Mid- and long-term clinical results of the Elektra and Moovis prosthesis for trapeziometacarpal joint replacement

BACKGROUND

Total joint arthroplasty as a surgical treatment option for trapeziometacarpal joint arthritis is recently revived. The aim of this study is to report on mid- and long-term results of the Elektra (single-mobility) and Moovis (dual-mobility) prosthesis for treatment of primary thumb carpometacarpal joint arthritis.

METHODS

In this retrospective, monocentric, descriptive cohort study, 31 prostheses were evaluated that were implanted by a single surgeon in 26 patients between 2009 and 2019. Indication for surgery was trapeziometacarpal joint osteoarthritis (Eaton/Littler Stage II and III). Clinical and radiological follow-up was performed at a minimum of 24 months. The postoperative assessment included range of motion, pain, strength as well as functional scores (DASH, MHQ). Implant survival and complications were the primary endpoints.

RESULTS

10 Elektra and 21 Moovis prostheses were implanted between 2009 and 2019 with a mean follow-up of 74.2 months in the Elektra and 41.4 months in the Moovis group. The average patients' age at surgery was 64 years. Postoperative pain levels (VAS 0-10) were below 2 at rest and under stress in both groups. Grip/pinch strength and range of motion showed results comparable to the contralateral hand. Opposition was excellent with an average Kapandji index of 9.6 in both groups. Elektra achieved slightly better functional scores in the DASH and MHQ score. Satisfaction was high in both groups, and 96% of the patients would recommend the procedure. Metacarpophalangeal hyperextension > 15° was seen in 3 patients per group preoperatively and was corrected to < 5° post-surgery. 3 Elektra prostheses were revised due to cup loosening and dislocation for cup and/or neck replacement or secondary trapeziectomy. 1 Moovis prosthesis was revised with an exchange of the neck to a larger size due to restricted movement. After the mean follow-up of 7.9 years in Elektra and 3.5 years in MOOVIS, cumulative survival was 68.6% vs. 95.2%, respectively.

CONCLUSIONS

In this mid- to long-term retrospective analysis, total joint arthroplasty in primary trapeziometacarpal joint arthritis results in low pain levels, excellent mobility and clinical function. Patient satisfaction is overall high. While revision due to cup loosening occurred more often in patients with single-mobility implants, no cases of dislocation or loosening of components were observed in the dual-mobility group.

TRIAL REGISTRATION

The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of the Medical Faculty of Heidelberg University, reference number S-150/2020.

Analysis of factors among 30-day and 1-year mortality rates in patients with borderline stable-unstable intertrochanteric hip fracture

OBJECTIVE

This study aimed to evaluate the possible effects of surgical procedures on mortality and to identify the possible risk factors for mortality in the management of geriatric hip fractures.

METHODS

A total of 191 patients (105 women and 86 men; mean age 82.26±9.681 [60-108] years) with AO/OTA 31A2.2 intertrochanteric fractures and treated with sliding hip screw, proximal femoral nail, or hemiarthroplasty were included in this retrospective cohort study. The treatment type was decided by the responsible surgeon according to the patients' pre-injury activity level, bone quality, and features of the fracture. Age, sex, type of fracture, type of surgery performed, American society of anesthesiology (ASA) grade, type of anesthesia, time to surgery, type of physical therapy, length of hospital stay, and number of comorbidities were documented. We evaluated the 30-day and 1-year mortality of patients treated with sliding hip screw (SHS), proximal femoral nail antirotation (PFN-A), or hemiarthroplasty and identified the possible risk factors for mortality.

RESULTS

A total of 49 patients underwent SHS, 58 underwent PFN-A, and 84 underwent hemiarthroplasty. Of these, 2 patients with SHS, 2 with PFN-A, and 11 with hemiarthroplasty died within 30 days after surgery, whereas 7 patients with SHS, 15 with PFN-A, and 23 with hemiarthroplasty died 1 year after surgery. The 30-day and 1-year overall mortality rates were 7.9% and 23.6%, respectively. Both the 30-day and 1-year mortality risks were higher in patients undergoing hemiarthroplasty than in patients undergoing SHS (p=0.068 versus 0.058). The 30-day mortality was higher in patients receiving general anesthesia than in those receiving combined spinal and epidural anesthesia (p=0.009). The 1-year mortality risk was higher in patients with ASA grade 4 than in those with grade 1 and 2 (p=0.045). Advanced age (p=0.022) and male sex (p=0.007) were also found to be the risk factors for 1-year mortality.

CONCLUSION

We demonstrated that higher ASA grade, male sex, general anesthesia, and hemiarthroplasty procedures are associated with higher mortality rates in elderly patients with hip fractures. Thus, we highly recommend orthopedic surgeons to consider all these factors in the management of intertrochanteric hip fractures in the geriatric population.

LEVEL OF EVIDENCE

Level IV, Prognostic Study.

Medium term outcomes of the Universal 2 total wrist arthroplasty in patients with degenerative or posttraumatic osteoarthritis of the wrist

This retrospective study reports medium term outcomes of 14 total wrist arthroplasties in patients with especially, non-rheumatoid, degenerative osteo- arthritis and post-traumatic osteoarthritis with a mean follow up of 5 to 10 years. Information of fourteen patients, 6 men and 8 women with a mean age of 61 years, was collected before and after total wrist arthroplasty (Universal 2 prosthesis, Integra) carried out by a single surgeon. Pre-operative mobility was determined by range of motion and compared to post- operative range of motion. Post-operative function was determined using the DASH (The disabilities of the arm, shoulder and hand) score and the PRWE (patient-rated wrist evaluation and grip strength) score. Grip force between the operated and non- operated hand were compared postoperatively. Three patients experienced complications. Range of motion improved post-operatively, although not significantly, due to an increase in palmar flexion. The mean DASH score was 20% and the mean total PRWE was 54%. This study shows that total wrist arthroplasty, using the Universal 2 wrist prosthesis, gives reasonable results (survival rate 84%) by decreasing pain while preserving range of motion in patients with degenerative osteoarthritis of the wrist after 5 years. However the 10-year survival rate decreases steeply to an unsatisfying 35%.

Lower Success Rate of Débridement and Implant Retention in Late Acute versus Early Acute Periprosthetic Joint Infection Caused by Staphylococcus spp. Results from a Matched Cohort Study

BACKGROUND

Surgical débridement, antibiotics and implant retention (DAIR) is currently recommended by international guidelines for both early acute (postsurgical) and late acute (hematogenous) periprosthetic joint infections (PJIs). However, due to a different pathogenesis of infection, a different treatment strategy may be needed.

QUESTIONS/PURPOSES

(1) Compared with early acute PJIs, are late acute PJIs associated with a higher risk of DAIR failure? (2) When stratified by microorganism, is the higher risk of failure in late acute PJI associated with Staphylocococcus aureus infection? (3) When analyzing patients with S. aureus infection, what factors are independently associated with DAIR failure?

METHODS

In this multicenter observational study, early acute and late acute PJIs treated with DAIR were retrospectively evaluated and matched according to treating center, year of diagnosis, and infection-causing microorganism. If multiple matches were available, the early acute PJI diagnosed closest to the late acute PJI was selected. A total of 132 pairs were included. Treatment success was defined as a retained implant during follow-up without the need for antibiotic suppressive therapy.

RESULTS

Late acute PJIs had a lower treatment success (46% [60 of 132]) compared with early acute PJIs (76% [100 of 132]), OR 3.9 [95% CI 2.3 to 6.6]; p < 0.001), but the lower treatment success of late acute PJIs was only observed when caused by Staphylococcus spp (S. aureus: 34% versus 75%; p < 0.001; coagulase-negative staphylococci: 46% versus 88%; p = 0.013, respectively). On multivariable analysis, late acute PJI was the only independent factor associated with an unsuccessful DAIR when caused by S. aureus (OR 4.52 [95% CI 1.79 to 11.41]; p < 0.001).

CONCLUSIONS

Although DAIR seems to be a successful therapeutic strategy in the management of early acute PJI, its use in late acute PJI should be reconsidered when caused by Staphylococcus spp. Our results advocate the importance of isolating the causative microorganism before surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

[The Risk of Total Joint Replacement Infectious Complications in Relation to the UHMWPE Particle Adhesion Area]

PURPOSE OF THE STUDY Periprosthetic joint infection is a major complication which in most of the cases requires a long-term administration of antibiotics and often necessitates undergoing multiple challenging surgeries. Bacterial adhesion to foreign material is one of the key risk factors associated with periprosthetic joint infection. The foreign material with large adhesion area might be also the UHMWPE (Ultrahigh molecular weight polyethylene) particles released during the wear process from the surface of articulating components. The purpose of this study is to evaluate potential adhesion areas of wear particles in relation to diverse distribution of the size and shapes of wear particles in periprosthetic tissue and to assess an increase in the risk of infectious complications associated with an increase in the adhesion area of wear particles. MATERIAL AND METHODS The size and morphology of model and real UHMWPE particles were determined with the use of light microscopy and scanning electron microscopy. By determining the morphological descriptors, the surfaces of individual particles for different distributions of polyethylene particles were calculated. When measuring the model wear particles, 6 model situations were simulated, in which comparisons with the control measurement by the BET (Brunauer-Emmet-Teller) method were made. RESULTS The variability of individual morphological descriptors demonstrates the effect on the total surface of particles. The calculated coefficient defines how many times the particle surface increases when corrected to the given descriptor (elongation, flattening, roughness, porosity). The total area of real wear particles at 1 year is 4,622 cm2, at 20 years it is 92,440 cm2. Based on our calculations, the area of particles where a biofilm is actually formed (approximately 50 bacteria may adhere to a particle of 3µm in diameter) is 809.5 cm2 at 1 year and 16,190 cm2 at 20 years. DISCUSSION According to the measurements, the size of the potential adhesion area of metal parts and polyethylene particles becomes equal already after several weeks of endoprosthesis usage and after a few years it is many times larger. The question is whether the risk of bacterial adhesion, i.e. also the risk of infectious complications of TEP actually increases. The clinical practice suggests that the number of infections e.g. 10, 15 or 20 years after the primary implantation is not statistically higher, despite the confirmed growth of potential adhesion area in the form of UHMWPE particles. This fact could be explained by a partially equal regulatory pathway of infection and polyethylene disease. The immune system stimulated by wear particles might better resist the hematogenic infection. CONCLUSIONS The study outcomes clearly indicate that the area of polyethylene wear particles considerably increases over time. In spite of the fact that only approximately 10% of wear particles show parameters (also with respect to the size of particles and bacteria) for potential bacterial adhesion, this area is many times larger than the area of metal parts of the endoprosthesis. Key words: UHMWPE particle, adhesion, biofilm, wear, TJR infection.

Effects of vitamin E incorporation in polyethylene on oxidative degradation, wear rates, immune response, and infections in total joint arthroplasty: a review of the current literature

Highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) was introduced to decrease wear debris and osteolysis. During cross-linking, free radicals are formed, making highly cross-linked polyethylene vulnerable to oxidative degradation. In order to reduce this process, anti-oxidant vitamin E can be incorporated in polyethylene. This review provides an overview of the effects of vitamin E incorporation on major complications in total joint arthroplasty: material failure due to oxidative degradation, wear debris and subsequent periprosthetic osteolysis, and prosthetic joint infections. Secondly, this review summarizes the first clinical results of total hip and knee arthroplasties with vitamin E incorporated highly cross-linked polyethylene. Based on in vitro studies, incorporation of vitamin E in polyethylene provides good oxidative protection and preserves low wear rates. Incorporation of vitamin E may have the beneficial effect of reduced inflammatory response to its wear particles. Some microorganisms showed reduced adherence to vitamin E-incorporated UHMWPE; however, clinical relevance is doubtful. Short-term clinical studies of total hip and knee arthroplasties with vitamin E-incorporated highly cross-linked UHMWPE reported good clinical results and wear rates similar to highly cross-linked UHMWPE without vitamin E.

Etiology of Above-knee Amputations in the United States: Is Periprosthetic Joint Infection an Emerging Cause?

BACKGROUND

Above-knee amputation (AKA) is a morbid procedure and is performed for a number of conditions. Although AKA is usually performed for dysvascular disease, trauma, and malignancy, AKA is also considered in patients who have failed multiple salvage attempts at treating periprosthetic joint infection (PJI) of TKA. Although aggressive measures are being taken to treat PJI, the huge volume of TKAs might result in a large number of AKAs being performed for PJI in the United States. However, the national trends in the incidence of AKAs from different etiologies and the relative contribution of different etiologies to AKA are yet to be studied.

QUESTIONS/PURPOSES

(1) What are the temporal trends in the incidence of AKAs (from all causes) in the US population from 1998 to 2013? (2) What are the temporal trends in the incidence of AKAs by etiology (dysvascular disease, trauma, malignancy, and PJI)? (3) What are the temporal trends in the relative contribution of different etiologies to AKA?

METHODS

Using the Nationwide Inpatient Sample (NIS) from 1998 to 2013, AKAs were identified using International Classification of Diseases, 9 Revision (ICD-9) procedure code 84.17. The NIS database is the largest all-payer database in the United States containing information on approximately 20% of all the hospital admissions in the country. As a result of its sampling design, it allows for estimation of procedural volumes at the national level. All AKAs were grouped into one of the following five etiologies in a sequential manner using ICD-9 diagnosis codes: malignancy, PJI, trauma, dysvascular disease (peripheral vascular disease, diabetic, or a combination), and others. All of the numbers were converted to national estimates using sampling weights provided by the NIS, and the national incidence of AKAs resulting from various etiologies was calculated using the US population as the denominator. Poisson and linear regression analyses were used to analyze the annual trends.

RESULTS

From 1998 to 2013, the incidence of AKAs decreased by 47% from 174 to 92 AKAs per 1 million adults (incidence rate ratio [IRR]; change in the number of AKAs per 1 million adults per year; 0.96; 95% confidence interval [CI], 0.96-0.96; p < 0.001). The incidence of AKAs resulting from PJI increased by 263% (IRR, 1.07; 95% CI, 1.06-1.07; p < 0.001). An increase was also observed for AKAs from malignancy (IRR, 1.01; 95% CI, 1.00-1.02; p = 0.007), although to a smaller extent. AKAs from dysvascular causes (IRR, 0.96; 95% CI, 0.95-0.96; p < 0.001) and other etiologies (IRR, 0.97; 95% CI, 0.96-0.97; p < 0.001) decreased. There was no change in the incidence of AKAs related to trauma (IRR, 1.00; 95% CI, 0.99-1.00; p = 0.088). The proportion of AKAs resulting from PJI increased by 589% from 1998 to 2013 (coefficient = 0.18; 95% CI, 0.15-0.22; p < 0.001). The proportion of AKAs resulting from dysvascular causes decreased (coefficient = 0.18; 95% CI, 0.15-0.22; p < 0.001), whereas that resulting from malignancy (coefficient = 0.04; 95% CI, 0.03-0.05; p < 0.001) and trauma (coefficient = 0.13; 95% CI, 0.09-0.18; p < 0.001) increased.

CONCLUSIONS

The incidence of AKAs has decreased in the United States. AKAs related to dysvascular disease and other etiologies such as trauma and malignancy have either substantially decreased or remained fairly constant, whereas that resulting from PJI more than tripled. Given the increased resource utilization associated with limb loss, the results of this study suggest that national efforts to reduce disability should prioritize PJI. Further studies are required to evaluate the risk factors for AKA from PJI and to formulate better strategies to manage PJI.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Surgical Space Suits Increase Particle and Microbiological Emission Rates in a Simulated Surgical Environment

BACKGROUND

The role of space suits in the prevention of orthopedic prosthetic joint infection remains unclear. Recent evidence suggests that space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause. This study aimed to compare the particle and microbiological emission rates (PER and MER) of space suits and standard surgical clothing.

METHODS

A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during 5 separate experiments. Particle counts were analyzed with 2 separate particle counters capable of detecting particles between 0.1 and 20 μm. An Andersen impactor was used to sample bacteria, with culture counts performed at 24 and 48 hours.

RESULTS

Four experiments consistently showed statistically significant increases in both PER and MER when space suits are used compared with standard surgical clothing. One experiment showed inconsistent results, with a trend toward increases in both PER and MER when space suits are used compared with standard surgical clothing.

CONCLUSION

Space suits cause increased PER and MER compared with standard surgical clothing. This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in clinical studies.

[Handling of retrieved implants in orthopedic surgery : Results of a survey within the framework of the EndoCert initiative]

BACKGROUND

Although investigations of retrieved medical implants can provide valuable information about the cause of the revision, there is a lack of information, which could be avoided by consequent failure analyses. In the framework of the EndoCert certification system it is obligatory to record and report incidents.

OBJECTIVES

The present work examines how the willingness to report has developed in certified arthroplasty centers and which method of handling retrievals is preferred and actually used.

MATERIALS AND METHODS

On the basis of a questionnaire for handling retrievals, all 508 arthroplasty centers that were certified till June 1, 2016, were included (return rate = 97.2%).

RESULTS

A total of 93.3% of the centers have established an algorithm for handling of retrievals and 83.0% of the centers prefer to hand out the retrieval to the patient, while only 25.7% wish to store it in the center for research purposes. In the case of a potential incident as the cause of revision, centers prefer to forward the retrieval to damage analysis, whereby the centers act in different ways, depending on the case. An implant fracture is, e.g., considered a reportable event in most cases without temporal limitation. On the other hand, breakage or failure of surgical instruments is considered not to be reported in the case of more than half of the centers. In 2014 and 2015, approximately 71% of EPZs reported no incidents.

CONCLUSIONS

According to our survey, many certified arthroplasty centers are sensitized to careful handling of retrievals. The treatment of the explanted components is conducted in different ways. The assessment of whether an incident is to be reported shows large differences. In view of the relatively high number of revision surgeries, the number of reports to the authorities appears to be low.

[Short-Term Results of the Carpometacarpal Joint Arthroplasty Using the Ivory® Prosthesis]

PURPOSE OF THE STUDY Trapeziometacarpal osteoarthritis affects primarily postmenopausal middle-aged and older women. Total joint replacement is one of the surgical treatment options for symptomatic advanced degenerative changes of the carpometacarpal joint. This study aims to evaluate the short-term functional and radiological results of the Ivory ® prosthesis with the minimum followup period of three years after the surgery. MATERIAL AND METHODS Presented are the results of 48 total trapeziometacarpal joint replacements in the group of 40 patients composed of 36 women and 4 men. The age of patients ranges from 41 to 75 years (median 56 years), with the ratio between the dominant and non-dominant upper extremity 23:25. The follow-up period ranged from 36 to 63 months (median 52 months). The surgery was indicated in patients with symptomatic trapeziometacarpal arthrosis of stage II, III and early stage IV according to Eaton-Glickel once the conservative therapy had failed. In all the patients, the evaluation of the function and pain of the operated joint by DASH score, the range of motion -thumb opposition by Kapandji score were carried out at regular intervals pre- and postoperatively, the radiological evaluation of the stage of degenerative joint condition was done preoperatively, whereas the position of the implant and the lengthening of the first column of the finger were assessed postoperatively. RESULTS Subjectively, the patients were satisfied with the result of the surgery. After the joint replacement, in 65% of cases the patients reported full satisfaction with no difficulties present, in 31% of cases the patients suffered from pain during loading, in 4% of cases the patients reported also occasional pain at rest. Postoperatively, the total DASH score values decreased from the mean preoperative value of 52.79 to 10.4 points at a three-year follow-up. The average value of pain dropped from 3.46 to 1.44 points 3 years after the surgery. The average range of motion - thumb opposition by Kapandji score increased from 8.57/10 to 9.85/10 one year after the surgery. The difference between the values of average increase in length of the first column of the finger was 0.14 mm in favour of the sub-group of symptomatic cases. In the evaluated group, the need for revision was determined in 4 implants. In 1case for aseptic loosening of the cup and three times for dislocation. After 36 months, 47 of 48 implants were in situ, the overall three-year survival was achieved in 97.9%. The most frequent postoperative complication was the occurrence of De Quervain s tenosynovitis (10%). DISCUSSION Currently, most of the newer types of modular uncemented hydroxyapatite-coated total "ball and socket" joint replacements present acceptable medium-term, and in some cases even long-term, results regarding the survival. The most pressing issue continues to be the survival of implants, particularly the failure of the trapezial component and the associated risk of revision surgery. Good postoperative results can be achieved by accurate indication, carefully applied cup implant and good postoperative cooperation of patients. The complementary study did not confirm that the lengthening of the thumb causes the postoperative development of De Quervain s tenosynovitis. CONCLUSIONS The uncemented first carpometacarpal joint total replacement using the Ivory ® prosthesis brings about very good shortterm functional and radiological results, with no occurrence of early aseptic loosening of the implant. Key words:rhizarthrosis, arthroplasty, carpometacarpal joint prosthesis, uncemented.

[Interposition and Suspension Arthroplasty of Carpometacarpal Joint of the Thumb Using the TIE-IN Implant]

PURPOSE OF THE STUDY The aim of the study was to present the surgical technique combining the interposition and suspension arthroplasty using the TIE-IN implant as a treatment option for advanced symptomatic to final stage rhizarthrosis. MATERIAL AND METHODS Since 2015 we have performed the interposition arthroplasty combined with suspension arthroplasty using the TIE-IN implant in 12 patients, mostly indicated for stage IV rhizarthrosis. In two cases stage III rhizarthrosis with concomitant trapezium destruction was present. In two other cases the patients suffered from secondary osteoarthrosis associated with rheumatoid arthritis. Pain under loads was present in all the patients, of whom in 10 patients also the pain at rest occurred. Preoperatively, a total of 10 patients showed subluxation of the first carpometacarpal joint of 50% of the articular surface width. The ratio between the dominant and non-dominant extremity was 1:1. As a part of the evaluation, correlation was established between the preoperative findings and the postoperative results at 3 months follow-up. The examination included the assessment of pain intensity by VAS scale, the range of motion measurement - by Kapandji thumb opposition test, handgrip strength test and functional evaluation using the scoring systems - DASH score, modified DASH score for thumb, and modified Wrightington score. RESULTS No intraoperative or postoperative complications such as infection, complex regional pain syndrome, implant failure or failed surgical procedure were reported in the given group of patients. The pain at rest ceased in all 12 patients. The VAS pain intensity score improved from the preoperative average of 5.8 to 0.8 postoperatively. The range of motion in all the patients with stage IV rhizarthrosis substantially improved. The average Kapandji thumb opposition score increased from 6.9 preoperatively to 9.5 postoperatively. DISCUSSION There are multiple surgical treatment options for advanced rhizarthrosis. Apart from the combination of interposition and suspension arthroplasty referred to above, it is trapeziometacarpal (TMC) arthrodesis on the one hand and carpometacarpal joint total arthroplasty on the other hand. The arthrodesis continues to be a fairly frequently used procedure, despite the final limitation of thumb movement. It is because of this loss of fine motor function why it is not the preferred technique for treating advanced rhizarthrosis at our department. On the very contrary, the total replacement of the TMC joint is at our department as well as at many other departments the treatment of choice for advanced symptomatic rhizarthrosis since in conservative resection of the articular surfaces the biomechanics of the carpometacarpal joint of the thumb is preserved. As an outcome, this technique combines the advantages of other surgical methods by ensuring full painless range of motion and strength of the joint as opposed to other techniques, which mostly result either in a limited movement, or in a loss of grip strength. There is a whole range of resection arthroplasty techniques available. From simple trapeziectomy, which leads to the radial column collapse and ultimately to a major functional deficit, up to various interposition or suspension arthroplasty techniques with the resulting range of motion, stability and thus grip strength depending on the technique applied. CONCLUSIONS By applying the combination of the interposition and suspension arthroplasty of the carpometacarpal joint of the thumb using the TIE-IN implant we preserve the length of the thumb, its stability, and thus achieve the recovery of adequate thumb range of motion and grip strength. Our conclusions are in correlation with the results obtained at reference centres. Key words:rhizarthrosis, trapeziometacarpal prosthesis, arthroplasty, trapezium implant.

Cervical disc arthroplasty with Prestige-LP for the treatment of contiguous 2-level cervical degenerative disc disease: 5-year follow-up results

The objective of this study is to present the long-term results and to evaluate the safety and effectiveness of the Prestige-LP cervical disc replacement in treatment of patients with symptomatic 2-level cervical degenerative disc disease.Twenty-four patients with 48 Prestige-LP disc were analyzed before surgery and at 1 week, 3 months, 6 months, 12 months, 24 months, and 60 months after surgery. Clinical assessments included 36-Short Form (SF-36), Japanese Orthopedic Assessment (JOA), visual analog scale (VAS), and Neck Disability Index (NDI) scores. Radiographic assessments included cervical lordosis (CL), disc height (DH), range of motion (ROM) of the total cervical spine, functional spinal unit (FSU) as well as upper and lower operated segment. Complications at the 5-year follow-up were collected as well.Mean follow-up period was 64.22 months. There was clinical improvement in terms of SF-36, JOA, NDI, and VAS from the preoperative to the final follow-up (P < .05). Overall, ROM of the total cervical spine, FSU, and upper and lower operated segment were maintained during the follow-up. Statistically significant (P < .05) improvements in the trend of CL and DH were noted at the follow-up. Eight patients were observed an appearance of heterotopic ossification at the 5-year follow-up, with 6 patients appeared at Class II and 2 patients at Class III. Adjacent segment degeneration assessed by radiographic evidence was found in 2 patients.Two-level cervical disc arthroplasty with Prestige-LP showed significant improvement in clinical outcomes at 5 years. It not only effectively preserves the motion of both total cervical spine and operated segments, but also restores normal CL and DH up to 5 years postoperation.

Failed Suture Button Suspensionplasty of the Thumb Carpometacarpal Joint Salvaged Using Pyrocarbon Arthroplasty

Carpometacarpal joint arthritis of the thumb is a common problem. Mini suture suspensionplasty has been reported as a successful treatment option. We describe a case of a ruptured suture button suspensionplasty that caused pain and thumb metacarpal subluxation. To our knowledge, this is the first reported mechanical failure of a suture suspensionplasty. Surgeons should be aware of this potential complication when using this device to treat thumb carpometacarpal arthritis surgically.

[Endoprosthesis Infections - Guidelines for Antibiotic Therapy Common Guidelines of the Czech Society for Orthopaedics and Traumatology and the Society for Infectious Diseases of the Czech Medical Association of J. E. Purkyně]

PURPOSE OF THE STUDY This study aims to articulate regional guidelines for curative and suppressive antibiotic therapy of total joint replacement infections. MATERIAL AND METHODS When developing the standard, used as source materials were the published foreign guidelines for antibiotic therapy of prosthetic joint infections, the analysis of resistance of bacterial strains conducted in the Hospital in České Budějovice, a.s. and the assessment of strain resistance for the Czech Republic published by the European Antimicrobial Resistance Surveillance Network (EARS-Net). Considered was also the availability of individual antibiotics in the Czech Republic and restricted prescription according to the Summary of Product Characteristics as specified in the State Institute for Drug Control marketing authorisation. The expert group composed of orthopaedists, microbiologists and infectious disease specialists elaborated the basic antibiotic guideline for choosing an appropriate antibiotic/antifungal drug based on the usual susceptibility, its dose and dosage interval for initial and continuation therapy. The comments of individual specialists were gradually incorporated therein and in case of doubts majority rule was applied. The drafted document was sent for peer reviews to clinical orthopaedic, infectious disease and microbiological centres, whose comments were also incorporated and the finalised document was submitted for evaluation to specialised medical societies. RESULTS The outcome is the submitted guideline for antibiotic curative and suppressive therapy suitable for managing the prosthetic joint infections, which was approved by the committee of the Czech Society for Orthopaedics and Traumatology andthe Society for Infectious Diseases of the Czech Medical Association of J. E. Purkyně. DISCUSION Curative therapy of total joint replacement infections consists primarily in surgical treatment and has to be accompanied by adequate antibiotic therapy administered initially intravenously and later orally over a sufficient period of time. Bearing in mind the wide spectrum of pathogens that can cause infections of a joint replacement and their capacity to form a biofilm on foreign materials, the correct choice of an antibiotic, its dose and dosage interval are essential for successful treatment. Such standard should respect regional availability of antibiotics, regional pathogen resistance/susceptibility and ensure the achievement of sufficiently high concentrations at the requested location including anti-biofilm activity. CONCLUSIONS The submitted guideline is not the only treatment option for joint total replacement infections, but it makes the decisionmaking easier when treating these complications in the form of infections. The final choice of an antibiotic, its dose and duration of therapy shall be based on a critical assessment of results of microbiological (blood culture and molecular genetic) tests and reflect the patient s clinical condition. Since these are multidisciplinary issues, we consider useful for this guideline to be commented upon and approved by the committee of both the Society for Orthopaedics and Infectious Diseases so that it can become the starting point for treatment. Key words: total joint replacement infection, TEP, ATB, antibiotic therapy, consensus meeting, guideline.

Total Wrist Arthroplasty

Total wrist arthroplasty (TWA), first performed in the late 19th Century, is still an infrequently used operation. It is most commonly indicated in patients with rheumatoid arthritis who have pan-carpal wrist involvement. It is an alternative to total wrist arthrodesis in patients who wish to preserve joint motion. Patients must lead a low-demand lifestyle and have failed non-operative measures. Complications are not insignificant and have been reported to be as high as 43%. Modern generation implants most often fail due to dislocation or loosening. Because wrist arthrodesis remains the gold standard treatment, particularly in patients with higher physical demands, it remains to be seen whether TWA will gain greater acceptance as prosthetic designs evolve.

Ion-Doped Silicate Bioceramic Coating of Ti-Based Implant

Titanium and its alloy are known as important load-bearing biomaterials. The major drawbacks of these metals are fibrous formation and low corrosion rate after implantation. The surface modification of biomedical implants through various methods such as plasma spray improves their osseointegration and clinical lifetime. Different materials have been already used as coatings on biomedical implant, including calcium phosphates and bioglass. However, these materials have been reported to have limited clinical success. The excellent bioactivity of calcium silicate (Ca-Si) has been also regarded as coating material. However, their high degradation rate and low mechanical strength limit their further coating application. Trace element modification of (Ca-Si) bioceramics is a promising method, which improves their mechanical strength and chemical stability. In this review, the potential of trace element-modified silicate coatings on better bone formation of titanium implant is investigated.

Development of superlattice CrN/NbN coatings for joint replacements deposited by high power impulse magnetron sputtering

The demand for reliable coating on medical implants is ever growing. In this research, enhanced performance of medical implants was achieved by a CrN/NbN coating, utilising nanoscale multilayer/superlattice structure. The advantages of the novel high power impulse magnetron sputtering technology, namely, its unique highly ionised plasma, were exploited to deposit dense and strongly adherent coatings on CoCr implants. Transmission electron microscopy analysis revealed coating superlattice structure with bi-layer thickness of 3.5 nm. CrN/NbN deposited on CoCr samples showed exceptionally high adhesion, critical load values of LC2 = 50 N in scratch adhesion tests. Nanoindentation tests showed high hardness of 34 GPa and Young's modulus of 447 GPa. Low coefficient of friction (μ) 0.49 and coating wear coefficient (K C) = 4.94 × 10(-16) m(3) N(-1) m(-1) were recorded in dry sliding tests. Metal ion release studies showed a reduction in Co, Cr and Mo release at physiological and elevated temperatures (70 °C) to almost undetectable levels (<1 ppb). Rotating beam fatigue testing showed a significant increase in fatigue strength from 349 ± 59 MPa (uncoated) to 539 ± 59 MPa (coated). In vitro biological testing has been performed in order to assess the safety of the coating in biological environment; cytotoxicity, genotoxicity and sensitisation testing have been performed, all showing no adverse effects.

Anatomic stemless shoulder arthroplasty and related outcomes: a systematic review

BACKGROUND

The latest generation of shoulder arthroplasty includes canal-sparing respectively stemless designs that have been developed to allow restoration of the glenohumeral center of rotation independently from the shaft, and to avoid stem-related complications. The stemless prosthesis design has also recently been introduced for use in reverse arthroplasty systems.

METHODS

We systematically reviewed the literature for studies of currently available canal-sparing respectively stemless shoulder arthroplasty systems. From the identified series, we recorded the indications, outcome measures, and humeral-sided complications.

RESULTS

We identified 11 studies of canal-sparing respectively stemless anatomic shoulder arthroplasty implants, published between 2010 and 2016. These studies included 929 cases, and had a mean follow-up of 26 months (range, 6 to 72 months). The rates of humeral component-related complications ranged between 0 and 7.9 %. The studies reported only a few isolated cases of complications of the humeral component. Some arthroplasty systems are associated with radiological changes, but without any clinical relevance.

CONCLUSIONS

All of the published studies of canal-sparing respectively stemless shoulder arthroplasty reported promising clinical and radiological outcomes in short to midterm follow-up. Long-term studies are needed to demonstrate the long-term value of these kind of implants.

Avanta Versus Swanson Silicone Implants in the MCP Joint—A Prospective, Randomized Comparison of 30 Patients Followed for 2 Years

The results of Swanson and Avanta metacarpophalangeal joint arthroplasties in rheumatoid patients were compared in a prospective, randomized study of 30 patients (120 implants). At 2-year follow-up, grip strength was measured, hand function was assessed with the Sollerman test and the subjective outcome was determined with visual analogue scores. With both implants ulnar deviation and flexion deformities decreased, and there was no difference between the groups. The increase in range of motion was 7° greater with Avanta implants than with Swanson implants. Grip strength and hand function were unaltered but the visual analogue scales showed decreased pain levels and subjective improvements in hand function, grip strength and cosmesis. Twenty-four of 30 patients were satisfied. Fracture of the silicone spacer occurred with 12 Avanta (20%) and eight Swanson implants (13%), with a higher fracture frequency in men.

A Comparative Study of Outcome between the Neuflex and Swanson Metacarpophalangeal Joint Replacements

This prospective double blind trial compares the clinical findings of Swanson and Neuflex metacarpophalangeal joint replacements in patients with rheumatoid arthritis, up to 2 years follow-up. There were 37 joints (10 patients) in the Swanson group and 40 joints (12 patients) in the Neuflex group. Assessments of range of movement, grip strength and hand function were undertaken in a double blind fashion, preoperatively and up to 2 years following implantation. The mean and standard deviation of the data were calculated. A two-tailed student’s t-test was used when comparing groups of data. An X-ray analysis was also undertaken to identify any implant failure.

There was no significant difference between the two groups with respect to flexion and extension before surgery. At follow-up there was also no significant difference in the extensor lag, with mean extension lags of 19° and 16° for the Swanson and Neuflex implants, respectively. However, there was a significant difference in flexion, with mean active flexion values of 59° and 72° for the Swanson and Neuflex implants, respectively. There were no differences between the two groups in respect to arc of metacarpophalangeal joint motion, ulnar deviation, grip strength or the SODA function test at follow-up. At this early stage there was no evidence of any case of implant failure.

In conclusion, patients who underwent Neuflex metacarpophalangeal joint replacements obtained greater flexion than those who underwent a Swanson replacement.

Long term results after bipolar radial head arthroplasty

Radial head fractures are common injuries, occurring mostly in active young people 85%. Treatment of the more complex radial head fractures (Mason type III and IV), appear to be challenging and remain a subject of controversy. Replacement of the radial head with a metal prosthesis imitates the stabilizing role of the radial head and has been considered as the treatment of choice. However, long-term results are scarce. We report our mid to long-term (mean 9.4 year) clinical and radiographic results after insertion of a Judet Bipolar Radial Head prosthesis. 34 patients were treated with the Judet Bipolar Head prosthesis between 2000 and 2008. In this study, 21 patients were re-examined after a mean period of 113 months (range, 174-84), ie, 9.4 years (range, 14.5-7). Follow-up examinations included both the Mayo Elbow Performance Index (MEPI) and Dis- abilities of the arm, shoulder and hand (DASH) score. Range of motion was measured with a hand goniometer. X-rays were evaluated for peri-articular ossifications, radiolucent lines and signs of proximal erosion, capitellar erosion. Mean Mayo Elbow Performance Index was 88.6 (Range 100-50). According to the MEPI score we had 14 excellent, 1 good, 5 fair results and one poor result. One patient reported severe pain, 3 patients reported moderate pain, one patient reported mild pain and 16 patients reported no pain at all. Difference between pronation-suppination range was noted between primary or secondary indication of the radial head, no other significant differences were found. Mean DASH score was 23.1° (Range 0-63) without difference between primary and secondary indication. Mean flexion was 121.8° (Range : 110-140), mean extension deficit was 24.8° (Range 15-40), mean pronation was 62.4° (Range : 50-80) and suppination 58.8° (Range : 45-80). Ten patients showed signs of ulnohumeral joint degenerative arthritis. One patient developed symptomatic ulna plus. One patient showed radiolucent lines surrounding the prosthesis with proximal bone erosion. There were no reports of dislocations of the prosthesis. One case of radiological signs of overlenghtening was noted. Mainly good clinical results are achieved with the -Judet bipolar radial head implant. Functional results after long term follow-up are, however less optimistic then the excellent results achieved after short- to mid-term follow-up. No clear link between radiological signs and functional results can be found.

Update on calcium pyrophosphate deposition

Calcium pyrophosphate crystal deposition (CPPD) associates with ageing, osteoarthritis (OA), uncommon metabolic diseases, mutations and polymorphisms in the ankylosis human gene (ANKH). CPPD is frequently polyarticular, occurs due to a generalised articular predisposition, and the association between CPPD and OA is joint specific, for example CPPD associates with knee OA, but not with hip OA. Other recently identified associations include knee malalignment (knee CC), low cortical BMD and soft-tissue calcification. CPPD is generally asymptomatic. A recent study reported that knees with OA plus CC at the index joint, or at distant joints (in absence of index joint CC), were more likely to have attrition. CPPD can cause acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and is frequently present in joints with OA. Joint aspiration remains the gold standard for diagnosing CPPD, although other promising techniques are emerging. Patients with polyarticular or young onset CPPD should be screened for underlying metabolic abnormalities, however, such testing can be unrewarding. The treatment of CPPD is symptomatic. Acute CPP crystal arthritis is treated with rest, local application of ice-packs, joint aspiration, colchicine and/or intra-articular corticosteroid injection (once infection is excluded). Colchicine, low-dose corticosteroids, hydroxychloroquine and radiosynovectomy are recommended for the treatment of chronic or recurrent acute CPP crystal arthritis. Recent RCTs did not confirm any benefit from methotrexate, and although there is increasing interest in the use of anti-IL1 agents for acute or chronic CPP crystal arthritis, their efficacy has not been formally examined. Unlike gout, currently there are no treatments to eliminate CPP crystal deposits.

Quantitative assessment and characterization of glenoid bone loss in a spectrum of patients with glenohumeral osteoarthritis

PURPOSE

Eccentric posterior bone loss and associated glenoid retroversion represent challenges to glenoid placement during total shoulder arthroplasty. This bone loss can lead to poor stability and perforation of the glenoid during arthroplasty. The purpose of this study was to evaluate the morphology of glenoid bone loss for a spectrum of osteoarthritis patients using 3D computed tomography imaging and simulation software.

METHODS

This study included 29 patients with glenohumeral osteoarthritis treated with shoulder arthroplasty. Three-dimensional reconstruction of preoperative CT images was performed. Glenoid bone loss was measured at ten, vertically equidistant axial planes along the glenoid surface at four distinct anterior-posterior points on each plane. The images were fitted with modeled pegged glenoid implants to predict glenoid perforation.

RESULTS

The 3D maps demonstrated greatest average bone loss posteriorly in the AP plane at the central axis of the glenoid in the SI plane. The average amount of bone loss was 3.85 mm. Walch A2 and B1 shoulders showed more central bone loss, while Walch B2 shoulders displayed more posterior and inferior bone loss. Patients with predicted peg perforation displayed significantly greater bone loss than those without predicted peg perforation (p = 0.037). Peg perforation was most common in Walch B2 shoulders occurring in the posterior direction involving the central and posterior-inferior peg.

CONCLUSIONS

These data demonstrate an anatomic pattern of glenoid bone loss for different classes of glenohumeral arthritis. These findings can be used to develop various models of glenoid bone loss to guide surgeons, predict failures, and develop better glenoid implants. This study has been approved by the Cleveland Clinic IRB: Number 6235.

The Etiology of Improved Outcomes at High Volume Centers Learning Theory and the Case of Implant Flashing

Increased volume has been shown to be associated with improved outcomes for many orthopaedic procedures. For individual surgeons, the concepts of learning curves and volume effects have been well established in the literature. For institutions, high-volume hospitals have also been shown to have better outcomes for orthopaedic procedures such as total joint replacements. However, exactly how hospital volume mediates this improvement is not well understood. Learning theory states that learning occurs as a result of accumulated experience, not based on time. We compared our institution's curve representing our implant flashing rates to other institutional data sets that exhibit learning and continuous quality improvement, including airline near misses, coal mining accidents, and others. Development of expertise is based on volume and rate of errors, and therefore higher volume is conducive to faster learning.

Does exchange arthroplasty of an infected shoulder prosthesis provide better eradication rate and better functional outcome, compared to a permanent spacer or resection arthroplasty? a systematic review

BACKGROUND

The best surgical modality for treating chronic periprosthetic shoulder infections has not been established, with a lack of randomised comparative studies. This systematic review compares the infection eradication rate and functional outcomes after single- or two-stage shoulder exchange arthroplasty, to permanent spacer implant or resection arthroplasty.

METHODS

Full-text papers and those with an abstract in English published from January 2000 to June 2014, identified through international databases, such as EMBASE and PubMed, were reviewed. Those reporting the success rate of infection eradication after a single-stage exchange, two-stage exchange, resection arthroplasty or permanent spacer implant, with a minimum follow-up of 6 months and sample size of 5 patients were included.

RESULTS

Eight original articles reporting the results after resection arthroplasty (n = 83), 6 on single-stage exchange (n = 75), 13 on two-stage exchange (n = 142) and 8 papers on permanent spacer (n = 68) were included. The average infection eradication rate was 86.7 % at a mean follow-up of 39.8 months (SD 20.8) after resection arthroplasty, 94.7 % at 46.8 months (SD 17.6) after a single-stage exchange, 90.8 % at 37.9 months (SD 12.8) after two-stage exchange, and 95.6 % at 31.0 months (SD 9.8) following a permanent spacer implant. The difference was not statistically significant (p = 0.650). Regarding functional outcome, patients treated with single-stage exchange had statistically significant better postoperative Constant scores (mean 51, SD 13) than patients undergoing a two-stage exchange (mean 44, SD 9), resection arthroplasty (mean 32, SD 7) or a permanent spacer implant (mean 31, SD 9) (p = 0.029). However, when considering studies comparing pre- and post-operative Constant scores, the difference was not statistically significant.

CONCLUSION

This systematic review failed to demonstrate a clear difference in infection eradication and functional improvement between all four treatment modalities for established periprosthetic shoulder infection. The relatively low number of patients and the methodological limitations of the studies available point out the need for well designed multi-center trials to further assess the best treatment option of peri-prosthetic shoulder infection.

Scapular Notching

Developed in 1985, the Grammont-style reverse total shoulder arthroplasty offered a biomechanical advantage for the deltoid muscle as well as predictably reduced pain and improved shoulder function in rotator cuff-deficient shoulders. Despite favorable outcomes, reverse total shoulder arthroplasty is associated with a unique set of complications, one of which is scapular notching. Scapular notching is believed to be a result of mechanical impingement of the humeral component on the lateral scapular pillar. Although it appears that scapular notching progresses with time, its effect on implant survivorship and clinical outcomes is unknown. Factors associated with scapular notching are categorized into several groups, including patient-specific risk factors, surgical approach and technique, and prosthetic design. Surgical strategies to reduce the rate of scapular notching include inferior positioning of the glenosphere, inferior tilting of the glenosphere, and increasing the size of the glenosphere. A lateralized center of rotation and a decreased humeral shaft-neck angle also decrease the incidence of scapular notching. As the indications for reverse total shoulder arthroplasty expand, it is important for orthopaedic surgeons to understand the etiology and incidence, predictive factors, and clinical relevance of scapular notching as well as strategies to avoid it.

Biomechanics of Reverse Shoulder Arthroplasty: Current Concepts

The evolution of reverse shoulder arthroplasty has provided surgeons with new solutions for many complex shoulder problems. A primary goal of orthopaedics is the restoration or re-creation of functional anatomy to reduce pain and improve function, which can be accomplished by either repairing injured structures or replacing them as anatomically as possible. If reconstructible tissue is lacking or not available, which is seen in patients who have complex shoulder conditions such as an irreparable rotator cuff-deficient shoulder, cuff tear arthropathy, or severe glenoid bone loss, substantial problems may arise. Historically, hemiarthroplasty or glenoid grafting with total shoulder arthroplasty yielded inconsistent and unsatisfactory results. Underlying pathologies in patients who have an irreparable rotator cuff-deficient shoulder, cuff tear arthropathy, or severe glenoid bone loss can considerably alter the mechanical function of the shoulder and create treatment dilemmas that are difficult to overcome. A better biomechanical understanding of these pathologic adaptations has improved treatment options. In the past three decades, reverse total shoulder arthroplasty was developed to treat these complex shoulder conditions not by specifically re-creating the anatomy but by using the remaining functional tissue to improve shoulder balance. Reverse total shoulder arthroplasty has achieved reliable improvements in both pain and function. Initial implant designs lacked scientific evidence to support the design rationale, and many implants failed because surgeons did not completely understand the forces involved or the pathology being treated. Implant function and clinical results will continue to improve as surgeons' biomechanical understanding of shoulder disease and reverse shoulder arthroplasty implants increases.

Reverse Shoulder Arthroplasty for Trauma: When, Where, and How

Reverse shoulder arthroplasty has become increasingly popular for the treatment of complex shoulder injuries, including proximal humerus fractures and fixed glenohumeral dislocation, in the elderly population. The early to midterm results of reverse shoulder arthroplasty for the treatment of proximal humerus fractures are promising compared with the results of unconstrained humeral head replacement, and patients may have more predictable improvement with less dependence on bone healing and rehabilitation. However, long-term follow-up is needed, and surgeons must be familiar with various complications that are specific to reverse shoulder arthroplasty. To achieve optimal patient outcomes for the management of traumatic shoulder injuries, surgeons must have a comprehensive understanding of the current implant options, indications, and surgical techniques for reverse shoulder arthroplasty.

Emerging Indications for Reverse Shoulder Arthroplasty

Historically, reverse shoulder arthroplasty was reserved for older, low-demand patients in whom rotator cuff arthropathy was diagnosed. Other common indications included sequelae of previously treated proximal humerus fractures, failed anatomic total shoulder arthroplasty, tumor resection, and rheumatoid arthritis in the elderly population. Unpredictable implant durability and high complication rates have limited the use of reverse shoulder arthroplasty to a narrow group of patients. Over the past decade, however, research has led to an improved understanding of the biomechanics behind reverse shoulder prostheses, which has improved implant design and surgical techniques. Consequently, orthopaedic surgeons have slowly begun to expand the indications for reverse shoulder arthroplasty to include a wider spectrum of shoulder pathologies. Recent studies have shown promising results for patients who undergo reverse shoulder arthroplasty for the treatment of acute proximal humerus fractures, massive rotator cuff tears without arthropathy, primary osteoarthritis, and chronic anterior dislocation, as well as for younger patients who have rheumatoid arthritis. These data suggest that, with judicious patient selection, reverse shoulder arthroplasty can be an excellent treatment option for a growing patient cohort.

Shoulder Arthroplasty: Key Steps to Improve Outcomes and Minimize Complications

Advances in shoulder replacement surgery have allowed for the successful treatment of various shoulder conditions. As the elderly population increases and the surgical indications for shoulder replacement surgery continue to expand, the number of shoulder replacements performed annually will continue to increase. Accordingly, the number of complications also will be expected to increase. Successful shoulder replacement outcomes require surgeons to have a thorough understanding of the surgical indications, surgical technique, and potential complications of the procedure. By reviewing the key aspects of shoulder replacement surgery and focusing on the surgical technique and common complications for both anatomic and reverse total shoulder arthroplasty, surgeons can help improve outcomes and minimize complications.

[Alloplastic Materials and their Propensity to Bacterial Colonisation]

PURPOSE OF THE STUDY The alloplastic materials currently used for protective surface layers on implants were tested in vitro under microbiological laboratory conditions by contamination with microbial agents most frequently found in deep infection of total joint replacements. The objective was to find out how the resistance to bacterial colonisation was related to different surface finishes. MATERIAL AND METHODS Each of 14 samples of alloplastic material currently used in the manufacture of orthopaedic implants was inoculated with each of the group of microorganisms most frequently infecting joint replacements; these were Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli. At 24 hours of incubation, biofilms produced on sample surfaces were collected, stained with crystalline violet and assessed by spectrophotometry. The average value of biofilm absorbances (AV595) for the group of microorganism tested was taken as a basic characteristic of each material sample indicating its sensitivity to bacterial. RESULTS Of the metal materials with smooth surface finish, Vitalium (AV595, 0.368) showed the lowest affinity to microbial colonisation; next was titanium (AV595, 0.459) and steel (AV595, 0.505). A significant increase in sensitivity to bacterial colonisation was recorded in all types of surface finish of steel (AV595, 0.571) and in titanium alloy with a rough surface texture (AV595, 0.737 to 1.676); p < 0.05. Porous titanium surfaces significantly increased material affinity to colonisation. DISCUSSION Our study had certain limitations concerning in vitro evaluation of porous surfaces that have high affinity to bacterial colonisation. Porous titanium, and its hydroxyapatite layer in particular, considerably promotes osteoblast colonisation of the surface as well as implant osseointegration in the bone bed. Microorganisms therefore have no room for surface colonisation. Problematic may remain the surface parts outside contact with bone that keep their affinity to bacterial colonisation. CONCLUSIONS The material of choice for cemented implants is Vitalium which, of all metal surfaces, has the lowest sensitivity to bacterial colonisation. The materials of choice for cementless implants are titanium alloys. However, an osteoactive surface not in contact with bone remains a problem. On the one hand, its roughness and porosity are crucial to good osseointegration, on the other hand, its affinity to bacterial colonisation is high.

KEY WORDS

alloplastic material, biofilm, joint replacement infection.

Correlation Between Clinical Outcomes and Anatomic Reconstruction with Anatomic Total Shoulder Arthroplasty

Many glenohumeral studies have demonstrated how anatomy varies across the population. Third and fourth generation shoulder prosthesis designs were developed to provide greater modularity and size ranges to better reproduce this anatomy and thus achieve better results in terms of shoulder function. This study quantifies the quality of anatomic reconstruction and compares that to long-term clinical outcomes using one fourth generation platform shoulder system.

METHODOLOGY

One hundred and forty primary total shoulder arthroplasties were performed by one experienced single surgeon between 2001 and 2009, using the same fourth generation modular prosthesis. Pre- and postoperative clinical assessments were quantified with the Constant, ASES, SPADI, SST, and UCLA scores, and active range of motion was measured. Five anatomic parameters were defined, measured, and compared pre- and postoperatively on the anterior-posterior (AP) radiographs: Humeral Head Height (HHH), Humeral Head Centering (HHC), Humeral Head Medial Offset (HHMO), Humeral Head Diameter (HHD), and Humeral Neck Angle (HNA). The differences between each of the parameters were then calculated and rated from 0 to 2 and then summed for each patient to obtain the Anatomic Reconstruction Index (ARI), which objectively quantifies and assesses the quality of the anatomic reconstruction. Patients were sorted based upon their ARI score into two groups (ARI 5 to 7 and ARI 8 to 10), and their latest follow-up outcomes were compared using the Mann-Whitney test to identify differences in preoperative and postoperative results, where p < 0.05 denoted a significant difference.

RESULTS

Of the 140 primary prostheses performed, 78 patients were lost to follow-up, and 13 were excluded for complications that were not related to the anatomic reconstruction. Forty-nine patients (75.8 yrs., 31F/18M) were included with an average follow-up of 9.1 years. The average score for HHH was 1.9 ± 0.4, 1.8 ± 0.5 for HHC, 1.7 ± 0.5 for HHMO, 1.7 ± 0.5 for HHD, and 1.5 ± 0.7 for HNA. Thus, all reconstructions were rated good to excellent with 86% of very good/excellent reconstruction (ARI 8 to 10) and 14% good reconstruction (ARI 5 to 7). A comparison of radiographic anatomic parameters was performed for these two cohorts: HHC (< 0.0001), HNA (0.000), and ARI (<0.0001) were significantly greater for the ARI 8 to 10 cohort. Four of five postoperative clinical outcome metrics for the ARI 8 to 10 cohort were significantly greater than the mean values for the ARI 5 to 7 cohort. Additionally, mean postoperative pain on a daily basis and shoulder function for the ARI 8 to 10 cohort were significantly greater than that for the ARI 5 to 7 cohort.

DISCUSSION

The relatively small number of good reconstructions (14%) compared to very good/excellent reconstructions (86%) and the absence of fair/poor reconstructions limited the ability for any strong linear correlations between anatomical reconstruction and clinical parameters. Despite this, patients with larger mean ARI scores were associated with significantly better outcomes for some measures. This study is limited by the use of 2D assessments from standard AP radiographs; this method can be further refined by the use of 3D quantitative assessment of each parameter.

CONCLUSION

This study confirmed that an improved anatomic reconstruction results in better postoperative clinica outcomes. The fourth generation prosthesis used for this study allows continuous in-situ adjustment of the humeral head orientation through use of the spherical taper on the replicator plate and also a double adjustment of offset through the use of the offset humeral head and offset taper on the replicator plate.

A Comparison and Correlation of Clinical Outcome Metrics in Anatomic and Reverse Total Shoulder Arthroplasty

INTRODUCTION

Indications for anatomic (aTSA) and reverse (rTSA) total shoulder arthroplasty are well defined and dependent on the function of the rotator cuff; however, indications for rTSA have gradually extended to complex fractures, revisions, and primary arthritis in very elderly patients. The risk of secondary rupture of a weakened or degenerative rotator cuff is difficult to assess and can lead the orthopaedic surgeon to hesitate between aTSA or rTSA. It, therefore, seems appropriate to compare these two types of prostheses in terms of pain, functional, clinical outcome metric scores, and complications, despite suspected differences between populations and the respective diseases.

METHODOLOGY

1,145 patients (69.2 ± 8.9 years) were treated by 12 orthopaedic surgeons in France and in the USA, using either aTSA or rTSA with one platform shoulder system. Five hundred twenty-eight patients received aTSA (66.2 ± 9.0 years; 283 female, 245 male) for treatment of degenerative arthritis, and 617 patients received rTSA (71.8 ± 8.0 years; 392 female, 225 male) for treatment of cuff tear arthroplasty, rotator cuff tear, and osteoarthritis. Each patient was scored preoperatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI metrics; active range of motion was also measured. The average follow-up for all patients was 39.7 ± 18.7 months (aTSA: 42.7 ± 21.9 months; rTSA: 37.1 ± 15.1 months). Improvements in outcome using each metric score were normalized on a 100 point scale, correlated, and compared. A Student's two-tailed, unpaired t-test was used to identify differences in preoperative, postoperative, and pre-to-postoperative improvements, where p < 0.05 denoted a significant difference.

RESULTS

Preoperatively, rTSA patients had significantly lower mean outcome scores and significantly lower mean active range of motion as compared to aTSA patients. Post-operatively, rTSA and aTSA patients showed no significant difference in active forward flexion or in mean outcome scores as measured by four of the five metrics. rTSA patients had significantly lower active abduction, internal rotation, and active and passive external rotation than aTSA patients. However, they had significantly better strength (9.7 vs. 7.3 lbs, p < 0.0001). Preoperative to postoperative mean improvements were compared between both cohorts. rTSA patients were associated with significantly larger improvements in outcomes and also had significantly better improvements in active forward flexion and strength. Conversely, aTSA patients had significantly better improvement in active and passive external rotation and active internal rotation. Analysis of complications demonstrated a very similar rate between cohorts, with aTSA patients associated with a slightly lower rate (6.6 vs. 7.3%).

CONCLUSION

This retrospective analysis of prospectively acquired data from 1,145 patients who received either a primary aTSA or rTSA prosthesis demonstrates that each device provides significant improvements with very similar mean results. In fact, the mean clinical outcomes associated with the reverse shoulder prostheses approach that of the "gold standard" anatomic device for their respective indications. Furthermore, the complication rates in this series are very similar and also favorable relative to the clinical literature. Findings, such as these, may at some point extend the indications of the reverse prosthesis to patients for whom an anatomical prosthesis could lead to a premature deterioration of the result.

Role of Subscapularis Repair on Muscle Force Requirements with Reverse Shoulder Arthroplasty

Concomitant repair of the subscapularis with reverse shoulder arthroplasty (rTSA) is controversial. To evaluate the biomechanical impact of subscapularis repair with rTSA, a cadaveric shoulder controller quantified the muscle forces required to elevate the arm during scapular abduction with the elbow flexed at 90°. The results of this study demonstrate that concomitant subscapularis repair with rTSA creates a biomechanically unfavorable condition during arm elevation. Specifically, repair of the subscapularis significantly increased the force required by the deltoid and posterior rotator cuff and also significantly increased the joint reaction force relative to when the subscapularis was not repaired. These results also demonstrated that both the 42 mm Grammont and 42 mm Equinoxe® rTSA prostheses significantly decreased the mean force required by the posterior rotator cuff and also significantly decreased the mean joint reaction force over the range of motion relative to the native joint with a rotator cuff tear (supraspinatus). As the posterior rotator cuff is often compromised in patients undergoing rTSA, patients may not be able to sustain these elevated forces in the infraspinatus and teres minor required to counteract the adduction and internal rotation moments generated by the subscapularis during activities of daily living. Similarly, the elevated posterior deltoid force and joint reaction loads could be deleterious to the long-term life of the prosthesis and can also increase the risk of loosening and fractures. For all these reasons, rTSA functional outcomes may be compromised if the subscapularis is repaired.

Optimization of Cemented Glenoid Peg Geometry. A Comparison of Resistance to Axial Distraction

INTRODUCTION

Glenoid loosening is one of the most common complications of anatomic total shoulder arthroplasty (aTSA). Numerous glenoid pegged designs exist within the market place; however, little effort has been made to optimize peg geometry, and as a result, there is no consensus regarding the superiority of one design over another. The aim of this study was to determine the impact of peg design on the fixation strength by comparing the force and displacement associated with five different geometries of cemented glenoid components when each is axially displaced from two different densities of polyurethane bone substitute substrates.

METHODS

An axial pull-out test was conducted on five different cemented peg geometries in both low- and high- density polyurethane bone-substitute blocks. All substrates were prepared utilizing a drill, which created a 7.3 mm diameter hole to a depth of 26.8 mm. Cemex ® brand bone cement was prepared and used to cement all pegs. After cementation of each peg, an electromechanical load frame applied a linear ramp displacement of 10 mm/minute axially to each peg while the polyurethane block was fully con strained. Load and displacement of each peg was sampled at 100 Hz until failure and axial distraction of each peg where the peak pull-out force and associated displacement were recorded. The average load to failure and associated displacement for each peg geometry were compared utilizing the Student's t-test where a p-value < 0.05 determined significance.

RESULTS

Cemented peg design #3 was associated with the greatest axial load to failure (675.3 N ± 18.8 N in low density and 707.3 N ± 11.7 N in high density) for both densities of bone-substitute blocks. Peg designs #5 and #2 were associated with the next highest axial loads to failure in both low and high density blocks. Finally, peg designs #1 and #4 were associated with the lowest axial loads to failure in both low and high density blocks. Only design #3 had a statistically significant difference between peak pull-out forces between the low- and high-density bone substitute blocks, as compared to all other designs.

CONCLUSIONS

The results of this study demonstrate that glenoid peg geometry can significantly influence the resistance to axial distraction where the continuous threaded geometry exemplified by peg design #3 demonstrated significantly superior cemented fixation relative to the other peg designs. It can be concluded that overall macrostructure and design of the peg itself plays a key role in pull-out force; however, performance in a clinical setting is required to confirm these biomechanical results.

Analysis of Glenoid Fixation with Anatomic Total Shoulder Arthroplasty in an Extreme Cyclic Loading Scenario

INTRODUCTION

ASTM F2028-14 was adopted to recom mend a cyclic eccentric glenoid edge loading test that simulates the rocking horse loading mechanism beleived to cause aTSA glenoid loosening. While this method accurately simulates that failure mechanism, the recommended 750 N load may not be sufficient to simulate worst-case loading magnitudes, and the recommended 100,000 cycles may not be sufficient to simulate device fatigue-related failure modes. Finally, if greater loading magnitude or a larger number of cycles is performed, the recommended substrate density may not be sufficiently strong to support the elevated loads and cycles. To this end, a new test method is proposed to supplement ASTM F2028-14.

METHODS

A series of cyclic tests were performed to evaluate the long-term fixation strength of two different hybrid glenoid designs in both low (15 pcf) and high (30 pcf) density polyurethane blocks at elevated loads relative to ASTM F2028-14. To simulate a worst case clinical condition in which the humeral head is superiorly migrated, a cyclic load was applied to the superior glenoid rim to induce a maximum torque on the fixation pegs for three different cyclic loading tests: 1. 1,250 N load for 0.75 M cycles in a 15 pcf block, 2. 1,250 N load for 1.5 M cycles in a 30 pcf block, and 3. 2,000 N load for 0.65 M cycles in a 30 pcf block.

RESULTS

All devices completed cyclic loading without failure, fracture, or loss of fixation regardless of glenoid design, polyurethane density, loading magnitude, or cycle length. No significant difference in post-cyclic displacement was noted between designs in any of the three tests. Post-cyclic radiographs demonstrated that each device maintained fixa - tion with the metal pegs within the bone-substitute blocks with no fatigue related failures.

DISCUSSION

These results demonstrate that both cemented hybrid glenoids maintained fixation when tested according to each cyclic loading scenario, with no difference in post-cyclic displacement observed between designs. The lack of fatigue-related failures in these elevated load and high cycle test scenarios are promising, as are the relatively low displacements given the extreme nature of each test. This cyclic loading method is intended to supplement the ASTM F2028-14 standard that adequately simulates the rocking horse loading mechanism but may not adequately simulate the fatigue-related failure modes.

Impact of Posterior Wear on Muscle Length with Reverse Shoulder Arthroplasty

The use of reverse total shoulder arthroplasty (rTSA) in patients with posterior glenoid wear can be challenging. Implanting a baseplate in the correct version may require significant eccentric reaming, which further medializes the joint line and results in greater rotator cuff muscle shortening. To restore the joint line, bone graft may be required, though it is associated with additional risks. As an alternative solution, augmented glenoid baseplates offer the potential to restore the joint line and improve rotator cuff muscle tensioning without the need for eccentric reaming or supplemental bone graft. To that end, this computer analysis quantifies the rotator cuff muscle length for standard and augmented rTSA when used in a normal and posteriorly worn glenoid. These results demonstrate that shortening of the rotator cuff occurred for both the standard and posterior augmented reverse shoulder designs with additional muscle shortening occurring in scapula with posteriorly worn glenoids. More anatomic rotator cuff muscle tensioning was observed with augmented glenoid baseplates. The use of posterior augmented glenoid baseplates has the potential to improve stability and better restore active internal and external rotation, a current limitation of rTSA. However, clinical follow-up is necessary to confirm these favorable biomechanical results.

Rate of Improvement in Clinical Outcomes with Anatomic and Reverse Total Shoulder Arthroplasty

INTRODUCTION

The rate of clinical improvement has never been studied after anatomic (aTSA) and reverse (rTSA) total shoulder arthroplasty. This study quantifies the rate of improvement after aTSA and rTSA using five different scoring metrics for 1,641 patients.

METHODS

We evaluated 1,641 (69 ± 9.3 years old) patients treated by 14 orthopaedic surgeons using either aTSA or rTSA with a single platform shoulder system. Seven hundred twenty-nine patients received aTSA, and 912 patients received rTSA. Each patient was scored preoperatively and at various follow-up intervals (2 weeks, 6 weeks, 3 months, 6 months, annually, etc.) with a maximum follow-up time of 139 months using the SST, UCLA, ASES, Constant, and SPADI metrics. In addition, range of motion was measured. The rate of improvement was analyzed using a 40-point moving filter treadline over the entire range of follow-up.

RESULTS

All metrics improved in a majority of patients with less than 5% worsening after 6 months. While gains in motion were present in the majority of patients after aTSA, a higher incidence of patients failed to experience improvement in range of motion after rTSA. Clinical worsening was seen in up to 10% and 20% of the visits for active flexion and abduction and external rotation, respectively. The majority of clinical improvement after aTSA and rTSA was noted in the first 6 months with full improvement noted by 12 to 24 months. During the first 12 months, the rate of improvement associated with rTSA patients was generally 30% larger than that of aTSA patients.

DISCUSSION

The results of this large-scale database analysis demonstrate the reliability of improvements in outcomes and motion achieved with both aTSA and rTSA for various indications. For both aTSA and rTSA, less than 5% of patients reported worsening in each of the five clinical metrics after 6 months postoperative follow-up time. This study is significant because it quantifies how patient outcomes improve with time following treatment with both aTSA and rTSA. These results can be used to establish realistic patient expectations regarding the typical follow-up time required for pain to be reduced and function restored following surgical treatment with a total shoulder prosthesis.

Bone Grafting the Glenoid Versus Use of Augmented Glenoid Baseplates with Reverse Shoulder Arthroplasty

BACKGROUND

Large glenoid defects are a difficult reconstructive problem for surgeons performing reverse shoulder arthroplasty (rTSA). Options to address glenoid defects include eccentric reaming, bone grafting, and augmented glenoid baseplates. Augmented glenoid baseplates may provide a simpler, cost-effective, bone-preserving option compared to other techniques. No studies report the use of augmented baseplates to correct glenoid deformity in rTSA relative to the use of glenoid bone graft.

MATERIALS AND METHODS

We retrospectively reviewed 80 patients that received a primary rTSA and received either a structural bone graft or an augmented glenoid baseplate to address a significant glenoid defect. There were 39 patients in the augmented baseplate cohort and 41 patients in the bone graft cohort. The augmented baseplate cohort contained 24 8° posterior augment implants and 15 10° superior augment baseplates. The bone graft cohort consisted of 36 autograft humeral heads and 5 allograft femoral heads. The average follow-up for rTSA patients with an augmented baseplate was 28.3 ± 5.7 months, and the average follow-up for rTSA patients with glenoid bone graft was 34.1 ± 15.0 months. Each patient was scored preoperatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI metrics. Range of motion data was obtained as well.

RESULTS

All patients demonstrated significant improvements in pain, ROM, and functional scores following treatment with rTSA using either augmented baseplates or glenoid bone graft to correct glenoid defects. The database contained no complications for the augmented glenoid baseplate cohort, and six complications (14.6%) for the glenoid bone graft cohort (including two glenoid loosenings and graft failures). Additionally, the augmented baseplate cohort showed a lower scapular notching rate of 10% as compared to the bone graft cohort which had a notching rate of 18.5%.

DISCUSSION

The results of this study suggest that either augmented glenoid baseplates or glenoid bone graft can be used to address large glenoid defects during rTSA with significant improvement in outcomes. Augmented glenoid baseplates may achieve a lower complication and scapular notching rate, but additional and longer-term clinical follow-up is required to confirm these results.

Assessment of the Anatomic Neck as an Accurate Landmark for Humeral Head Resurfacing Implant Height Placement

INTRODUCTION

Humeral head resurfacing has been described as a more anatomic replacement alternative for proximal humerus arthroplasties when compared to conventional stemmed implants. However, not all studies show that humeral head resurfacing is better at reproducing the proximal humeral anatomy with overstuffing of the joint being a common complication. The purpose of this study was to assess the use of the anatomic neck as a landmark for proper placement of humeral head replacements.

METHODS

Sixty-six cadaveric shoulder CT scans were reconstructed using Mimics to create 3D models of the humerus. After 3D reconstruction, each bone model was analyzed in Rapidform to establish the anatomic neck plane, the humeral head average radius of curvature, and anatomic center of rotation (CoR) using a best fit sphere over the articular surface. Humeral head resurfacing implants (Equinoxe®, Exactech, Inc.) were assembled onto the 3D humeral models, selected by matching the closest implant size available with the anatomic radius of curvature. Implants were constrained to match the anatomic neck angle and version and were spaced 2 mm away from the anatomic neck. The 3D distances between the anatomic center of rotation and the implant CoR and the implanted head thickness deviations were measured using Unigraphics to observe anatomic reproduction with the resurfacing implants.

RESULTS

When placing all resurfacing implants 2 mm from the anatomic neck, the average implant CoR offset from the anatomic CoR was determined to be 1.03 mm ± 0.75 mm. The average implant Humeral Head Thickness (HHT) deviation from the anatomic HHT was determined to be -0.36 mm ± 0.84 mm. There were no significant differences in CoR offset or HHT offset between implant sizes used.

DISCUSSION

Newer generation resurfacing implant designs allow for more anatomic reproduction of the humeral articular surface. Depth of reaming and resurfacing implant height placement are potential pitfalls in humeral head replacement and have been shown to have negative effects on reproducing the CoR and HHT. Using the anatomic neck as a landmark for the depth of reaming has been observed to closely reproduce anatomic HHT and CoR. Further work aims to validate the use of the anatomic neck as a consistent landmark in cadaveric studies and to investigate if these findings are clinically relevant.

Preliminary Results of a Novel Hybrid Cage Glenoid Compared to an All-Polyethylene Glenoid in Total Shoulder Arthroplasty

INTRODUCTION

The aim of this study was to evaluate the preliminary outcomes of a hybrid cage glenoid design in comparison to pegged all-polyethylene glenoid components in anatomic total shoulder arthroplasty (aTSA).

MATERIALS AND METHODS

Ninety-two patients undergoing primary anatomic total shoulder arthroplasty with minimum two-year follow-up were reviewed. Forty-six patients had an ultra-high molecular weight polyethylene (UHMWPE) cemented pegged glenoid component, and 46 had a hybrid cage glenoid component. Patient data was retrospectively reviewed from prospectively acquired data in a multi-institutional IRB approved database. These age, gender, and follow-up matched patients were evaluated and scored preoperatively and a latest follow-up using the SST, UCLA, ASES, Constant, and SPADI scoring metrics. Additional measures included active abduction, elevation, and external rotation. Radiolucent line assessment of the glenoid was performed by use of a Grashey and axillary radiograph at latest follow-up. A Student's two tailed, unpaired t-test was used to identify differences in preoperative and postoperative results, where p < 0.05 denoted a significant difference.

RESULTS

All patients demonstrated significant improvements in pain and function following treatment with the primary aTSA. The database contained three complications for the aTSA patients with a cage glenoid, and three complications for patients with a UHMWPE pegged glenoid. Radiographic data was available for 37 of 46 cage glenoid patients and 29 of 46 UHMWPE pegged glenoid patients. Five of 37 cage glenoid patients had a radiolucent line (13.5%) with an average radiographic line score of 0.22. Eight of 29 UHMWPE peg glenoid patients had a radiolucent line (27.6%) with an average radiographic line score of 0.57. Cage aTSA patients were associated with significantly less blood loss than aTSA UHMWPE pegged glenoid patients (avg. blood loss = 242 vs. 337; p = 0.022).

CONCLUSION

At minimum two-year follow-up, hybrid cage aTSA components show equal clinical outcomes to UHMWPE pegged glenoids. However, the hybrid cage components had significantly fewer radiolucent lines and less intra-operative blood loss. Additional and longer-term clinical and radiographic follow-up is necessary to confirm these promising early results.

Subscapularis Preserving Technique in Anatomic Total Shoulder Arthroplasty. The Superior and Inferior Approach

Subscapularis tenotomy for anatomic total shoulder arthroplasty has been the standard approach for shoulder surgeons that use the deltopectoral approach. The risk of subscapularis insufficiency after this approach has been well documented. In order to avoid subscapularis complications, subscapularis sparing approaches through the rotator interval have been developed. We present two alternative subscapularis preserving techniques that are performed through the deltopectoral interval and allow more complete osteophyte excision and accurate humeral head sizing. These techniques require modified instrumentation and are facilitated by the use of an adaptable prosthesis with dual eccentricity. Future studies will examine the comparative clinical and radiographic outcomes of these techniques.

Improving Distal Fixation with Total Shoulder Arthroplasty in Cases of Severe Humeral Bone Loss

The usage of and indications for total shoulder arthroplasty have grown in recent years. Certain aspects of these arthroplasty procedures can be very complex, especially in revision and fracture cases, often leading to proximal humerus bone loss. For cases with significant bone loss, there is a need for improved devices with additional options to treat a wider range of deformities while also mitigating existing complications and rates, such as poor distal fixation, inadequate soft tissue reattachment options, and joint instability. To that end, a fatigue and torsional test was conducted on two different devices to assess the ability of each to survive an extreme fatigue and torsional load when assembled in worst-case configurations. Evaluation of the Equinoxe® humeral reconstruction prosthesis demonstrated superior fixation in both the fatigue loading scenario and also the torsional loading scenario as compared to the 8 mm x 215 mm cemented humeral long stem, where each had only 80 mm of cemented fixation. The results of the fatigue test demonstrated that despite the humeral reconstruction prosthesis being subjected to a 960 N force and 45 Nm bending moment (which was significantly more challenging than the 576 N force and 24.2 Nm bending moment subjected to the cemented humeral long stem), the humeral reconstruction prosthesis completed 1 M cycles without fracture or failure. Additionally, the Equinoxe® humeral reconstruction prosthesis was associated with a significantly greater torsional resistance in both the torque to initial slip (29.4 Nm versus 8.2 Nm; p = 0.0002) and also the maximum torque to failure (44.3 Nm versus 12.1 Nm; p < 0.0001). These significant improvements in fixation are at least partially attributed to the application of a novel distal fixation ring, which is press fit around the diaphysis of the humerus to supplement the cemented fixation of the distal stem. These fatigue and torsional test results paired with several novel features of fer the potential for the Equinoxe® humeral reconstruction prosthesis to be an improved treatment option for patients with proximal humeral bone loss, though clinical follow-up is necessary to confirm these positive biomechanical results.

Preliminary Results of a Posterior Augmented Glenoid Compared to an all Polyethylene Standard Glenoid in Anatomic Total Shoulder Arthroplasty

INTRODUCTION

Osteoarthritis of the shoulder often results in significant posterior glenoid wear. The options for treating this have been eccentric glenoid reaming and occasionally bone grafting. More recently reverse total shoulder arthroplasty (rTSA) with or without bone grafting and posterior augmented glenoids (PAGs) has been introduced. The PAG restores the native joint line while reaming a minimal amount of glenoid bone. The purpose of this study is to compare osteoarthritic shoulders with significant posterior glenoid wear treated with anatomic total shoulder arthroplasty (aTSA) using a PAG to shoulders without glenoid wear treated with aTSA using a standard all poly pegged glenoid.

METHODS

The patients' data in this study were retrospectively queried from prospectively acquired data in a multi-institutional IRB approved database. The study population consisted of 24 patients with osteoarthritis and posterior glenoid wear who were treated with aTSA using a PAG with a minimum of two-year follow-up. This population was age, sex, and follow-up matched to patients treated with an all poly non-augmented pegged glenoid (NAG) for osteoarthritis. Seven females and 17 males with an average age of 65.8 ± 11.5 years received a posterior augmented glenoid. The control group consisted of 7 females and 17 males with an average age of 66.4 ± 9.1 years who underwent aTSA for osteoarthritis using an all poly standard glenoid. These age, gender, and follow-up matched patients were evaluated and scored preoperatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI scoring metrics; active abduction, elevation, and external rotation were also measured. A Grashey and axillary lateral radiograph was evaluated at two-year follow-up. The Shoulder Arthroplasty Subluxation Index was used to determine the degree of humeral component subluxation on the glenoid component. A Student's two-tailed, unpaired t-test was used to identify differences in preoperative and postoperative results, where p < 0.05 denoted a significant difference.

RESULTS

All patients demonstrated significant improvements in pain and function with the primary aTSA. Sixty per-cent of PAG shoulders had a radiolucent line with an average radiographic line score of 1.10, and 33.3% of NAG had a radiolucent line with an average radiographic line score of 0.438. One glenoid in the PAG group is radiographically but not clinically loose. In the PAG group, the Grashey view showed that 18/20 humeral heads were centered with the two remaining joints demonstrating superior subluxation. On the axillary lateral in the PAG group, 17/20 humeral heads were centered, and three were anteriorly subluxated; none were posteriorly subluxated. There were no differences in any of the measured postoperative clinical outcomes or any difference in improvement between the two groups.

DISCUSSION

At a minimum of two-year follow-up, there were no statistical clinical differences between the PAG and NAG groups despite the PAG group being disadvantaged with posterior worn glenoids. There were no revisions in either group. No humeral heads resubluxated posteriorly. The PAG group had a higher incidence of lucent lines. Based on this short-term follow-up, a posterior augmented glenoid is a viable option for the posterior worn osteoarthritic glenoid.

Reverse Shoulder Arthroplasty Augments for Glenoid Wear. Comparison of Posterior Augments to Superior Augments

INTRODUCTION

Patients who are candidates for a reverse total shoulder arthroplasty (rTSA) may have varying amounts and patterns of glenoid wear. The usual treatment of these deformities has been eccentric reaming or bone grafting. Eccentric reaming often removes a large amount of subchondral bone. Bone grafting is technically more difficult and introduces another mode of failure if the graft does not heal. The purpose of this study is to evaluate patients undergoing a rTSA with concomitant superior or posterior glenoid wear who were treated with a superior augmented baseplate (SAB) or posterior augmented baseplate (PAB) without eccentric reaming or bone grafting.

MATERIALS AND METHODS

Prospectively obtained data were queried from a multi-institutional IRB-approved database. Preoperative and postoperative data were analyzed from 39 patients who received a primary rTSA with either an 8° PAB or a 10° SAB and a minimum of 2 years follow-up. Twenty-four (10 females and 14 males, aged 72.3 ± 8.2 years) received a primary rTSA shoulder with a PAB. Fifteen patients (4 females and 11 males, aged 71.7 ± 9.2 years) received a primary rTSA shoulder with a SAB. Each patient was scored preoperatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI metrics. Active abduction, forward flexion, and active and passive external rotation with the arm at the side were also measured. The average follow-up for rTSA patients with a PAB was 25.6 ± 3.1 months, and the average follow-up for rTSA patients with a SAB was 32.5 ± 6.5 months. A Student's two-tailed, unpaired t-test was used to identify differences in preoperative and postoperative results, where p < 0.05 denoted a significant difference.

RESULTS

All patients in both groups demonstrated significant improvements in pain and function following treatment with the reverse shoulder arthroplasty. The PAB rTSA cohort had a scapular notching rate of 6.3%, whereas the SAB rTSA cohort had a scapular notching rate of 14.3%. The PAB outperformed the SAB with the ASES, Constant, and active forward elevation measures.

DISCUSSION

The PAB group outperformed the SAB group with the ASES and Constant outcome scores and forward flexion. The reason for this is unknown; however, it may be due to the posterior augment baseplate itself tensioning the remaining external rotators better than the superior augment, or it may be that the posterior augment group had a better posterior cuff. Both implant groups had no revisions or dislocations and had a low notching rate. It appears that a SAB for superior glenoid wear and a PAB for posterior glenoid wear are viable simple solutions in patients undergoing a rTSA, where each preserves glenoid bone and eliminates the need for glenoid bone grafting.