A short-stem hip implant with metaphyseal anchorage in patients with developmental dysplasia of the hip

Mid-term results of total hip arthroplasty with anatomical ultra-short cementless stem in patients with developmental dysplasia of the hip Crowe type II

The aim of this study was to present the mid-term results of ultra-short cementless stem total hip arthroplasty (THA) in patients with Crowe type II developmental dysplasia of the hip. The study consists of 68 patients (75 THAs) with a Proxima stem implanted between 2006 and 2015. The clinical results include Harris Hip Scores. Radiological follow-up reports on stem migration, bony trabecular development and radiolucent lines. Kaplan-Meier survival analysis was performed. The mean age of patients was 48.4 years, with a mean follow-up 114 months. The average Harris Hip Score improved significantly from 45.1 preoperatively to 97.6 at the final evaluation (p < 0.001). Stem migration was observed in five hips (in all of them up to the 6th postoperative month, without any further progression of migration or radiological loosening). Bony trabecular development was detected in modified Gruen zones (1, 2, 4, 6, 7 for Proxima stem): in zone 1 (0%), 2 (49.3.0%), 4 (38.7%), 6 (82.7%), 7 (0%). Radiolucent lines were observed around one cup (DeLee and Charnley zone I) and three stems (none was loose, all three with fibrous stable fixation). Complications were found in three hips (4.0%): intraoperative periprosthetic femoral fracture (threated with cerclage wire) in two hips and squeezing hip in one patient (with perioperative ceramic inlay breakage and exchange). No hip was revised. The implant survival was 100.0% both clinically and radiologically. Observations in the mean follow-up of 114 months show that the results (clinical and radiological) of the Proxima stem in patients with Crowe type II DDH are promising.

Effect of short stem alignment on initial fixation, stress transfer, and failure risk

BACKGROUND

Short stems are advantageous for revision as they preserve autogenous bone. At present, the method of short-stem installation is determined based on the surgeon's experience.

OBJECTIVE

To provide the guideline for installing a short stem, we aimed to investigate the alignment effect on the initial fixation of the stem, stress transfer, and the risk of failure numerically.

METHODS

Models in which the caput-collum-diaphyseal (CCD) angle and flexion angle were hypothetically changed based on the two clinical cases of hip osteoarthritis were analyzed using the non-linear finite element method.

RESULTS

The medial settlement of the stem increased in the varus model and decreased in the valgus model. With varus alignment, the stresses acting on the femur were high in the distal to the femoral neck. In contrast, the stresses in the proximal to the femoral neck tend to be higher with valgus alignment, although the difference in the femur stress between varus and valgus alignment was slight.

CONCLUSION

Both initial fixation and stress transmission are lower when the device was placed in the valgus model than in the actual surgical case. In order to obtain initial fixation and suppress stress shielding, it is essential to extend the contact area between the medial portion of the stem and the femur along the bone axis, and to ensure adequate contact between the lateral portion of the stem tip and the femur.

Future of total hip arthroplasty with the Metha short stem in modern surgeries

The aim of the study was to analyse the results of uncemented total hip replacement, using the Metha (metaphyseal) stem. A total of 158 patients (70 females and 88 males) were qualified to the study and submitted to total hip arthroplasty (183 procedures altogether), using the Metha stem. The mean age of the patients on the day of surgery was 51.7 years (the range from 17 to 69 years). The mean follow up period was 9.2 years (the range from 5 to 13.5 years). Preoperative assessments gave poor scores, according to the Merle d’Aubigne and Postel classification, modified by Charnley. The average improvement after surgery, according to the used scale, was 6.9 points. A very good outcome was recorded in 154 cases (84.2%), a good outcome was achieved in 20 cases (10.9%) and a poor outcome was confirmed in 9 cases, while no satisfactory case was observed. Poor outcomes were associated with implant loosening. Extraskeletal ossification was noted in 10 cases (5.5%). According to the Kaplan–Meier estimator, the 10-year survival was 93.2% and 97.3% for the whole implant and the stem alone, respectively. 1. Our follow-up period of more than 9 years on the average, indicates that Metha stems produce excellent clinical and functional results in operated young patients with advanced degenerative changes of the hip joint. 2. Assuming a proper qualification for the procedure, the absence of complications and a correct surgical technique, which is slightly more difficult, when compared to standard stem implantation, the risk of aseptic loosening is fairly negligible.

Calcar-guided short-stem total hip arthroplasty: Will it be the future standard? Review and perspectives

Short stems in total hip arthroplasty (THA) are becoming increasingly popular. In Germany, already 10.4% of all primary THAs are performed using a cementless short stem. The concept of modern, calcar-guided, short stems aims for an individualized reconstruction of the hip anatomy by following the calcar of the femoral neck, a bone- and soft-tissue-sparing implantation technique, and physiological loading. The stem design uses either metaphyseal fixation alone or additional diaphyseal anchoring, depending on the stem alignment and indication. These individualized anchorage types increase the potential indications for the safe use of a short stem. The design features may account for potential advantages of current short stem implants compared with earlier short-stem designs, particularly in cases of reduced bone quality or osteonecrosis of the femoral head and femoral neck fractures. The implantation technique, however, requires distinct knowledge regarding the characteristics of varus and valgus positioning, with the potential for clinical consequences. A learning curve for surgeons new to this technique must be taken into account. Cortical contact with the distal lateral cortex appears to be crucial to provide sufficient primary stability, and the use of intraoperative imaging to identify “undersizing” is highly recommended. Current results of several national registries indicate that calcar-guided short stems are among the most successful implants in terms of mid-term survivorship. However, long-term data remain scarce. This review introduces the characteristics of calcar-guided short-stem THA and summarizes the current evidence.

The clinical outcome of the Metha short hip stem: a systematic scoping review

INTRODUCTION

Short femoral stems were designed to bridge the gap between conventional straight design stems and hip resurfacing prostheses in total hip arthroplasty (THA). A number of clinical trials have been recently conducted to assess the clinical and safety profile of the cementless, colarless, tapered Metha short hip stem in young or active middle-aged individuals.

METHODS

A systematic scoping review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. 4 reviewers independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms "short" AND "hip" AND "stem".

RESULTS

From the initial 773 studies we finally chose 12 studies after applying our inclusion-exclusion criteria. The number of operated hips that were included in these studies was 5048 (mean BMI range: 22.7-35.2, mean age range: 44.4-60.4 years, mean follow-up range: 2-9 years). The mean modified Coleman methodology score was 52.3/100, while it ranged from 31/100 to 63/100. All mean clinical outcome scores that were used in the studies illustrated significant postoperative improvement when compared with the respective initial values. The revision rate of the Metha stem for component-related reasons was 2.5%, while the rate of major complications not requiring revision of the Metha stem was 2.8%.

CONCLUSIONS

The Metha stem performs well in young or active middle-aged THA patients. Further studies are required for the assessment of the long-term results.

Mid-term results of short-stem total hip arthroplasty in patients with Crowe type I and II developmental dysplasia of the hip

BACKGROUND

This study aimed to evaluate the clinical and radiographic mid-term results of short-stem THA in patients with DDH.

METHODS

We reviewed 32 cases that underwent Metha stem between November 2010 and February 2015. WOMAC scores, Oxford Hip Scores (OHS) and Harris Hip Scores (HHS) were recorded to evaluate the clinical results. The appearance of bone trabeculae development and stress shielding was analyzed.

RESULTS

The mean age of patients was 50.3 years (33-67) with the mean follow-up of 77 months (60-106). According to Crowe classification, 13 cases were graded as Crowe I and 19 cases as Crowe II. According to Dorr classification, 17 cases were graded as Dorr A and 15 cases as Dorr B. The postoperative WOMAC scores decreased, and OHS and HHS increased significantly compared with preoperative (p < 0.001). The caput-column-diaphysis angles decreased significantly (p < 0.001) and limb length discrepancy decreased significantly (p = 0.013) after surgery. The radiographic change around the stem showed bone trabeculae development at zones 1 (93.9%), 2 (93.9%), 3 (25%), 5 (6.3%), 6 (96.9%) and 7 (90.6%). There was grade 1 stress shielding in 30 cases (93.9%). There was no stem subsidence greater than 2 mm in all hips, no sciatic nerve injury or no dislocation. Neither acetabulum nor femoral stem was defined as definite loosening, and none of the implants was revised.

CONCLUSIONS

The short stem showed promising mid-term clinical results in patients with DDH. The radiographic results demonstrated that the short stem provided physiological proximal load transfer with less stress shielding, being a useful alternative for femoral reconstruction.

Is a short stem suitable for patients with hip dysplasia? A report on technical problems encountered during femoral reconstruction

INTRODUCTION

A wide variety of stems have been used for the treatment of osteoarthritis secondary to advanced hip dysplasia. Since evidence for using short stems in dysplastic hips is limited, we planned to analyse the technical problems encountered when reconstructing the proximal femur of patients with osteoarthritis secondary to congenital dysplasia of the hip treated with total hip arthroplasty (THA) using a type 2B short stem.

METHODS

We prospectively analysed 17 patients (22 hips) treated with primary THA performed with a single-branded short uncemented stem with metaphyseal fixation (MiniHip™; Corin). We excluded cases in which other type of stems were used, or in which retrospective data was only available. Mean follow-up was 41.22 months (minimum 24). We analysed clinical outcome using the modified Harris Hip Score (mHHS) and pain using the visual analogue scale (VAS). Radiographs were examined in order to determine causes of complications and revision surgery.

RESULTS

All patients showed statistically significant improvement when preoperative and postoperative values for mHHS (54.19 vs. 94.57; p = 0.0001) and for pain VAS (8.71 vs. 0.71; p = 0.0003) were compared. No cases of thigh pain, instability or infection were found. 1 case of acetabular cup loosening and 1 case of periprosthetic fracture were diagnosed at 8 months and 45 days, respectively. Overall survival was 84.7% at 5 years (CI 95%, 64.4-105.3) with revision for any reason as an end point. When stem performance was separately evaluated, it showed a survival rate of 100% at 5 years with revision for aseptic loosening as an end point.

CONCLUSIONS

THA with a type 2B short stem for the treatment of dysplastic osteoarthritis showed very few technical intraoperative problems, being a useful alternative for femoral reconstruction.

Bone-preserving total hip arthroplasty in avascular necrosis of the hip-a matched-pairs analysis

PURPOSE

Short-stem hip arthroplasty has the potential advantage of femoral bone stock preservation, especially in view of the expected revisions in the often relatively young patients. Despite short-stem hip prosthesis are increasingly used for total hip arthroplasty, there are no sufficient mid- and long-term results especially for patients with avascular femoral head osteonecrosis. The present study investigates mid-term functional results as well as the revision rate following implantation of a short-stem prosthesis.

METHODS

In the period 06/2005 until 12/2013, a total of 351 short-stem hip prostheses were implanted. The study included 331 complete data sets. A retrospective analysis was performed using the Oxford Hip Score. All revisions were registered.

RESULTS

In a total of 331 prostheses, the Oxford Hip Score was "excellent" in 66.2%, "good" in 12.7%, "fair" in 13.0%, and "poor" in 8.2% with a mean follow-up of 57.4 months (SD ± 29.8; range 24-115). In 26 cases, aseptic osteonecrosis of the hip was the indication (7.9%). The Oxford Hip Score was "excellent" in 66.7%, "good" in 0.0%, "fair" in 20.8%, and "poor" in 12.5%. The cumulated five year survival rate was 96.7%.

CONCLUSION

In mid-term observation, the Metha® short-stem prosthesis shows no disadvantage in functional outcome and in survival time compared to a standard hip stem. Providing a correct indication, the Metha® short stem is a valuable option in total hip arthroplasty for younger patients with avascular osteonecrosis of the femoral head. Evaluation has shown no significant differences between aseptic osteonecrosis and other indications.