Cementless Total Hip Arthroplasty With a High Hip Center for Hartofilakidis Type B Developmental Dysplasia of the Hip: Results of Midterm Follow-Up

Comparative Study of Highly Cross-Linked Polyethylene Liner Wear by Hip Center Location Using Elevated Hip Center Technique in Crowe I to III Hip Dysplasia: Outcomes for a Minimum of Eighteen Years of Follow-Up

BACKGROUND

The literature has reported that supero-lateralization of the femoral head increases the rates of aseptic loosening and prosthesis revision. However, there are few reports on the influence of different hip center positions on liner wear with more than a 15-year follow-up period.

METHODS

From April 2000 to August 2003, 91 patients underwent 108 total hip arthroplasties using a highly cross-linked polyethylene liner combined with zirconia femoral head and cup components. Pelvic radiographs were used to assess the vertical and horizontal distances to the center of the hip and the amount of liner wear. Mean patient age at the time of surgery was 54 years (range, 33 to 73), and mean follow-up duration was 19 years (range, 18 to 21).

RESULTS

Average liner wear was 0.221 mm, with average annual wear of 0.012 mm/year. Mean vertical and horizontal distances for the hip center were 24.9 and 31.8 mm, respectively. There was no difference in linear wear between patients who had different hip center heights (<20, 20 to 30, and >30 mm), and quadrant partitioning showed no differences across the 4 quadrant zones.

CONCLUSION

At a minimum of 18 years of follow-up in patients having developmental dysplasia of the hip who had different Crowe subtypes and different hip centers, elevated hip center and uncemented fixation techniques using a highly cross-linked polyethylene on ceramic components were associated with very low wear rates and excellent functional scores.

Effect of Hip Joint Center on Multi-body Dynamics and Contact Mechanics of Hip Arthroplasty for Crowe IV Dysplasia

OBJECTIVE

To investigate the hip joint forces, Von Mises stress, contact pressure and micro-motion of hip prosthesis for developmental dysplasia of the hip (DDH) patients under different hip joint centers using musculoskeletal (MSK) multi-body dynamics and finite element analysis.

METHODS

Both MSK multi-body dynamics model and finite element (FE) model were based on CT data of a young female DDH patient with total hip replacement and were developed to study the biomechanics of the S-ROM hip prosthesis. The same offset of hip joint center along all six orientations compared with the standard position was set to predict its effects on both MSK multi-body dynamics and contact mechanics during one gait cycle.

RESULTS

The hip joint forces in the entire walking gait cycle showed two peak values and clear differences between them under different hip joint centers. The hip joint force increased when the hip joint center moved posteriorly (2101 N) and laterally (1969 N) to the anatomical center (1848 N) at the first peak by 13.7% and 6.6%, respectively. The hip joint force increased sharply when the hip center deviated laterally (2115 N) and anteriorly (2407 N), respectively, from the standard position (1742 N) at the second peak. For the sleeve of the S-ROM prosthesis, the maximum Von Mises stress and contact pressure of the sleeve increased if the hip joint center deviated from the anatomical center posteriorly at the first peak. However, the Von Mises stresses and contact pressure increased at anterior and lateral orientations, compared to that of the standard position at the second peak. Small changes were observed for the maximum relative sliding distance along most of the orientations at both peaks except in the lateral and medial orientations, in which an increase of 8.6% and a decrease of 13.6% were observed, respectively.

CONCLUSION

The hip joint center obviously influenced the hip joint forces, stress, contact pressure and micro-motion of the hip implant for this female patient.

Restoring Rotation Center in Total Hip Arthroplasty for Developmental Dysplasia of the Hip with the Assistance of Three Dimensional Printing Technology: A Pilot Study

Objective

To develop a new method to restore hip rotation center exactly and rapidly in total hip arthroplasty (THA) with the assistance of three dimensional (3D) printing technology and evaluate its clinical and radiological outcomes.

Methods

From March 2014 to July 2018, a total of 17 patients (five hips of four men and 16 hips of 13 women) with end‐stage osteoarthritis secondary to developmental dysplasia of the hip who underwent THA were analyzed and followed up retrospectively. The average age is 58.00 ± 8.12 years (range from 45 to 71 years). Simulated operations were performed on 3D printed hip models for preoperative planning. The morphology of Harris fossa and acetabular notches were recognized and restored to locate the acetabular center. The size of bone defect was measured by the bone wax method. The agreement on the size of acetabular cup and bone defect between simulated operations and actual operations were analyzed. Harris Hip Score (HHS) was used to evaluate the recovery of hip joint function. The vertical distance and horizontal distance of the rotation center on the pelvis plain radiograph were measured, which were used to assess the efficacy of restoring hip rotation center and acetabular cup migration.

Results

The mean sizes of bone defect in simulated operations and THA were 4.58 ± 2.47 cm² and 4.55 ± 2.57 cm² respectively. There was no significant difference statistically between the sizes of bone defect in simulated operations and the actual sizes of bone defect in THA (t = 0.03, P = 0.97). The sizes of the acetabular cup of simulated operations on 3D print models showed a high rate of coincidence with the actual sizes in the operations (ICC = 0.93). All 17 patients were available for clinical and radiological follow‐up. The average follow‐up time was 18.35 ± 6.86 months (range, 12–36 months. The average HHS of the patients was improved from (38.33 ± 6.07) preoperatively to the last follow‐up (88.61 ± 3.44) postoperatively. The mean vertical and horizontal distances of hip rotation center on the pelvic radiographs were restored to 15.12 ± 1.25 mm and 32.49 ± 2.83 mm respectively. No case presented dislocation or radiological signs of loosening until last follow‐up.

Conclusions

The application of 3D printing technology facilitates orthopedists to recognize the morphology of Harris fossa and acetabular notches, locate the acetabular center and restore the hip rotation center rapidly and accurately.

Jumbo cup in hip joint renovation may cause the center of rotation to increase

BACKGROUND

Utilizing the large jumbo cup in revision total hip arthroplasty is an effective approach to cure many lacunar and segmental peripheral bone defects. However, with the use of the jumbo cup, the center of the hip joint may become elevated relative to the primary acetabulum, and the diameter of the large cup is greater.

AIM

To study the height and the significance of the elevation of the hip joint center.

METHODS

Eighty-eight patients matched the criteria for this condition and were included in the study. The center height of the hip joint was measured relative to the opposite normal hip joint. The diameter of the jumbo cup was measured and checked according to operation notes, and the diameter of the jumbo cup was measured with a prosthesis label. Then, the horizontal and vertical centers of rotation were measured on the surgical side and opposite side. The average center height of the hip joint on the renovated side and the opposite side and the position of the hip cup relative to the teardrop were compared using a paired t-test.

RESULTS

Radiometric analysis showed that the average hip joint center was elevated by 7.6 mm. The rotational center height delta of the renovated hip was 7.6 ± 5.6 mm, and there was an obvious difference between the two groups (P = 0.00). The difference in horizontal distance was 0.5 ± 5.1 mm (-11.5 -14.0 mm), and there was no obvious difference between the two groups (P = 0.38). According to the foreign standard, the rotational center height delta of the renovated hip was 7.5 ± 6.2 mm, and there was a significant difference between the two groups (P = 0.00). There was no obvious difference between the domestic and foreign standards (P > 0.05) between the two groups.

CONCLUSION

The application of the jumbo cup elevates the rotational center of the hip joint, but it is feasible and effective to use the jumbo cup.

Does Cup Position at the High Hip Center or Anatomic Hip Center in THA for Developmental Dysplasia of the Hip Result in Better Harris Hip Scores and Revision Incidence? A Systematic Review

BACKGROUND

One goal of THA is to restore the anatomic hip center, which can be achieved in hips with developmental dysplasia by placing cups at the level of the native acetabulum. However, this might require adjuvant procedures such as femoral shortening osteotomy. Another option is to place the cup at the high hip center, potentially reducing surgical complexity. Currently, no clear consensus exists regarding which of these cup positions might offer better functional outcomes or long-term survival.

QUESTION/PURPOSE

We performed a systematic review to determine whether (1) functional outcomes as measured by the Harris hip score, (2) revision incidence, and (3) complications that do not result in revision differ based on the position of the acetabular cup (high hip center versus anatomic hip center) in patients undergoing THA for developmental dysplasia of the hip (DDH).

METHODS

We performed a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, including studies comparing the functional outcomes, revision incidence, and complications of primary THA in dysplastic hips with acetabular cups placed at the high hip center versus those placed at the anatomic hip center, over any time frame. The review protocol was registered with PROSPERO (registration number CRD42020168183) before commencement. Of 238 records, eight comparative, retrospective nonrandomized studies of interventions were eligible for our systematic review, reporting on 207 hips with cups placed at the high hip center and 268 hips with cups at the anatomic hip center. Risk of bias within eligible studies was assessed using the Risk Of Bias In Non-randomized Studies of Interventions tool. Due to low comparability between studies, data could not be pooled, so these studies were assessed without summary effects.

RESULTS

Six studies compared Harris hip scores, two of which favored high hip center cup placement and three of which favored anatomic hip center cup placement, although none of the differences between cohorts met the minimum clinically important difference. Five studies reliably compared revision incidence, which ranged from 2% to 9% for high hip center at 7 to 15 years and 0% to 5.9% for anatomic hip center at 6 to 16 years. Five studies reported intra- and postoperative complications, with the high hip center being associated with higher incidence of dislocation and lower incidence of neurological complications. No clear difference was observed in intraoperative complications between the high hip center and anatomic hip center.

CONCLUSION

No obvious differences could be observed in Harris hip score or revision incidence after THA for osteoarthritis secondary to DDH between cups placed at the anatomic hip center and those placed at the high hip center. Placement of the acetabular cup in the high hip center may lead to higher risk of dislocation but lower risk of neurologic complications, although no difference in intraoperative complications was observed. Surgeons should be able to achieve satisfactory functional scores and revision incidence using either technique, although they should be aware of how their choice influences hip biomechanics and the need for adjunct procedures and associated risks and operative time. These recommendations should be considered with respect to the several limitations in the studies reviewed, including the presence of serious confounding factors and selection biases, inconsistent definitions of the high hip center, variations in dysplasia severity, small sample sizes, and follow-up periods. These weaknesses should be addressed in well-designed future studies.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Total Hip Replacement in Developmental Hip Dysplasia: A Narrative Review

The reconstruction of the hip joint in patients suffering from developmental hip dysplasia (DDH) is a demanding procedure and presents many challenges to the reconstructive surgeon. Higher rates of mechanical complications are present in this group of patients. The results of cemented and uncemented implants used in DDH patients are very promising, according to recent outcomes. However, the surgeon has to be aware of several complications, in order to establish an uneventful surgical management of DDH. The specific article investigates the technical challenges and clinical results of total hip arthroplasty in patients with DDH.

Radiographic factors to predict operation time of direct anterior total hip arthroplasty for dysplastic hips

BACKGROUND

This study aimed to identify radiographic factors that could predict surgical difficulty in direct anterior total hip arthroplasty (THA) for dysplastic hips.

PATIENTS AND METHODS

The clinical records of 160 patients (204 hips) who underwent primary THA for the treatment of developmental dysplasia of the hip were retrospectively investigated. All THAs were performed through a direct anterior approach by a single surgeon. A multiple regression analysis was developed to identify the independent predictor of operation time, including variables such as age, sex, height, body mass index (BMI), the use of bone cement, previous hip surgery, and radiographic references, including the pelvic horizontal to vertical ratio, the extent of proximal and horizontal migration of the femoral head, flatness of the femoral head, and the vertical distance between the tips of the greater trochanter and the femoral head.

RESULTS

A multiple regression analysis revealed that as radiographic factors, proximal migration of the femoral head, and lower position of the femoral head related to the greater trochanter were significantly associated with longer operation time. In addition, our results revealed that younger age, male sex, height, high BMI, cement use, and previous hip surgery were also significantly associated with longer operation time.

CONCLUSIONS

Our findings indicate that proximal migration of the femoral head and high-riding greater trochanter are isolated radiographic predictors of the longer operation time of direct anterior THA for dysplastic hips.

Subtrochanteric femoral shortening for hip centre restoration in complex total hip arthroplasty with functional outcome

Aims

Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips.

Methods

In all, 27 THAs in 25 patients requiring THA with femoral shortening between 2012 and 2019 were assessed. Bilateral shortening was required in two patients. Subtrochanteric shortening was required in 14 out of 27 hips (51.9%) with aetiology other than DDH or septic arthritis. Vertical centre of rotation (VCOR), horizontal centre of rotation, offset, and functional outcome was calculated. The mean followup was 24.4 months (5 to 92 months).

Results

The mean VCOR was 17.43 mm (9.5 to 27 mm) and horizontal centre of rotation (HCOR) was 24.79 mm (17.2 to 37.6 mm). Dislocation at three months following acetabulum reconstruction required femoral shortening for offset correction and hip centre restoration in one hip. Mean horizontal offset was 39.72 (32.7 to 48.2 mm) compared to 42.89 (26.7 to 50.6 mm) on the normal side. Mean Harris Hip Score (HHS) of 22.64 (14 to 35) improved to 79.43 (68 to 92). Mean pre-operative shortening was 3.95 cm (2 to 8 cm). Residual limb length discrepancy was 1.5 cm (0 to 2 cm). Sciatic neuropraxia in two patients recovered by six months, and femoral neuropraxia in one hip recovered by 12 months. Mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 13.92 (9 to 19). Mean 12-item short form survey (SF-12) physical scores of 50.6 and mental of 60.12 were obtained.

Conclusion

THA with subtrochanteric shortening is valuable in complex hips with high dislocation. The restoration of the hip centre of rotation and offset is important in these hips.

Level of evidence IV

Controlled fracture of the medial wall versus structural autograft with bulk femoral head to increase cup coverage by host bone for total hip arthroplasty in osteoarthritis secondary to developmental dysplasia of the hip: a retrospective cohort study

Background

Many methods have been proposed to increase cup coverage by host bone during primary total hip arthroplasty (THA) in hip osteoarthritis secondary to developmental dysplasia of the hip (DDH). However, there was no study comparing the results of controlled fracture of the medial wall with a structural autograft with a bulk femoral head.

Methods

Sixty-seven hips classified as Crowe II/III were retrospectively included in this cohort study, which consisted of 33 controlled fractures (group A) and 34 structural autografts (group B). The Harris Hip Scores (HHS) were recorded. The radiological assessments were analyzed. Also, complications are assessed. The paired-sample t test was used for data analysis before and after the operation, while the independent sample T test was used for the comparison between the two groups. The Pearson chi-square test or the Fisher exact test was used to analyze the qualitative comparative parameters. Kaplan-Meier was utilized in the analysis of survivorship with the end points as a revision for any component.

Results

All patients were reconstructed acetabulum at the anatomical location. HHS increased greatly for both groups (p = 0.18). No statistic difference was observed for the two groups in postoperative leg-length discrepancy (0.51 ± 0.29 cm for group A and 0.46 ± 0.39 cm for group B, p = 0.64 ), postoperative height of the hip center (2.25 ± 0.42 cm for group A and 2.09 ± 0.31 cm for group B, p = 0.13), and inclination of the cup (39 ± 4° for group A and 38 ± 3° for group B, p = 0.65 ). The rate of cup coverage for group B (94 ± 2%) was better than for group A (91 ± 5%), (p = .009). The rate of cup protrusio was 48 ± 4% for group A. For both groups, no statistical difference was observed in the cup diameter (p > .05), while group A showed less operation time than group B (p < .001). No complications were observed at the latest follow-up.

Conclusion

Controlled fracture of the medial wall to increase cup coverage by host bone at the anatomical location can act as an alternative technique for DDH Crowe II/III with the advantage of shorter operation time and less technically demanding.

Novel 3D printed integral customized acetabular prosthesis for anatomical rotation center restoration in hip arthroplasty for developmental dysplasia of the hip crowe type III: A Case Report

RATIONALE

Exact restoration of the rotation center in total hip arthroplasty (THA) is technically challenging in patients with end-stage osteoarthritis due to developmental dysplasia of the hip (DDH), especially in the Crowe type II and III procedures. The technical difficulty is attributable to the complex acetabular changes. In this study, a novel 3-dimensional (3D) printed integral customized acetabular prosthesis for anatomical rotation restoration in THA for DDH Crowe type III was developed using patient-specific Computer-aided design and additive manufacturing (AM) methods.

PATIENT CONCERNS

A 69-year-old female patient had developed left hip joint pain and restricted movement for 40 years; the symptoms had increased in the past 5 months. Pain, limited motion of the left hip joint, and lower limb length discrepancy were noted during physical examination.

DIAGNOSIS

The patient was diagnosed with left hip end-stage osteoarthritis secondary to DDH (Crowe type III).

INTERVENTION

A 3D printed acetabulum model was manufactured and a simulated operation was performed to improve the accuracy of reconstruction of the rotation center and bone defect. A 3D printed titanium alloy integral customized acetabular prosthesis was designed according to the result of simulated operation. The integral customized prothesis was implanted subsequently via the posterolateral approach. Radiography of the pelvis and Harris score assessment were performed during the perioperative period as well as at the 6- and 12-month follow-up.

OUTCOMES

The 3D printed integral customized acetabular prosthesis matched precisely with the reamed acetabulum. The rotation center was restored and the bone defect was exactly reconstructed. There were no signs of prosthetic loosening at the 12-month follow-up. The Harris score gradually improved during the follow-up period.

LESSONS

Satisfactory results of hip rotation restoration and bone defect reconstruction could be achieved by using 3D printed integral customized acetabular prosthesis, which provides a promising way to reconstruct the acetabulum in patients with DDH anatomically and rapidly for THA.

High Hip Center Technique in Total Hip Arthroplasty for Crowe Type II-III Developmental Dysplasia: Results of Midterm Follow-up

Objectives

We aimed to show the utility of high hip center technique used in patients with Crowe II–III developmental dysplasia of the hip at the midterm follow‐up and evaluated the clinical and radiographic results between different heights of hip center.

Methods

From December 2003 to November 2013, we retrospectively evaluated 69 patients (85 hips) with Crowe II–III dysplasia who underwent a high hip center cementless total hip arthroplasty. The patients were divided into two groups according to the height of hip center, respectively group A (≥ 22 mm and < 28 mm) and group B (≥28 mm). The survivorship outcomes and radiographic and clinical results, including the vertical and horizontal distances of hip center, femoral offset, abductor lever arm, cup inclination, leg length discrepancy, Trendelenburg sign, and limp were evaluated.

Results

The mean follow‐up time was 8.9 ± 1.8 years. The mean location of the hip center from the inter‐teardrop was 25.1 ± 1.6 mm vertically and 30.0 ± 3.8 mm horizontally in group A, and 33.1 ± 4.8 mm vertically and 31.4 ± 6.1 mm horizontally in group B. Eleven hips of group B showed a lateralization over 10 mm, and the same was shown in one hip in group A (P = 0.012). There were no statistically significant differences between two groups in postoperative femoral offset, abductor lever arm, leg length discrepancy and cup inclination. At the final follow up, the mean WOMAC and Harris hip score were significantly improved in both groups. Of the 85 hips, four hips in group A and three hips in group B showed a positive Trendelenburg sign. Additionally, four patients in group A and two patients in group B presented with a limp. No significant differences were shown regarding the Harris hip score, WOMAC score, Trendelenburg sign, and limp between two groups. One hip of group A was revised by reason of dislocation at 8.3 years after surgery. One hip of group B was diagnosed with osteolysis and underwent a revision at 8.1 years after surgery. The Kaplan–Meier implants survivorship rates at the final follow‐up for all‐causes revisions in group A and group B were similar (96.7% [95% confidence interval, 90.5%–100%] and 96.2% [95% confidence interval, 89.0%–100%], respectively).

Conclusions

The high hip center technique is a valuable alternative to achieve excellent midterm results for Crowe II–III developmental dysplasia of the hip. Further, between the groups with differing degrees of HHC, there were no significant differences in outcomes or survivorship in our study.

A Comparative Study of Patients' Subjective Feelings Toward Total Hip Arthroplasty with Patient-Specific Instruments and Traditional Total Hip Arthroplasty

OBJECTIVE

To determine whether differences exist in patients' subjective feelings, daily life, and surgical satisfaction between those who underwent surgery for developmental dysplasia of the hip (DDH) using patient-specific instruments (PSIs) and those who underwent traditional surgical total hip arthroplasty (THA).

METHODS

We selected 30 adult patients with various types of DDH who underwent surgery during 2016-2017 at our hospital. The patients were divided into PSI surgery group and the traditional surgery group. All patients underwent follow-up, and we collected data on the Harris Hip Score, Oxford University Hip Score (OHS), Forgotten Joint Score (FJS-12), Visual Analogue Scale (VAS) score, patient satisfaction score, intraoperative surgical time, amount of bleeding and postoperative complications incidence for both groups. We then performed statistical analyses on the data.

RESULTS

The Harris Hip Score, OHS, VAS score, patient satisfaction score, and mean bleeding volume did not differ statistically significantly (t-tests, P > 0.05). No statistically significant differences were found between surgical groups in the incidence of complication and sub-trochanteric osteotomy, or in the surgical side (chi-square tests, P > 0.05). For the experimental group, the FJS-12 score was 80.0 ± 12.0, and for the control group the score was 68.5 ± 16.1. The operative time of the experimental group was 138.4 ± 32.2 min, while that of the control group was 88.9 ± 26.8 min. The values of these data differed significantly (t-tests, P < 0.05).

CONCLUSIONS

The novel PSI designed by our group has certain advantages for the short-term subjective feelings of patients after THA, but it may cause prolonged operative times.

Subtrochanteric femoral shortening for hip centre restoration in complex total hip arthroplasty with functional outcome

Aims

Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips.

Methods

In all, 27 THAs in 25 patients requiring THA with femoral shortening between 2012 and 2019 were assessed. Bilateral shortening was required in two patients. Subtrochanteric shortening was required in 14 out of 27 hips (51.9%) with aetiology other than DDH or septic arthritis. Vertical centre of rotation (VCOR), horizontal centre of rotation, offset, and functional outcome was calculated. The mean followup was 24.4 months (5 to 92 months).

Results

The mean VCOR was 17.43 mm (9.5 to 27 mm) and horizontal centre of rotation (HCOR) was 24.79 mm (17.2 to 37.6 mm). Dislocation at three months following acetabulum reconstruction required femoral shortening for offset correction and hip centre restoration in one hip. Mean horizontal offset was 39.72 (32.7 to 48.2 mm) compared to 42.89 (26.7 to 50.6 mm) on the normal side. Mean Harris Hip Score (HHS) of 22.64 (14 to 35) improved to 79.43 (68 to 92). Mean pre-operative shortening was 3.95 cm (2 to 8 cm). Residual limb length discrepancy was 1.5 cm (0 to 2 cm). Sciatic neuropraxia in two patients recovered by six months, and femoral neuropraxia in one hip recovered by 12 months. Mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 13.92 (9 to 19). Mean 12-item short form survey (SF-12) physical scores of 50.6 and mental of 60.12 were obtained.

Conclusion

THA with subtrochanteric shortening is valuable in complex hips with high dislocation. The restoration of the hip centre of rotation and offset is important in these hips.

Level of evidence IV

Femoral shortening useful in conditions other than DDH and septic sequelae. Restoration of hip centre combined with offset to be planned and ensured.

Best bone of acetabulum for cup component placement in Crowe types I to III dysplastic hips: a computer simulation study

BACKGROUND

During cup implantation, vertical height of the cup center (V-HCC) should be precisely controlled to achieve sufficient bone-cup coverage (BCC). Our study aimed to investigate the acetabular bone stock and the quantitative relationship between V-HCC and BCC in Crowe types I to III hips.

METHODS

From November 2013 to March 2016, pelvic models of 51 patients (61 hips) with hip dysplasia were retrospectively reconstructed using a computer software. Acetabular height and doom thickness were measured on the mid-acetabular coronal cross section. V-HCC was defined as the vertical distance of cup rotational center to the interteardrop line (ITL). In the cup implantation simulation, the cup was placed at the initial preset position, with a V-HCC of 15 mm, and moved proximally by 3-mm increments. At each level, the BCC was automatically calculated by computer. Analysis of variance and Kruskal-Wallis test were used to compare the differences between groups.

RESULTS

There were no significant between-group differences in maximum thickness of the acetabular doom; however, peak bone stock values were obtained at heights of 41.63 ± 5.14 mm (Crowe type I), 47.58 ± 4.10 mm (Crowe type II), and 55.78 ± 3.64 mm (Crowe type III) above the ITL. At 15 mm of V-HCC, median BCC was 78% (75-83%) (Crowe type I), 74% (66-71%) (Crowe type II), and 61% (57-68%) (Crowe type III). To achieve 80% of the BCC, the median V-HCC was 16.27 (15.00-16.93) mm, 18.19 (15.01-21.53) mm, and 24.13 (21.02-28.70) mm for Crowe types I, II, and III hips, respectively.

CONCLUSION

During acetabular reconstruction, slightly superior placement with V-HCC <25 mm retained sufficient bone coverage in Crowe I to III hips.

Primary Total Hip Arthroplasty in Severe Dysplastic Hip Osteoarthritis With a Far Proximal Cup Position

BACKGROUND

Developmental hip dysplasia is the most common cause of secondary hip osteoarthritis. Due to severe acetabular bone deficiency, cup positioning in total hip arthroplasty (THA) of dysplastic hips remains a surgical challenge. The aim was to analyze the functional outcome of far proximal cup positions in primary THA.

METHODS

Fifty patients (61 hips) with THA for severe dysplastic osteoarthritis and a far proximal cup position were included. Patients were divided according to the heights of the implanted cups with increasing vertical distance from the interteardrop line (group A: 55-65 mm, group B: 65-75 mm, group C: >75 mm). Functional outcome was assessed at latest follow-up (38 ± 16 months) by Lower Extremity Functional Score, Tegner Activity Score, and Harris Hip Score (HHS). Patients answered a Patient Satisfaction Questionnaire. Leg length discrepancy was estimated radiographically.

RESULTS

The Lower Extremity Functional Score significantly decreased in C (45.3 ± 25) compared to A (66.7 ± 15.3) and B (67.9 ± 9.9). The Tegner Activity Score significantly increased in all subgroups from preoperative to postoperative (2.2 ± 1.3 to 4.1 ± 1.4; P < .05). The mean overall HHS was 89.3 ± 14.7 (A: 89.5 ± 14.3, B: 94.3 ± 6.5, C: 78.3 ± 22.1). The HHS domains of activity of daily life and gait were significantly reduced in C (P < .05). Patients described a high satisfaction level with the surgery. No significant differences were found with regard to preoperative and postoperative leg lengthening (P = .881). Neither dislocations, impingement problems nor neurologic complications were observed.

CONCLUSION

Primary THA without any concomitant surgical interventions with a far proximal cup position offers a safe and effective treatment option in severe dysplastic hip osteoarthritis.

Use of an offset head center acetabular shell in difficult primary total hip arthroplasties

Several conditions may predispose patients to development of antero-lateral acetabular bone deficiency, including developmental dysplasia of the hip, osteonecrosis, or septic arthritis, among others. This may compromise the ability to gain acetabular component stability and impair reliable fixation. Large acetabular shells have often been used to achieve adequate fixation in scenarios of severe bone loss, however, these techniques have been shown to elevate the center of rotation (COR) of the hip and alter hip biomechanics. Recently, a new acetabular shell was developed with a goal of maintaining the native hip COR while achieving good fixation with standard instrumentation and technique. Previous radiographic studies have demonstrated the efficacy of this shell in lowering hip COR. In this case series, we demonstrate the use of this shell in patients with difficult hip pathologies. We have demonstrated how this offset COR acetabular shell may help bring down the COR of the hip in these quite challenging cases utilizing conventional techniques.

Does hip center location affect the recovery of abductor moment after total hip arthroplasty?

BACKGROUND

In total hip arthroplasty (THA), placing the cup in an anatomic position is not always possible in case of deformities related to developmental dysplasia of the hip (DDH). Thus far, the influence of a hip center on the abductor moment after THA has not been clearly elucidated. Therefore, we performed a retrospective study to assess (1) how abductor muscle moment recovers postoperatively in THA and (2) whether acetabular cup position affects the recovery of abductor moment.

HYPOTHESIS

A high hip center affects the recovery of abductor moment of a dysplastic hip after THA.

PATIENTS AND METHODS

We evaluated 100 patients, who underwent unilateral primary THA, at 12 months postoperatively. The study included 86 women and 14 men, with a mean age of 65.5±9.9 years (range, 40 to 86 years). Patients with secondary osteoarthritis due to DDH were included (Crowe 1: 76; Crowe 2: 15, Crowe 3:9, and Crowe 4: none). A cementless straight stem was implanted in all hips. Hip abductor moment was measured using a belt-stabilized hand-held dynamometer. The ratio of moment of the affected side to that of the contralateral side was calculated as moment ratio. The horizontal and vertical centers of rotation (H-COR and V-COR) (with respect to the inter teardrop line) and vertical shift (V-shift) (difference in V-COR between the affected hip and the contralateral normal hip) were determined.

RESULTS

At 6 and 12 months postoperatively, the abductor moment ratios were 95.1 and 94.7%, respectively. Significant negative correlation was observed between the postoperative abductor moment ratio and V-COR at 6 months postoperatively (r=-0.2436, p=0.0238). Significant delay in the recovery of abductor moment ratio was observed in the groups with higher hip center (V-shift>15mm) (odds ratio=12.7; 95% CI: 2.11-232.1, p=0.0034) at 6 months postoperatively, which was fully recovered at 12 months postoperatively.

DISCUSSION

Superior placement of a hip center, more than 15mm above the true hip center, delayed the recovery of abductor muscle moment after THA.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Developmental Dysplasia Treated With Cementless Total Hip Arthroplasty Utilizing High Hip Center Reconstruction: A Minimum 13-Year Follow-up Study

BACKGROUND

The primary aim of this study was to determine the clinical outcomes at 13-year follow-up of patients diagnosed with developmental dysplasia of the hip and subsequently treated with total hip arthroplasty (THA). The secondary aim was to investigate the effect of hip center location on clinical outcomes and polyethylene wear.

METHODS

We reviewed data from a consecutive series of 104 patients (123 hips) from a single center. Patients were treated with THA with the high hip center (HHC) technique using cementless acetabular shells and highly cross-linked liners. Radiographs were collected preoperatively and through 13-year follow-up to assess degree of dysplasia (Crowe classification), component positioning, occurrence of bone resorption, and polyethylene wear. The Harris Hip Score (HHS) was administered at 4 and 13 years.

RESULTS

No patients were lost to follow-up, and one was revised for femoral loosening. Radiolucency was seen in 20% of patients and was not associated with HHC (P = .560). No patients developed osteolysis. The wear rate was low for all patients (mean: 3 ± 19 μm/y) and not associated with HHC (P = .852). The median 13-year HHS was 91.9 (interquartile range: 84.8-97.0). There was a statistically significant decline from the 4- to 13-year HHS (P < .001) for the Crowe II-IV group, although 82% of these patients remained above 80 points at 13 years. The nondysplastic and Crowe I group showed no longitudinal change in HHS (P = .243).

CONCLUSION

This cup design and highly cross-linked polyethylene liner combination demonstrates excellent clinical outcomes, similar to THA for primary osteoarthritis, through 13-year follow-up in patients with various degrees of developmental dysplasia of the hip and HHC reconstructions.

A simple technique to strengthen the initial and mid-term to long-term stability of the cup during total hip arthroplasty in developmental dysplasia of the hip

Objectives:

To assess the effects of a technique of cup blocking screws combined with impaction bone grafting during total hip arthroplasty (THA) for patients with developmental dysplasia of the hip (DDH).

Methods:

From August 2011 to July 2015, 53 patients (59 hips) with DDH in our hospital were treated with THA using the technique of cup blocking screws combined with impaction particulate bone grafting. These patients were prospectively followed, and the clinical and imaging results were collected.

Results:

Harris hip score (HHS) was raised from 41.24 before surgery to 91.49 at the latest follow-up (p<0.001). Length discrepancy (LLD) was reduced from 28.97 mm before surgery to 6.08 mm after surgery (p<0.001). No loosening of the cup was detected at the last follow-up. The differences were insignificant in cup inclination and rate of cup coverage among the 3 groups of Crowe type II, type III, and type IV DDH (p>0.05).

Conclusion:

The technique of cup blocking screws combined with impaction particulate bone grafting is simple and reliable, and it not only simplifies the attainment of initial stability, but also strengthens the mid-term to long-term stability during THA in DDH.

Computed Tomographic Evaluation of Bone Stock in Patients With Crowe Type III Developmental Dysplasia of the Hip: Implications for Guiding Acetabular Component Placement Using the High Hip Center Technique

BACKGROUND

We evaluated acetabular cup coverage (CC) and rim contact (RC) to evaluate the bone stock above the acetabulum for guiding acetabular component placement using the high hip center technique in patients with Crowe type III developmental dysplasia of the hip.

METHODS

Using hip computed tomography and image processing software, pelvises were reconstructed digitally in 20 hips with Crowe type III developmental dysplasia of the hip. Mimicked cup was placed with anteversion angles of 0° (group I), 5° (group II), and 10° (group III) respectively. In each group, the cup was placed at the anatomical hip center at first, and then the cup was moved up to 40 mm vertically about the native rotation center with an increment of 2.5 mm at each step. CC and RC were calculated and documented with each movement.

RESULTS

CC was 65.87%, 67.77%, and 68.98% for group I, group II, and group III at the native rotation center, and increased progressively to 86.45%, 85.85%, and 84.71% at 25 mm above. RC was 49.17%, 50.25%, and 51.92% for group I, group II, and group III at the native rotation center, and increased progressively to 86.87%, 86.39%, and 84.94% at 22.5 mm above. CC and RC were positively correlated, despite the different anteversion angles (r = 0.687 at 0°, 0.683 at 5°, and 0.645 at 10°; P < .001).

CONCLUSION

Computed tomography analysis and computer stimulation demonstrate that it is feasible to use high hip center technique in Crowe type III hips.

Radiographic Underestimation of In Vivo Cup Coverage Provided by Total Hip Arthroplasty for Dysplasia

The accuracy of using 2-dimensional anteroposterior pelvic radiography to assess acetabular cup coverage among patients with developmental dysplasia of the hip after total hip arthroplasty (THA) remains unclear in retrospective clinical studies. A group of 20 patients with developmental dysplasia of the hip (20 hips) underwent cementless THA. During surgery but after acetabular reconstruction, bone wax was pressed onto the uncovered surface of the acetabular cup. A surface model of the bone wax was generated with 3-dimensional scanning. The percentage of the acetabular cup that was covered by intact host acetabular bone in vivo was calculated with modeling software. Acetabular cup coverage also was determined from a postoperative supine anteroposterior pelvic radiograph. The height of the hip center (distance from the center of the femoral head perpendicular to the inter-teardrop line) also was determined from radiographs. Radiographic cup coverage was a mean of 6.93% (SD, 2.47%) lower than in vivo cup coverage for these 20 patients with developmental dysplasia of the hip (P<.001). However, both methods yielded highly correlated measurements for cup coverage (Pearson r=0.761, P<.001). The size of the acetabular cup (P=.001) but not the position of the hip center (high vs normal) was significantly associated with the difference between radiographic and in vivo cup coverage. Two-dimensional radiographically determined cup coverage conservatively reflects in vivo cup coverage and remains an important index (taking 7% underestimation errors and the effect of greater underestimation of larger cup size into account) for assessing the stability of the cup and monitoring for adequate ingrowth of bone. [Orthopedics. 2018; 41(1):e46-e51.].

Challenges in Total Hip Arthroplasty in the Setting of Developmental Dysplasia of the Hip

BACKGROUND

Developmental dysplasia of the hip (DDH) is a recognized cause of secondary arthritis, which may eventually lead to total hip arthroplasty (THA). An understanding of the common acetabular and femoral morphologic abnormalities will aid the surgeon in preparing for the complexity of the surgical case.

METHODS

We present the challenges associated with acetabular and femoral morphologies that may be present in the dysplastic hip and discuss surgical options to consider when performing THA. In addition, common complications associated with this population are reviewed.

RESULTS

The complexity of THA in the DDH patient is due to a broad range of pathomorphologic changes of the acetabulum and femur, as well as the diverse and often younger age of these patients. As such, THA in the DDH patient may offer a typical primary hip arthroplasty or be a highly complex reconstruction. It is important to be familiar with all the subtleties associated with DDH in the THA population. The surgeon must be prepared for bone deficiency when reconstructing the acetabulum and should place the component low and medial (at the anatomic hip center), and avoid oversizing the acetabular component. Femoral dysplasia is also complex and variable, and the surgeon must be prepared for different stem choices that allow for decoupling of the metaphyseal stem fit from the implanted stem version. In Crowe III and IV dysplasia, femoral derotation/shortening osteotomy may be required. Many complications associated with THA in the DDH patient may be mitigated with careful planning and surgical technique.

CONCLUSION

Performed correctly, THA can yield excellent results in this complex patient population.

Cementless acetabular component with or without upward placement in dysplasia hip: Early results from a prospective, randomised study

BACKGROUND

Total hip arthroplasty (THA) in developmental dysplasia of hip (DDH) is difficult for the abnormal acetabulum. The purpose of this study was to evaluate the difference of anatomic and upward placement of acetabular component during early stage.

METHODS

From April 2014 through June 2015, forty DDH patients (Crowe I to III, 42 hips) were prospectively randomized to either anatomic or upward group. Patient recorded diaries were collected. Radiographs were reviewed. WOMAC and Harris scores were tabulated from pre-operation to 12 months after surgery.

RESULTS

The patients' characteristics including age and body mass index (BMI) had no significant difference (P > 0.05). There were no statistically differences between two groups for surgery time, intraoperative blood loss, hemoglobin (Hb), blood transfusion, albumin decrease, length of stay-day, but surgery time and blood loss in patients with structural bone graft was much higher in anatomic group. The postoperative limb-length discrepancy (LLD) was also no difference, but limb lengthening was better in anatomic group (P = 0.042). The total hospital costs in the anatomic group were higher, but no significant differences. With regard to Harris and WOMAC score, there were significant improved after surgery in both groups, and the anatomic group was better in the value, but these differences were no statistically significant.

CONCLUSIONS

Acetabular reconstruction for DDH subluxation should be reconstructed as close to the actual acetabular location as possible, but an appropriate (<20 mm) upward placement that can achieve at least 70% native bone coverage of the acetabular implant is a valuable technique for early faster recovery.

The necessity to restore the anatomic hip centre in congenital hip disease

Total hip replacement (THR) is the treatment of choice for the patient suffering from end-stage hip osteoarthritis. In the presence of deformities due to congenital hip disease (CHD), THR is, in most of the cases, a difficult task, since the technique of performing such an operation is demanding and the results could vary. We present our experience and preferred strategies focusing on challenges and surgical techniques associated with reconstructing the dysplastic hip.