A Simple Method Using a PACS to Minimize Leg Length Discrepancy in Primary THA : A Method to Minimize Leg Length Discrepancy

We determined whether a PACS-based method (head-lesser trochanter distance [HLD]) better equalized leg length discrepancy (LLD) after primary THA than a conventional method. We retrospectively reviewed 312 patients (379 hips) with osteonecrosis or primary osteoarthritis who underwent primary cementless THA: 198 patients (240 hips) underwent THA using the HLD method, while the conventional group consisted of 114 patients (139 hips) in whom we measured with the method of McGee and Scott. We then compared the LLDs in the two groups. We observed no difference in the mean postoperative LLD. A higher percentage of patients in the HLD group had an LLD less than 6 mm: 81% vs 68% hips, respectively. HLD method decreases the possibility of an LLD over 6 mm after THA.     

A Report on Three Consecutive Cases using Computer Tomography 3D Preoperative Planning for Conversion of Arthrodesed Hips to Total Hip Replacements

Background

Conversion of an arthrodesed hip to a total hip arthroplasty (THA) is a technically demanding procedure with high complication rates. One important issue is that determining the amount of correction for a leg length discrepancy (LLD) can be difficult at the planning stage.

Questions/Purposes

The aim of this study is to assess the reliable use of computer tomography (CT)-based three-dimensional (3D) preoperative planning for the conversion of arthrodesed hips to THAs.

Patients and Methods

CT-based preoperative 3D planning was used to convert three arthrodesed hips to THAs. The efficacy of the planning was evaluated with postoperative radiographic measurements involving the amount of correction for LLD, position of components, difference between targeted and actual values, and ratio of the moment arms. The clinical assessment was performed with the Japanese Orthopaedic Association (JOA) hip score before and after THA.

Results

The mean amount of LLD correction and median LLD after THA were 16 mm (range, 15–17 mm) and 4 mm (range, 1–10 mm), respectively. The components were implanted close to the positions recommended by the preoperative simulation. The ratio of the moment arms indicated that the converted hips were reconstructed in a biomechanically correct manner. The implants for the conversion to THA were successfully positioned with respect to anatomy and functional outcome. The median JOA hip score improved from 50 points (range, 30–66 points) preoperatively to 79 points (range, 72–86 points) at the latest follow-up.

Conclusions

CT-based preoperative 3D planning could be a powerful guidance tool for conversion of arthrodesed hips to THAs.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-014-9423-7) contains supplementary material, which is available to authorized users.     

Predictors and Functional Implications of Change in Leg Length After Total Knee Arthroplasty

Background

Leg lengthening occurs in 83% of primary total knee arthroplasty (TKA). The effects of leg length discrepancy (LLD) on THA patients are well established. However, patient function and satisfaction associated with LLD after primary TKA has not been analyzed. This study aimed to quantify the magnitude of limb lengthening, identify radiographic and perceived LLD, and correlate these with predictive factors and functional outcomes in a series of TKA patients.

Digital templating facilitates accurate leg length correction in total hip arthroplasty

Digital templating of pre-operative radiographs is increasingly utilised by surgeons before total hip arthroplasty (THA) as part of an adequate preoperative preparation to minimise complications. Templating can accurately predict the required implant sizes but its use in facilitating correction of leg length discrepancy (LLD) has been underreported in the literature. We performed a retrospective analysis of a cohort of consecutive patients undergoing primary THA. A comparison was made of the implant sizes templated with actual sizes used. In addition, pre-operative leg-length discrepancy (LLD) was noted and compared with intra-operative measurement of LLD correction and post-operative LLD correction seen on postoperative radiographs, as measured by two independent observers. Statistical analysis was performed to investigate the correlation between pre- and postoperative measurements. Fifty nine patients that had primary THA were investigated, 42 with hybrid replacements, 17 with cemented replacements. Spearman's-rho 2-tailed correlation between templated and implanted femoral offset, stem size and acetabular cup size was 0.850, 0.709 and 0.834 respectively (p < 0.01 for all). Correlation between the pre-operative templated LLD and the measured post-operative corrected LLD was 0.841 (p < 0.01). No difference existed between hybrid and cemented hips or the presence or absence of a contralateral hip replacement. In this study, templating for THA was significantly accurate in predicting the required femoral and acetabular implant sizes. In addition, the correction of pre-operative LLD was accurately performed, as evidenced by measurement on post-operative films. The results of this study support the pre-operative digital templating of radiographs in total hip arthroplasty.     

Incidence and Risk Factors of Iliopsoas Tendinopathy After Total Hip Arthroplasty: A Radiographic Analysis of 1,602 Hips

BackgroundIliopsoas tendinopathy (IPT) can cause persistent groin pain and lead to dissatisfaction after total hip arthroplasty (THA). This study aimed to report the characteristics, incidences, risk factors, and treatment outcomes of IPT after THA.MethodsWe reviewed primary THAs performed at a single institution between January 2012 and May 2018. Clinical and radiographic analyses were performed on 1,602 THAs (1,370 patients). Patient characteristics, component sizes, inclination and anteversion angles, and antero-inferior cup prominence (≥8 millimeters (mm)), were compared between the groups with and without IPT. Changes in teardrop to lesser trochanter distance were measured to estimate changes in leg length and horizontal offset caused by THA. Logistic regression models were used to identify the risk factors for IPT. IPT was identified in 53 hips (3.3%).ResultsPatients with IPT had greater leg lengthening (12.3 versus 9.3 mm; P = .001) and higher prevalence of antero-inferior cup prominence (5.7 versus 0.4%; P = .002). There was no significant difference in inclination, anteversion, and horizontal offset change between the two groups. In multivariate analyses, greater leg lengthening, prominent acetabular cup, women, and higher body mass index were associated with IPT. All patients reported improvement in groin pain after arthroscopic tenotomy, while 35.7% with nonoperative management reported improvement (P < .001).ConclusionsSymptomatic IPT occurred in 53 (3.3%) of the 1,602 primary THAs. Our findings suggest that leg lengthening as well as prominent acetabular cup in THAs can be associated with the development of IPT. Arthroscopic tenotomy was effective in relieving groin pain caused by IPT.     

Obesity does not influence acetabular component accuracy when using a 3D optical computer navigation system

IntroductionImproper cup positioning and leg length discrepancy (LLD) are two of the most common errors following total hip arthroplasty (THA) and are associated with potentially significant consequences. Obesity is associated with increased risk of mechanical complications, including dislocations, which may be secondary to cup malposition and failure to restore leg length and offset. 3D Optical Camera computerassisted navigation (CAN) system may reduce the risk of component malposition and LLD with real time intraoperative feedback. The aim of this study was to investigate whether the use of CAN influences acetabular component placement (CP) accuracy and leg length restoration in obese (body mass index(BMI)≥35kg/m 2 ) patients undergoing primary THA.MethodsA multi-center retrospective review was conducted identifying consecutive THA cases with BMI > 35kg/m 2 using CAN (Intellijoint Hip, Waterloo, CA) from 2015-2019. These patients were then matched with patients undergoing conventional THA (control) at a 1:1 ratio according to BMI, American Society of Anesthesiologists score, and gender. TraumaCad™ software (Brainlab, Chicago, IL) was used to measure cup anteversion, inclination, and change (Δ) in LLD between pre- and postoperative radiographic images. The safety target zones used as reference for precision analysis of CP were 15°-30° for anteversion and 30°-50° for inclination.Results176 patients were included: 88 CAN and 88 control cases. CAN cases were found to have a lower ΔLLD than controls (3.53±2.12mm vs. 5.00±4.05mm; p=0.003). Additionally, more CAN cases fell within the target safe zone than controls (83% vs.60%, p=0.00083).ConclusionOur findings suggest that the use of a CAN system may be more precise in component placement, and useful in facilitating the successful restoration of preoperative leg length following THA than conventional methodology.     

Subtrochanteric shortening osteotomy combined with cemented total hip arthroplasty for Crowe group IV hips

Background

Total hip arthroplasty (THA) is a challenging surgical procedure that can be used to treat severely dislocated hips. There are few reports regarding cemented THAs involving subtrochanteric shortening osteotomy (SSO), even though cemented THAs provide great advantages because the femur is generally hypoplastic with a narrow, deformed canal.

Purposes

We evaluated the utility of cemented THA with SSO for Crowe group IV hips, and assessed the relationship between leg lengthening and nerve injury. Our goal was to describe surgical techniques for optimizing surgical outcomes while minimizing the risk of nerve injury.

Methods

We retrospectively reviewed 34 cases of cemented THAs with transverse SSO for Crowe group IV. Prior to surgery, mean hip flexion was 93.1° (40°–130°). The mean follow-up period was 5.2 years (3–10 years).

Results

Bone union took an average of 7.7 months (3–24 months). Mean leg lengthening was 40.5 mm (15–70 mm) and was greater in patients without hip flexion contracture. None of the patients experienced any nerve injuries associated with leg lengthening, and radiographic evidence of loosening was not observed at the final follow-up.

Conclusions

SSO combined with cemented THA is an effective treatment for severely dislocated hips. Leg lengthening is not necessarily associated with nerve injuries, and the likelihood of this surgical complication may be related to the presence of hip flexion contracture.     

Total Hip Arthroplasties for Hartofilakidis Type C1 and C2 High Hip Dislocations Demonstrate Similar Survivorship and Clinical Function at Minimum 10-year Follow-up With Cementless Implants

BackgroundThis study aimed to determine the differences in survivorship, clinical function, and complications among patients who have Hartofilakidis Type C1 or C2 developmental dysplasia of the hips and underwent total hip arthroplasty (THA) with cementless implants.MethodsThis retrospective study identified 84 Hartofilakidis Type C hips that underwent THA between 2002 and 2011 with a minimum 10-year follow-up (mean, 13 years, range, 10 to 19 years). Survivorship, latest Harris Hip Scores and satisfaction levels, radiographic outcomes (eg, implant stability, rate and length of subtrochanteric shortening transverse osteotomy, leg-length discrepancy, cup position, and orientation), as well as complications (eg, dislocation, periprosthetic fracture, periprosthetic joint infection) were compared to analyze the differences between Hartofilakidis C1 and C2 hips.ResultsBetween C1 and C2 hips, no difference existed in the 15-year cumulative Kaplan-Meier survivorship, with the endpoint defined as any reoperation (93.1 versus 90.8%), aseptic loosening combined with periprosthetic joint infection (93.1 versus 96.2%), or aseptic loosening (94.8 versus 96.2%), latest Harris Hip Score (87.1 versus 86.1%), vertical (6.1 versus 6.0 mm) and horizontal (11.5 versus 10.3 mm) distance to the anatomic center of rotation, postoperative leg length discrepancy (11.2 versus 15.5 mm), dislocation (5.2 versus 11.5%), stem aseptic loosening (6.9 versus 7.7%), periprosthetic fracture (3.4 versus 7.7%), and intraoperative femoral fracture (32.8 versus 23.1%). However, Type C2 hips demonstrated more severe preoperative leg length discrepancy (66.9 versus 42.5 mm) and required a higher percentage of subtrochanteric shortening transverse osteotomies (84.6 versus 36.2%) that were longer (33.7 versus 26.47 mm) than the Type C1 hips.ConclusionWith cementless cups positioned near the anatomic acetabular center and cementless stems combined with subtrochanteric shortening transverse osteotomies, THAs for the Hartofilakidis Type C1 and C2 hips demonstrated similar survivorship, clinical function, and complications.     

Cementless Total Hip Arthroplasty for Patients with Crowe Type III or IV Developmental Dysplasia of the Hip: Two-Stage Total Hip Arthroplasty Following Skeletal Traction after Soft Tissue Release for Irreducible Hips

Background

Total hip arthroplasty (THA) for severe developmental dysplasia of the hip (DDH) is a technically demanding procedure for arthroplasty surgeons, and it is often difficult to reduce the hip joint without soft tissue release due to severe flexion contracture. We performed two-stage THAs in irreducible hips with expected lengthening of the affected limb after THA of over 2.5 cm or with flexion contractures of greater than 30 degrees in order to place the acetabular cup in the true acetabulum and to prevent neurologic deficits associated with acute elongation of the limb. The purpose of this study is to evaluate the outcomes of cementless THA in patients with severe DDH with a special focus on the results of two-stage THA.

Methods

Retrospective clinical and radiological evaluations were done on 17 patients with Crowe type III or IV developmental DDH treated by THA. There were 14 women and 3 men with a mean age of 52.3 years. Follow-ups averaged 52 months. Six cases were treated with two-stage THA followed by surgical hip liberalization and skeletal traction for 2 weeks.

Results

The mean Harris hip score improved from 40.9 to 89.1, and mean leg length discrepancy (LLD) in 13 unilateral cases was reduced from 2.95 to 0.8 cm. In the patients who underwent two-stage surgery, no nerve palsy was observed, and the single one-stage patient with incomplete peroneal nerve palsy recovered fully 4 weeks postoperatively.

Conclusions

The short-term clinical and radiographic outcomes of primary cementless THA for patients with Crowe type III or IV DDH were encouraging. Two-stage THA followed by skeletal traction after soft tissue release could provide alternative solutions to the minimization of limb shortenings or LLD without neurologic deficits in highly selected patients.     

Digital templating in primary total hip and knee arthroplasty

The use of digital radiography is becoming more prevalent in orthopedics. This transition impacts the ability to preoperatively plan for implants in total hip arthroplasty (THA) and total knee arthroplasty (TKA). This article reports on the clinical success of digital templating using the Advanced Case Plan (Stryker Imaging, Flower Mound, Texas) system in primary THA and TKA. Digital radiographs of 269 consecutive patients undergoing primary THA (93 cases) or TKA (176 cases) were templated using the Advanced Case Plan digital software package. A 25.4-mm metallic sphere was used as a calibrating marker. Anteroposterior hip and lateral knee radiographs were digitally templated preoperatively and compared to the actual size of the implants at the time of surgery. The accuracy of calibrating images using the metallic sphere was validated by measuring the diameter of femoral heads on 25 postoperative hip radiographs. Digital templating was accurate in predicting the correct implant size in 58.5% of THAs and 66% of TKAs. In 93% of THAs and 98.5% of TKAs, preoperative templating was within 1 size of the final implant. There were no cases in which the predicted implant size varied from the final components by >2 sizes. Calibrating the image using the metallic sphere marker was found to be highly accurate, predicting the correct femoral head size within 1.5 mm in all 25 cases (7 hemiarthroplasties and 18 THAs). Digital templating is an effective means for predicting the size of THA and TKA components, thus remaining a viable option as we transition into the modern era of digital radiography. Future studies will evaluate interobserver reliability and the impact of level of training on templating accuracy.     

Effectiveness of an accelerometer-based portable navigation for intraoperative adjustment of leg length discrepancy in total hip arthroplasty in the supine position

BackgroundThis study aimed to examine the accuracy of the HipAlign® accelerometer-based portable navigation system by measuring the intraoperative leg length change of patients who underwent total hip arthroplasty (THA) and comparing the measured leg length discrepancy (LLD) determined by the navigation system and a freehand technique.MethodsA total of 61 patients who underwent THA using the anterolateral approach in the supine position were included in this study and divided into two groups: those who underwent THA with navigation (Group N; N = 31) and with the freehand technique (Group F; N = 30). Statistical analyses were performed to compare the intraoperative leg length change, pre- and post-LLD, absolute values of post-LLD, and the number of patients with the postoperative LLD within 10 mm and 5 mm between the two groups. Additionally, we examined the correlation between the leg length change obtained through intraoperative navigation and measured from the radiographs. Moreover, to evaluate the navigation accuracy, we examined the correlation between the absolute error of leg length change and cup orientation.ResultsThe postoperative LLD was significantly lower and the number of patients with the postoperative LLD within 5 mm was significantly higher in Group N, compared with Group F. Additionally, the amount of leg length change measured intraoperatively by the navigation system was strongly correlated with the values obtained by the postoperative radiographic measurement with a small absolute error and minimal wasted time. Moreover, a significant positive correlation was found between the absolute error of the leg length change and that of the cup inclination.ConclusionsOur study demonstrates that the accelerometer-based portable navigation system is useful for the intraoperative adjustment of leg length discrepancy during THA for patients in the supine position, as it provides good accuracy and minimizes required time for use.     

Modular Necks in Primary Hip Arthroplasty Without Anatomical Deformity: No Clear Benefit on Restoration of Hip Geometry and Dislocation Rate. An Exploratory Study

Modular necks were introduced in total hip arthroplasty (THA) to improve restoration of hip-geometry and reduce dislocation-rates. This presumed advantage was evaluated retrospectively for patients with arthritis in otherwise anatomically normal hips. Restoration of hip-geometry was assessed on preoperative and postoperative calibrated radiographs in 95 consecutive primary THAs with a modular neck design and compared with 95 match controlled THAs with a similar monoblock stem. No significant differences were seen in restoration of body moment arm, leg length and cupangle. Offset restoration revealed a borderline significant difference (P = 0.48) with higher values for the monoblock stem. In both groups 4 dislocations within one year were encountered. In this study modular necks did not reveal a clear benefit in restoring hip geometry and dislocation rate after straightforward THA.     

Preoperative planning for revision total hip arthroplasty

Similar to total hip arthroplasty (THA), preoperative planning is more important for revision THA and includes a thorough clinical evaluation (ie, patient history, physical examination, and laboratory tests, including aspiration and culture) as well as radiographic assessment (ie, for changes in bone loss and quality, for leg length, and for templating to choose the correct components). Similar to primary THA, preoperative planning for revision THA must include the inherent possibility of failure. Careful planning of the current technology and expertise to perform THA will help minimize potential problems. The essence of preoperative planning in revision THA can be summed up simply: Be prepared.     

全髋关节置换术治疗成人Crowe Ⅳ型先天性髋关节脱位的临床研究

目的探讨CroweⅣ型先天性髋关节脱位患者全髋关节置换术的手术方法及预防神经损伤的对策。方法35例（39髋）CroweⅣ型先天性髋关节脱位患者行全髋关节置换术,均为女性,年龄36～56岁,平均46岁。获得随访31例35髋,随访时间1年～8年,平均4年。手术采用后外侧切口。髋臼侧除1例2髋外,均在真臼水平安放臼杯并使用非骨水泥型假体,股骨侧5例5髋选用骨水泥型假体,其余均选用非骨水泥型假体。2例2髋以往曾行转子下截骨者先行转子下截骨矫正术,再植入非骨水泥型假体。采用髋关节功能评分（Harris评分）评定髋关节功能,术前平均43分。结果获得随访的31例（35髋）中,5例5髋发生术中骨折,其中小转子轻微襞裂骨折3例3髋,大转子不全骨折2例2髋,但股骨假体稳定,予钢丝固定或未作特殊处理。3髋发生异位骨化,均为BrookⅡ型。2例术后分别出现坐骨神经或股神经刺激症状,1个月后恢复正常。随访期间内无一例发生术后感染、术中术后髋关节脱位、假体松动及有明显临床表现的深静脉血栓形成等并发症。术后随访时Harris评分平均87分,术后肢体延长4～6cm,平均5cm,肢体短缩得到满意纠正。结论后外侧人路、真臼水平重建髋臼是CroweⅣ型先天性髋关节脱位全髋关节置换术安全、有效的手术方法。     

Total Hip Arthroplasty With Subtrochanteric Shortening Osteotomy in Patients With High Hip Dislocation Secondary to Childhood Septic Arthritis: A Matched Comparative Study With Crowe IV Developmental Dysplasia

BackgroundTotal hip arthroplasty (THA) with subtrochanteric shortening osteotomy (SSO) is performed to manage hips with high dislocations. We compared outcomes of THA with SSO in patients with high hip dislocation resulting from childhood septic arthritis and Crowe IV developmental dysplasia of the hip (DDH).MethodsWe reviewed 60 THAs with SSO performed between May 1996 and December 2013. Thirty-one cases were classified as sequelae of childhood infection and 29 as DDH. Twenty-five hips were selected for each group after the propensity score was matched with preoperative demographics and leg length discrepancy (LLD). Clinical scores, complication and reoperation rates, radiographic results, and survivorships were compared. The mean duration of follow-up was 12.3 (range 5-22) years.ResultsThe average correction in LLD was 2.5 cm for childhood infection and 3.6 cm for DDH (P = .002). The infection group received more transfusions (mean 3.3 vs 2.0 units, P = .002), required more time for union of osteotomy site (mean 6.8 vs 5.2 months, P = .042), and reported lower Harris Hip Score (mean 85.1 vs 91.3, P = .017). Reoperations were performed in 11 (44%) previously infected hips and 3 (12%) DDHs (P = .012). Kaplan-Meier survivorship with an endpoint of revision for any reason was lower in the infection group (83.6%) than in the DDH group (100%) at 10 years (log rank, P = .040).ConclusionTHA with SSO in high hip dislocation secondary to childhood septic arthritis demonstrated less favorable clinical outcomes with increased risks of complication, compared with those performed in Crowe IV DDH with similar degree of chronic dislocation.     

Leg length equalization during total hip replacement

A method of equalization of leg lengths during total hip replacement surgery was developed which utilizes the concept of equalizing the vertical dimensions of the resected femoral head and neck segment and the remaining hip joint cartilage space, which are removed during the procedure, with the vertical dimensions of the femoral and acetabular prostheses, which are implanted into that void. This was accomplished by determining the dimensions of the prostheses from careful preoperative templating technique and by using a simple arithmetic formula to determine the level of the femoral neck osteotomy. The level of the osteotomy was made by a measurement from the top of the dislocated head of the femur to the medial femoral neck calcar. The radiologic postoperative leg length differences of a consecutive series of 84 patients undergoing primary total hip replacement using this method were determined. The average discrepancy was 2.8 mm. Seventy-five patients (89%) were found to have a postoperative leg length discrepancy of 6 mm (1/4 inch) or less. Six patients (7%) had a discrepancy of 7 to 13 mm, and only three patients (4%) had more than 13 mm (1/2 inch) leg length difference. Using this technique only two patients (2.5%) with unilateral hip replacements had leg lengthening of more than 6 mm.     

Gait Analysis of Leg Length Discrepancy—Differentiated Hip Replacement Patients With Developmental Dysplasia: A Midterm Follow-Up

Background

Few studies investigate gait characteristics and symmetry of developmental dysplasia of the hip patients (Crowe II and III) after total hip arthroplasty (THA) whose leg length discrepancy (LLD) is within 20 mm. Our study aimed to explore whether gait analysis parameters in these patients can return to the level of unaffected people and how bodies compensate for the discrepancy.

Accurate Leg Length Measurement in Total Hip Arthroplasty: A Comparison of Computer Navigation and a Simple Manual Measurement Device

Background

Several studies have shown that better placement of the acetabular cup and femoral stem can be achieved in total hip arthroplasty (THA) by using the computer navigation system rather than the free-hand alignment methods. However, there have been no comparisons of the relevant clinical advantages in using the computer navigation as opposed to the manual intraoperative measurement devices. The purpose of this study is to determine whether the use of computer navigation can improve postoperative leg length discrepancy (LLD) compared to the use of the measurement device.

Methods

We performed a retrospective study comparing 30 computer-assisted THAs with 40 THAs performed using a simple manual measurement device.

Results

The postoperative LLD was 3.0 mm (range, 0 to 8 mm) in the computer-assisted group and 2.9 mm (range, 0 to 10 mm) in the device group. Statistically significant difference was not seen between the two groups.

Conclusions

The results showed good equalization of the leg lengths using both computed tomography-based navigation and the simple manual measurement device.     

人工全髋关节置换术术前的模板测量与术后评估

目的通过全髋关节置换术术前模板测量与术后相关因素的评估,探讨全髋关节置换术术前模板测量的准确性和重要性.方法 2003年10月至2004年9月,选取因特发性股骨头无菌性坏死行单侧全髋关节置换术的19 例病人作为研究对象,其中男11 例,女8 例.年龄40～74 岁,平均58.7 岁.术前通过临床查体及骨盆X光正位片,对双下肢不等长和双侧股骨偏心距的差异程度进行测量和评估.再利用模板测量,预测髋臼及股骨假体的型号及置入位置,估计股骨颈的截骨水平以及预定出平衡双下肢长度的计划.术后对这些指标进行评估和验证.结果 19 例患者中术前有15 例存在双下肢不等长,术后这些患者的下肢不等长情况都有显著改善.此19 例患者双下肢长度差均值由术前8.4 mm减小到4.4 mm,73.7%的患者术后双下肢长度差异在5 mm之内.双侧股骨偏心距差均值由术前6.3 mm减小到3.0 mm.术前模板测量出的假体型号与实际应用的假体比较,髋臼假体符合率为52.6%,股骨柄假体符合率为63.2%.结论人工全髋关节置换术术前精确的模板测量对于重建髋关节结构和功能及恢复下肢长度具有重要的意义.     

The utility of digital templating in Total Hip Arthroplasty with Crowe type II and III dysplastic hips

With the superiority of digital imaging, conventional preoperative acetate templating is gradually being replaced by digital templating in total hip arthroplasty (THA). The purpose of this study was to assess the utility of digital templating for patients with Crowe type II and III dysplastic hips. In this study, 41 THA patients with Crowe type II or III dysplastic hips and 48 THA patients with other primary diseases were retrospectively reviewed. All patients were fitted with cementless prostheses in 2008. For the THA patients with dysplastic hips, we attempted to restore their hip centres to the position of the true acetabulum. Digital templating was the method chosen to achieve hip centre restoration. The prosthesis prediction accuracy (within ± one size using digital templating) was 20 (48.8%) for the cup size and 30 (73.2%) for the stem size. Meanwhile, for patients with other primary diseases, the accuracy for the cup size within ± one size was 34 (70.8%) and for the stem size accuracy was within ± one size in 38 (79.2%). Between the two patient groups, there was a significant difference in the predicted cup size. In patients with dysplastic hips, the low accuracy of the predicted cup size may have resulted from difficulty in predicting the vertical location of the hip centre. Despite this limitation, preoperative planning using digital templating is a convenient technique for THA patients with Crowe type II and III dysplastic hips.