely dependent on the successful preservation of hip geometry. Thus, a successful implementation of the preoperative planning is of great importance. The present study evaluates the accuracy of anatomic hip reconstruction predicted by 2D digital planning using a calcar-guided short stem of the newest generation. Methods: A calcar-guided short stem was implanted in 109 patients in combination with a cementless cup using the modified anterolateral approach. Preoperative digital planning was performed including implant size, caput-collum-diaphyseal angle, offset, and leg length using mediCAD II software. A coordinate system and individual scale factors were implemented. Postoperative outcome was evaluated accordingly and was compared to the planning. Results: Intraoperatively used stem sizes were within one unit of the planned stem sizes. The postoperative stem alignment showed a minor and insignificant ( p = 0.159) mean valgization of 0.5° (SD 3.79°) compared to the planned caput-collum-diaphyseal angles. Compared to the planning, mean femoral offset gained 2.18 (SD 4.24) mm, while acetabular offset was reduced by 0.78 (SD 4.36) mm during implantation resulting in an increased global offset of 1.40 (SD 5.51) mm ( p = 0.0094). Postoperative femoroacetabular height increased by a mean of 5.00 (SD 5.98) mm ( p < 0.0001) compared to preoperative measures. Discussion: Two-dimensional digital preoperative planning in calcar-guided short-stem total hip arthroplasty assures a satisfying implementation of the intended anatomy. Valgization, which has been frequently observed in previous short-stem designs, negatively affecting offset, can be avoided. However, surgeons have to be aware of a possible leg lengthening. [ABSTRACT FROM AUTHOR]

Purpose: Various methods exist for measuring limb length and lateralisation after total hip arthroplasty. Most of them utilise standard anteroposterior (AP) pelvic radiographs, but their results can be affected by patient position during imaging and thus the position of the lower limb on the coronal plane. The aim of this study is to evaluate how commonly used measuring methods of limb lengthening and femoral offset are affected by the position of the lower limb in the coronal plane.Methods: A standing pelvic AP radiograph post implantation of a right total hip prosthesis was digitised. The right femur and its femoral stem were digitally segmented, such that they could be positioned orthogonal to the pelvis horizontal reference, with 10° of adduction, and with 10° of abduction, with respect to the centre of rotation. Various limb lengths and implant lateralisation were also digitised. We obtained nine x-rays differing one to three variables. Twice four independent surgeons performed three femoral length measurement methods and femoral offset measurement methods. Intra and inter-observer error as well as the effect of the femoral position on the measurements were studied.Results: With respect to length measurements, the distance between the centre of rotation (C) and the tip of the lesser trochanter (LT) increased by 3 mm per cm of lateralisation. This measurement was not affected by the hip position in abduction or adduction. The distance between the tip of the lesser or greater trochanter (GT) and the horizontal passing through the centre of rotation was strongly affected by the hip position in abduction or adduction. With respect to offset, the distance between the centre of rotation and the greater trochanter (C-GT) was the most consistent and was not affected by variations in lengths or femoral axis. At the level of the lesser trochanter, the distance of the femoral anatomical axis and to Perkin's line was heavily influenced by the femoral position.Conclusion: The C-LT distance was consistent in measuring limb length and the C-GT distance was reliable in determining femoral offset regardless of the relative position of the femur. [ABSTRACT FROM AUTHOR]

Background: Predisposing factors for trunnionosis and elevated metal ion levels in metal-on-polyethylene (MOP) total hip arthroplasty (THA) are currently unknown.Methods: This retrospective cohort study enrolled 80 consecutive patients (43 males) with an asymptomatic MOP THA at 2- to 5-year follow-up and no other metal implants. Serum cobalt (Co) and chromium (Cr) levels were collected at the time of enrollment, and retrospective review was performed regarding demographic, implant, and surgical characteristics. Mean age at the time of surgery was 65.7 years (range 35.6-85.9 years), and mean postoperative follow-up was 28.7 months (range 24.4-58.9 months).Results: Femoral head offset was the only evaluated factor shown to increase serum Co ion levels above baseline within the cohort. Mean difference in Co level for high and low offset implants was 0.58 ppb (95% confidence interval [CI] = 0.05-1.11 ppb; P = .03). Mean difference in Cr level for high and low offset implants was 0.19 ppb (95% CI = -0.23 to 0.60 ppb; P = .37). Mean difference in Co level for small and large femoral heads was 0.20 ppb (95% CI = -0.41 to 0.81 ppb; P = .59). Mean difference in Cr level for small and large femoral heads was 0.28 ppb (95% CI = -0.18 to 0.74 ppb; P = .06). Age, gender, Harris Hip Score, and implant duration were not associated with changes in metal ion levels.Conclusion: Femoral head offset appears to be an important source of elevated metal ion levels in MOP THA. Further studies will be needed to understand if increasing femoral head offset is associated with subsequent adverse local tissue reactions. [ABSTRACT FROM AUTHOR]

Background: The morphologic features of the proximal femur are used in preoperative planning prior to total hip arthroplasty. The standard commercially available marketed prostheses sometimes may not be the best fit to all subjects because of the large anatomic variation among different population. Orthopaedic surgeons always stress the need for a proper implant-patient match in hip joint replacements to avoid postoperative complication of mismatch which may affect the ultimate outcome of the operation. Aim: The present study was undertaken to measure the important parameters of upper end of femur in elderly Eastern Indian population which will help the prosthetist to manufacture ideal implant for the local population. This will also help the orthopaedic surgeons while positioning the implants during total hip replacement (THR) procedure in this population. Materials and Methods: Measurements were made on both sides, left and right from anterior-posterior radiograph of 102 subject (>50yrs, 42 male and 60 females) using AGFA software. Three parameters femoral head diameter (FHD), neck-shaft angle (NSA) and horizontal off-set (HO) were measured. Results: SPSS software used for data analysis. Gender- wise no significant differences were found in NSA and FHD, but HO was significantly lower in female than that of male (p

Purpose: To evaluate the influence of stem offset and neck shaft angles on the range of motion before component impingement (ROMCI) and bony impingement (ROMBI), and the types of impingement in total hip arthroplasty (THA).Methods: Using the computed tomography data of 101 patients who underwent THA, three-dimensional dynamic motion analysis was performed using a modular implant (Kinectiv(®) stem) that enabled adjustment of offset and leg length independently. We defined offset as horizontal offset (HO) and leg length as vertical offset (VO), and measured the ROMCI and ROMBI in flexion (Flex), internal rotation (Int-R) and external rotation (Ext-R) with the configuration of each horizontal/vertical offset.Results: We found that HO lengthening increased the ROMCI and ROMBI in Flex and Int-R by delaying bony impingement, although excessive lengthening had minimal effect. On the contrary, VO lengthening decreased the ROMCI and ROMBI in Flex and ROMCI in Int-R. As for Ext-R, VO lengthening had positive effects on the ROMCI and ROMBI, whereas lengthening of HO had negative effects on the ROMCI and ROMBI.Conclusions: We demonstrated that the appropriate long offset with a low shaft angle increased the ROM in Flex and Int-R, and a high neck shaft angle increased the ROM in Ext-R. We should use implants properly in accordance with the types of impingement for avoiding dislocations in THA. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to quantify the femoral canal diameter and version at different femoral neck osteotomy locations, and to investigate the effect of the osteotomy plane on femoral component position in total hip arthroplasty (THA).Methods: Preoperative and postoperative three-dimensional models were reconstructed in 15 patients (19 hips) who underwent primary cementless THA with tapered non-anatomical femoral stem. On the pre-operative models, the osteotomy plane was simulated at different levels (-5, 0, 5, and 10 mm from the femoral saddle [piriformis fossa]) and angles (30, 40, 50, and 60° from the femoral anatomical axis). Medullary canal version and mediolateral diameter were measured on the osteotomy surfaces. On the postoperative models, the femoral neck osteotomy plane, stem anteversion and alignment were measured.Results: The average canal diameter ranged from 22.8 to 26.3 mm at different osteotomy levels and from 20.8 to 29.0 mm at different osteotomy angles. The average canal version ranged from 11.4 to 23.2° at different resection levels and from 12.8 to 21° at different resection angles. The femoral stem anteversion was correlated with neck osteotomy angle (R = 0.72), whereas stem alignment in frontal plane (varus/valgus) was correlated with neck osteotomy level (R = 0.87).Conclusions: The femoral neck osteotomy plane in THA affects the postoperative stem position due to the complex morphology of the proximal femoral medullary canal, suggesting that both femoral neck resection level and angle should be considered in optimizing femoral component alignment in THA patients. [ABSTRACT FROM AUTHOR]

Abstract: This extensive radiographic study asks if there is a statistical relationship between the size of the stem that will best fit the femur and the vertical and lateral offsets of the reconstructed acetabular center, what is the distribution of vertical and lateral offsets in this large and if there is a statistical difference among surgeons in the planned location of the reconstructed acetabular center. On 466 radiographs, five surgeons separately templated stem size and acetabular cup location. The vertical and horizontal coordinates of the reconstructed acetabulum center were measured relative to the planned position of the stem. We found a strong correlation between the stem size and the average lateral and vertical offsets. Acetabular reaming associated with the anatomic variability of native femoral necks, leads to a span of 36mm in lateral offset, and a span of 39mm in vertical offset. Statistically significant differences were also found in the way surgeons plan acetabular reaming. [Copyright &y& Elsevier]

Abstract: Background: Anterior dislocation is one of the concerns of patients with posterior pelvic tilt undergoing total hip arthroplasty. This study aimed to evaluate the magnitude of posterior pelvic tilt constituting a risk for anterior dislocation by measuring the range of motion until impingement and dislocation under various pelvic tilt. Methods: Using a jig mounted prosthetic hip model, the ranges of external rotation at extension and internal rotation at flexion until reaching dislocation were tested. The site of impingement prior to dislocation was also recorded. Posterior pelvic tilt and the cup version were changed with 10° increments from 0° to 40° and from 10° retroversion to 30° anteversion, respectively. Effects of increasing femoral offset were also tested. We defined a required range of motion as having 30° external rotation at extension and 40° internal rotation at 90° flexion. Findings: External rotation decreased in a posterior pelvic tilt-dependent manner. In the case with more than 20° posterior pelvic tilt, available external rotation extended beyond required range with the cup anteversion of 20°. Decreasing cup anteversion improved external rotation, however, internal rotation decreased simultaneously. In the case with posterior pelvic tilt more than 20°, only cup anteversion with 0° or 10° satisfied the required range of motion. A +4mm horizontal offset improved external rotation by 10° with delaying bony impingement. Interpretation: More than 20° of posterior pelvic tilt may cause anterior instability and diminish the optimal range of cup version. Increasing the femoral offset improved external rotation without reducing internal rotation. [Copyright &y& Elsevier]

Improvements in bearing technology have resulted in a reduction in wear and larger femoral heads to reduce dislocation rates. We retrospectively reviewed 668 primary THAs (580 patients) inserted with 32 mm or 36 mm femoral heads (1/2003-6/2007) performed through a posterior approach with posterior repair. Patients received a questionnaire assessing instability and dislocations. We compared clinical and radiographic data between patients with and without dislocations. Follow-up averaged 3.4 years (range 2-6.6 years). The dislocation rate was 1.3% (9/668). Decreasing the combined postoperative offset (lateral offset + medial offset measurements) and using acetabular cups larger than 58 mm in outer diameter increased the risk of dislocation. A majority of the hips that dislocated had negative combined offset and abduction angles in the upper and lower quartiles of all hips studied. Appropriate positioning should be used to minimise dislocation risk in THAs inserted with large femoral heads. [ABSTRACT FROM AUTHOR]

Abstract: This report represents a 5- to 10-year follow-up of our initial 2- to 5-year data with this proximally hydroxyapatite-coated stem design (Secur-Fit, Stryker Orthopaedics, Mahwah, NJ). This is a retrospective review of a single surgeon''s consecutive cases. A total of 105 cases were available for complete review. The average follow-up was 6.7 years (60-123 months). All stems achieved bony ingrowth. Harris hip score and Oxford hip score averaged to 91 and 17, respectively, with no differences seen between the 132° and the 127° stem designs. Leg length measurements were considered equal side-to-side differences of 7 mm or less in 87% of cases: 82% of standard- and 92% of high-offset cases (P < .05). Four cases of osteolysis were identified and occurred only in patients with an elevated rim liner, implicating neck-liner impingement. The stem design performed exceedingly well over the course of this study. Having a high-offset option aids the surgeon in proper leg length management. [Copyright &y& Elsevier]

Abstract: This study defines normal bilateral variations in offset and hip center location on pelvic radiographs. The relationship of the femoral head center to the tip of the greater trochanter and that of offset to medullary canal diameter are also defined. Measurements of the offset, hip center location, height of the tip of the greater trochanter from the femoral head center, and medullary canal diameter were carried out on 100 normal pelvic radiographs. The offset of one hip was found to predict that of the contralateral hip to within 4.62 mm with 95% confidence. Their hip center locations differed by 6.3 mm. The tip of the greater trochanter was, on average, 8 mm higher than the femoral head center. Although offset generally increased with an increase in medullary canal diameter, frequent discrepancies occurred in their relationship. [Copyright &y& Elsevier]

Background: The morphologic features of the proximal femur are used in preoperative planning prior to total hip arthroplasty. The standard commercially available marketed prostheses sometimes may not be the best fit to all subjects because of the large anatomic variation among different population. Orthopaedic surgeons always stress the need for a proper implant-patient match in hip joint replacements to avoid postoperative complication of mismatch which may affect the ultimate outcome of the operation. Aim: The present study was undertaken to measure the important parameters of upper end of femur in elderly Eastern Indian population which will help the prosthetist to manufacture ideal implant for the local population. This will also help the orthopaedic surgeons while positioning the implants during total hip replacement (THR) procedure in this population. Materials and Methods: Measurements were made on both sides, left and right from anterior-posterior radiograph of 102 subject (>50yrs, 42 male and 60 females) using AGFA software. Three parameters femoral head diameter (FHD), neck-shaft angle (NSA) and horizontal off-set (HO) were measured. Results: SPSS software used for data analysis. Gender- wise no significant differences were found in NSA and FHD, but HO was significantly lower in female than that of male (p<.05).The values on both sides didn't differ significantly. Conclusion: Improved knowledge of the morphology of the proximal femora will assist the surgeon in restoring the geometry of the proximal femur during total hip arthroplasty and the data could be used as a guideline to design a more suitable implant for Eastern Indian population. [ABSTRACT FROM AUTHOR]