Schulterendoprothetik bei posttraumatischen Deformitäten durch Frakturfolgen

Mid-term results of a stemless ceramic on polyethylene shoulder prosthesis - A prospective multicentre study

INTRODUCTION

Early reports of stemless shoulder arthroplasty have shown promising clinical and radiological outcomes. The purpose of this study was to report on the mid-term results of an implant that utilises a ceramic humeral head.

METHODS

A prospective, consecutive, multicentre study of stemless shoulder prosthesis with a minimum of four years of follow-up was conducted between August 2009 and May 2012. The adjusted Constant-Murley Score (CMS), revision rate and presence of radiolucent lines were recorded at intervals.

RESULTS

A total of 207 patients were eligible for study inclusion; 62.8% were female and mean age was 64.8 years (range 30-86). Mean follow-up was 70.7 months (range 48-100), 73% underwent TSA and 27% hemiarthroplasty. The mean CMS improvement was 42.6 (p < 0.0001) at 48 months. Radiolucencies were present in 2.7% of humeral zones and 14% of glenoid zones at 48-month follow-up. The revision rate was 6.3% with rotator cuff failure (2.9%) the most common indication.

CONCLUSIONS

Mid-term results demonstrate that the studied stemless implant with a ceramic humeral head had clinical and radiological outcomes that are comparable to other reported studies.

Mid-term results with an anatomic stemless shoulder prosthesis in patients with primary osteoarthritis

OBJECTIVE

The introduction of a stemless prosthesis in shoulder arthroplasty represents a novel design whereby the proximal humerus is restored anatomically, while leaving the diaphysis of the humerus untouched. The aim of this study was to present the mid-term results of total evolutive shoulder system (TESS; Biomet^®), a stemless shoulder prosthesis.

METHODS

The study included 38 consecutive patients (18 men and 20 women; mean age: 66 years; range: 55-81 years) treated with shoulder arthroplasty between 2009 and 2011 with TESS for primary glenohumeral arthritis. Total shoulder arthroplasty (TSA) was performed in 28 cases (74%), hemi-shoulder arthroplasty (HSA) in 10 (26%). Constant score, active range of motion, patient satisfaction rate, and radiological assessment were analyzed. Mean time of follow-up was 37 months.

RESULTS

Constant score improved from 21.8 points (28.6 adjusted for age) preoperatively to 74.1 points (86.6 adjusted for age) postoperatively. Active range of motion increased significantly from the pre- to postoperative status. Eighty-nine percent were very satisfied or satisfied with shoulder replacement surgery. One cemented glenoid was revised due to aseptic loosening. None of the components were found to be loose at the final follow-up. No signs of stress shielding were seen.

CONCLUSIONS

This study shows promising results of this implant concept in the short- to mid-term. These results are comparable with the results achieved with long-established arthroplasty designs.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Radiological changes do not influence clinical mid-term outcome in stemless humeral head replacements with hollow screw fixation: a prospective radiological and clinical evaluation

Background

Stemless shoulder arthroplasty is a fairly new concept. Clinical and radiological follow-up is essential to prove implant safety and concept. This prospective single-centre study was performed to evaluate the influence of radiological changes on clinical mid-term outcome following stemless humeral head replacement with hollow screw fixation.

Methods

Short- and mid-term radiological and clinical evaluations were performed in 73 consecutive shoulders treated mainly for idiopathic and posttraumatic osteoarthritis with stemless humeral head arthroplasty including 40 hemi- (HSA) and 33 total shoulder arthroplasties (TSA). Operating times of stemless implantations were compared to 110 stemmed anatomical shoulder prostheses. Appearances of humeral radiolucencies or radiological signs of osteolysis or stress shielding were assessed on standardized radiographs. Patients’ clinical outcome was evaluated using the Constant score and patients’ satisfaction was documented.

Results

Radiological changes, detected in 37.0%, did not affect clinical outcome. Constant scores significantly improved from baseline to short and mid-term follow-up (p < 0.001). The majority of patients (96.2%) were satisfied with the procedure. No loosening of the humeral head component was detected during a mean follow-up of 58 months. Operating times were significantly shorter with stemless compared to stemmed implants (p < 0.001).

Conclusions

Clinical mid-term outcome after stemless humeral head replacement was not affected by radiological changes.

Trial registration

The institutional review board (St. Vincent Hospital Vienna; 201212_EK01; date of issue: 11.12.2012) approved the study. The trial was registered at ClinicalTrials.gov (NCT02754024). Retrospective registration.

[Periprosthetic humeral fractures: Strategies and techniques for osteosynthesis]

The prevalence of periprosthetic humeral fractures (PHF) is currently low and accounts for 0.6-2.4%. Due to an increase in the rate of primary implantations a quantitative increase of PHF is to be expected in the near future. The majority of PHF occur intraoperatively during implantation with an increased risk for cementless stems and when performing total arthroplasty. Additional risk factors are in particular female gender and the severity of comorbidities. In contrast, postoperative PHF mostly due to low-energy falls, have a prevalence between 0.6% and 0.9% and are significantly less common. The prognosis and functional outcome following revision by open reduction internal fixation (ORIF) essentially depend on a thorough assessment of the indications for revision surgery, the operative treatment and the pretraumatic functional condition of the affected shoulder. In the armamentarium of periprosthetic ORIF of the humerus cerclage systems and locking implants as well as a combination of both play a central role. In comminuted fractures with extensive defect zones, severely thinned cortex or extensive osteolysis a biological augmentation of the ORIF should be considered. In this context when the indications are correctly interpreted, especially in the case of a stable anchored stem, various groups have reported that a high bony union rate can be achieved. As the treatment of PHF is complex it should be performed in dedicated centers in order to adequately address potential comorbidities, especially in the elderly population.

[Periprosthetic humeral fractures: Strategies and techniques of revision arthroplasty]

The primary aims when performing revision arthroplasty of periprosthetic humeral fractures (PHF) are preservation of bone stock, achieving fracture healing and preserving a stable prosthesis with the focus on regaining the preoperative shoulder-arm function. The indications for revision arthroplasty are given in PHF in combination with loosening of the stem. In addition, further factors must be independently clarified in the case of an anatomical arthroplasty. In this context secondary glenoid erosion as well as rotator cuff insufficiency are potential factors for an extended revision procedure. For the performance of revision surgery modular revision sets including long stems, revision glenoid and metaglene components as well as plate and cerclage systems are obligatory besides the explantation instrumentation. Despite a loosened prosthesis, a transhumeral removal of the stem along with a subpectoral fenestration are often required. Length as well as bracing of revision stems need to bridge the fracture by at least twice the humeral diameter. Moreover, in many cases a combined procedure using an additional distal open reduction and internal fixation (ORIF) plus cable cerclages as well as biological augmentation might be needed. Assuming an adequate preparation, the experienced surgeon is able to achieve a high fracture union rate along with an acceptable or even good shoulder function and to avoid further complications.

SPECT/CT demonstrates the osseointegrative response of a stemless shoulder prosthesis

BACKGROUND

This study evaluates bone remodeling processes in the proximal humerus induced by the implantation of a stemless shoulder prosthesis with regard to time of response and type and extent of bone turnover.

METHODS

Twenty-eight patients with primary osteoarthritis of the shoulder undergoing a stemless shoulder arthroplasty were prospectively evaluated. The local metabolic bone activity in 5 regions of interest (ROIs 1-5) around the implant and in 1 reference region (ROI ref.) in the humeral diaphysis was analyzed after the application of technetium Tc 99m DPD using single-photon emission computed tomography integrated with multidetector computed tomography (SPECT/CT). The study cohort was divided into 4 groups according to the timing of the most recent follow-up appointment to evaluate the primary osseointegrative response after surgery. The bone uptake values were expressed in target (ROIs 1-5) to nontarget (ROI ref.) ratios.

RESULTS

No difference within the 4 subgroups with respect to the time of local metabolic bone activity in the ROIs was found at 90 days after surgery. The highest initial metabolic activity and most temporal modifications were found in ROI 1, which was localized in the superior segment of the stem.

CONCLUSIONS

SPECT/CT data suggest that the primary osseointegration of a stemless shoulder prosthesis is almost completed 3 months after implantation. Variations in metabolic activity pattern in the ROIs during follow-up may be caused by different loading conditions of the bone.

Anatomic shoulder arthroplasty for treatment of proximal humerus malunions

BACKGROUND

Malunion of proximal humeral fractures complicated by damage to the glenohumeral cartilage and injury to the joint capsule and rotator cuff can include treatment requiring anatomic shoulder arthroplasty. This study defines results and complications of this procedure and identifies factors associated with success or failure.

METHODS

From 1976 to 2007, 109 patients underwent shoulder arthroplasty for proximal humerus malunions. Ninety-five met the criteria for analysis with a mean follow-up period of 9.2 years. Fracture types according to the Neer classification were two part in 20, three part in 37, four part in 31, and head splitting in 2, with 16 fracture-dislocations. Hemiarthroplasty was performed in 45 patients, with 50 undergoing total arthroplasty.

RESULTS

Pain scores improved from 7.8 to 3.1 (P < .001). The mean active elevation and external rotation improved from 69° to 109° and from 8° and 39°, respectively (P = .001). Of 31 patients with available radiographs, 20 had healed tuberosity osteotomies. Sixteen complications required 10 reoperations, including 6 of 9 patients with severe postoperative instability. There were 57 excellent or satisfactory results by use of the Neer rating. No patient, injury pattern, previous treatment, surgical, or radiologic variation was significantly associated with an increased risk of an unsatisfactory result, except for severe postoperative instability. Kaplan-Meier survivorship for reoperation, in 109 shoulders, was 94.8% (95% confidence interval, 90.5%-99.4%) at 5 years and 90.1% (95% confidence interval, 83.6%-97.1%) at 10 and 15 years.

CONCLUSION

Anatomic shoulder arthroplasty improves pain and motion. Surgery is complex. Tuberosity osteotomies often heal. Postoperative instability is the most common complication leading to reoperation and is usually associated with rotator cuff and shoulder capsule injury.

[Indication for primary fracture prosthesis of the shoulder]

Although fractures of the proximal humerus are one of the most common osteoporotic fracture types, no generally accepted treatment algorithm exists in the current literature. For young patients with high functional demands and good rehabilitation potential, we recommend humeral head salvage therapy. If symptomatic humeral head necrosis occurs, the implantation of an anatomic endoprothesis is possible on a secondary basis. For patients with a biological age > 70 years suffering from a persisting defect of the rotator cuff along with a humeral head fracture or from a multiple fragment fracture of the humeral head, we increasingly prefer implantation of a reverse shoulder prosthesis due to good clinical results. However, because of technical aspects and a high complication rate, treatment using the reverse fracture prosthesis should be reserved for surgeons with expertise in this particular field. After analyzing the fracture- and patient-specific risk factors and performance expectations, the trauma surgeon can select the best individual therapy with the patient.

Stemless shoulder prosthesis versus conventional anatomic shoulder prosthesis in patients with osteoarthritis: a comparison of the functional outcome after a minimum of two years follow-up

Background

The stemless shoulder prosthesis is a new concept in shoulder arthroplasty. To date, only a few studies have investigated the results of this prosthesis. The aim of this study was to investigate the clinical and radiological midterm results of this implant in comparison with a standard anatomic stemmed shoulder prosthesis.

Materials and methods

The Constant score, the DASH score, the active range of motion (abduction, anteversion, external rotation), and the radiological results were examined in 82 patients with primary osteoarthritis of the shoulder treated with either the Total Evolutive Shoulder System^® (Biomed, France) stemless shoulder prosthesis or the Affinis^® (Mathys, Switzerland) stemmed shoulder prosthesis to detect possible differences in the functional outcome and to evaluate radiological properties of the implants. Patients were examined before and 32 ± 4 months after surgery.

Results

There was no significant difference in the Constant scores of the groups treated with the stemless shoulder prosthesis (65.0 ± 11.0 points) and the stemmed shoulder prosthesis (73.2 ± 11.3 points; P = 0.162). The estimated blood loss (P = 0.026) and the mean operative time (P = 0.002) were significantly lower in the group with the stemless shoulder prosthesis.

Conclusions

The use of the stemless shoulder prosthesis yielded good results which, in a mid-term follow-up, were comparable with those provided by a standard anatomic shoulder prosthesis. Further investigations are needed regarding the long-term performance of this prosthesis.

Predictive factors for functional outcome and failure in angular stable osteosynthesis of the proximal humerus

INTRODUCTION

Angular stable osteosynthesis has become the gold standard in the operative treatment of proximal humeral fractures. The aim of this article is to determine the indications for osteosynthesis versus primary arthroplasty based on clinical and radiological parameters.

METHODS

A total of 368 surgically treated proximal humeral fractures were reviewed. Preoperative X-rays were used to evaluate the displacement and vascularity of the humeral head (according to the Hertel criteria) and the AO (Arbeitsgemeinschaft für Osteosynthesefragen) fracture type. Postoperative X-rays were analysed to assess the quality of the reduction, the reconstruction of the medial hinge and the displacement of the tuberosities. Follow-up X-rays were used to evaluate healing progress, the occurrence of avascular necrosis, loss of reduction and implant related failures. The American Shoulder and Elbow Surgeons score (ASES score) was used to evaluate the functional outcome. Correlations between a set of variables, type of treatment and eventual outcome were verified in both univariate and multivariate settings, with the significance rate set at p<0.05.

RESULTS

In total, 307 shoulders were evaluated. Mean follow-up was 4.3 years and showed a 15.3% failure rate, a 23.8% re-operation rate and a mean ASES score of 75.3. Better results were noted in patients who were younger at the time of surgery. More displaced fractures, AO type C fractures, varus fracture configuration and reduced head vascularity all led to a worse outcome. Anatomical reduction correlated with better results. Articular fractures had better results when treated with a plate.

CONCLUSION

Surgical treatment of proximal humeral fractures remains difficult, with a failure rate of 15.3% and a re-operation rate of 23.8% at 4.3 years. A significantly displaced varus articular fracture in the older patient results in the worst outcome.

Humeral cementless surface replacement arthroplasties of the shoulder: an experimental investigation on their initial fixation

Cementless surface replacement arthroplasties are increasingly being used to treat arthritic humeral heads. These implants are designed to provide narrow bone resection, making a later revision easier. However, no clear evidence exists as to whether their initial fixation is sufficient for bony ingrowth. The aim of our in vitro study was to characterize the relative micromotion of two resurfacing implants with essentially different bone-facing geometries. Both systems were implanted into 10 human humeral specimens and micromotion was measured under a cyclic torque application of up to ±1.75 Nm. The mean relative rotary motion resulted in a significant difference (p = 0.036), which was attributed to design differences of central stabilizers featuring both implants. A conversion of rotary motions into relative micromotions, using recently measured moments acting on these implants during daily activities of living, nullified this difference (p = 0.088). However, depending on the shoulder load case considered, a clear difference appeared (p = 0.031-0.045). In conclusion, both resurfacing implants are capable of achieving sufficient initial fixation on the humeral head and perform relative micromotions in a range considered safe for bony ingrowth. Patient-related parameters do not appear to influence the initial fixation of these implants.

[Biomechanical investigation on refixation of tuberosities on shoulder prostheses. Does refixation with different suture materials offer enough stability?]

BACKGROUND

Elderly patients suffering from complex, non-reconstructable fractures of the proximal humerus are commonly treated by primary implantation of a shoulder endoprosthesis. One of the most critical factors for success or failure of treatment is still the refixation of the tuberosities.

METHOD

Using sheep infraspinatus tendons with attached tuberosities three different suture materials were investigated. For 2 of the suture materials 4 tests were accomplished and 5 tests were carried out for the third suture material. A material testing machine was used to perform cyclic loading tests (20 mm/min, Fmin=50 N, Fmax=100 N, respectively after 50 cycles: Fmax+50 N until failure).

RESULTS

The results showed large variations in the average maximum forces (152.4 N for suture 1, 219.9 N for suture 2 and 452.3 N for suture 3). All tests showed a high initial lengthening and caused incision-like defects in the bone or tendon and led to failure and high displacement of the tuberosities.

CONCLUSION

Due to these results suture materials have a limited usefulness for refixation of tuberosities as an increased risk of obstruction for bony consolidation can result.