Healing of reamed glenoid bone articulating with a metal humeral hemiarthroplasty: a canine model

Shoulder Hemiarthroplasty with Nonprosthetic Glenoid Arthroplasty: The Ream-and-Run Procedure

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Glenoid component wear and loosening are the principal failure modes of anatomic total shoulder arthroplasty (aTSA).

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The ream-and-run (RnR) procedure is an alternative glenohumeral arthroplasty for patients who wish to avoid the risks and limitations of a prosthetic glenoid component.

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During the RnR procedure, the arthritic glenoid is conservatively reamed to a single concavity, while the prosthetic humeral component and soft tissues are balanced to provide both mobility and stability of the joint.

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The success of the RnR procedure depends on careful patient selection, preoperative education and engagement, optimal surgical technique, targeted rehabilitation, and close postoperative communication between the surgeon and the patient.

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While the RnR procedure allows high levels of shoulder function in most patients, the recovery can be longer and more arduous than with aTSA.

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Patients who have undergone an RnR procedure occasionally require a second closed or open procedure to address refractory shoulder stiffness, infection, or persistent glenoid-sided pain. These second procedures are more common after the RnR than with aTSA.

Does the degree of osteoarthritis influence the clinical outcome after anatomic total shoulder arthroplasty?

BACKGROUND

The degree of preoperative osteoarthritis has been shown to influence the postoperative outcome and the patients' satisfaction rate in hip and knee joint replacement surgery. However, no corresponding information is available for total shoulder arthroplasty (TSA). We therefore set out to evaluate the influence of preoperatively measured end-stage osteoarthritis on the postoperative clinical outcome of TSA.

METHODS

A retrospective analysis of 103 anatomic total shoulder replacements (96 patients) was performed. Patients were evaluated radiologically with X-rays in two planes and clinically using the Constant and Murley score (CS) and the self-reported satisfaction with the result. The degree of osteoarthritis was radiographically analyzed with the aid of the classifications according to Kellgren/Lawrence, Gerber, Guyette, and Allain and according to whether complete narrowing of the glenohumeral joint was present or not [bone-on-bone contact (BOB) or no bone-on-bone contact (No BOB)].

RESULTS

The clinical results of TSA did not differ significantly among the various stages of osteoarthritis in any of the classifications (p > 0.05). The CS was significantly higher postoperatively for both the BOB and the No BOB group (p < 0.0001). Patients with BOB had a significantly lower CS preoperatively than patients with No BOB (p = 0.0172). In addition, the preoperative pain level was significantly higher in patients with BOB (p = 0.014). Postoperatively, no significant difference in CS (p = 0.6738) was found between the BOB group and the No BOB group. The mean improvement in CS was not statistically significant (p = 0.2218).

CONCLUSION

In contrast to hip and knee joint replacement procedures, a milder grade of osteoarthritis does not adversely influence the functional result or subjective satisfaction rate after TSA. The degree of osteoarthritis on conventional X-rays has no bearing on the postoperative clinical outcome. Therefore, the decision on when to carry out anatomic total shoulder arthroplasty should depend on the patient's pain level and loss of quality of life.

Return to Sport Following Hemiarthroplasty With Concentric Reaming Versus Total Shoulder Arthroplasty: A Matched Pair Analysis

The purpose of this study was to establish functional outcomes regarding return to sport activity for patients receiving anatomical total shoulder arthroplasty (aTSA) vs the ream and run procedure (hemi RR). Patients who underwent hemi RR and who underwent aTSA with a polyethylene glenoid component for end-stage glenohumeral arthritis were retrospectively identified from 2000 to 2014. Patients were matched regarding age, body mass index, sex, and hand dominance. Patients were surveyed to determine their level of sport and satisfaction after surgery. At a mean follow-up of 69.1±24.8 months, a total of 26 hemi RR and 30 aTSA patients met inclusion/exclusion criteria. Mean±SD age at the time of surgery was 53.0±8.5 years. There was no statistical difference between the two cohorts regarding patients who reported no postoperative problems (69.2% vs 76.7%, P=.529), reoperation (11.5% vs 6.7%, P=.522), return to overall sport (94.4% vs 86.4%, P=.395), return to high-demand upper-extremity sport (92.3% vs 81.3%, P=.390), and return to same or better level of intensity sport (83.3% vs 72.7%, P=.424). Patients returned to sport at a mean of 7.5±5.7 months and 6.2±3.6 months in the hemi RR and aTSA cohorts, respectively (P=.485). Radiographic measurements of medialization (mean, -2.4±5.0 vs -2.2±5.7; P=.913) and postoperative decentering (mean, 3.6%±2.6% vs 4.3%±3.3%; P=.795) were equivalent for the two cohorts. Hemi RR was found to have high and equivalent rates of sporting outcomes, clinical outcomes, and radiographic outcomes compared with aTSA. As appropriately indicated patients are counseled for surgery, realistic expectations regarding sports should be discussed. [Orthopedics. 2019; 42(5):276-284.].

Comparative analysis of work-related outcomes in hemiarthroplasty with concentric glenoid reaming and total shoulder arthroplasty

BACKGROUND

Anatomic total shoulder arthroplasty (aTSA) has demonstrated high levels of return to work, although there are fears of glenoid component loosening with higher work demand.

METHODS

A retrospective query was performed of all patients who received hemiarthroplasty with ream-and-run resurfacing (Hemi RR) between 2005 and 2014. Included patients were matched to an aTSA cohort by age, body mass index, sex, and hand dominance. Preoperative and postoperative work status, by level of duty and occupation, was collected.

RESULTS

Twenty-five patients receiving Hemi RR and 28 patients receiving TSA completed this questionnaire (82.8% compliance). Mean follow-up was 69.1 ± 24.8 months. In total, 100% of Hemi RR patients returned to work, and 89.3% of TSA patients returned to work (P = .091). The Hemi RR patients had higher rates of return to work for heavy-duty workers only (7 of 7 vs. 2 of 4, P = .038), although only 1 patient in the TSA group reported failure to work was due to shoulder reasons. Mean duration of return to work was 2.5 ± 4.8 months for patients receiving Hemi RR and 1.98 ± 2.6 months for those receiving TSA (P = .653).

CONCLUSIONS

Hemi RR had a high return to heavy-duty work, likely due to fewer surgeon-imposed restrictions. The results of this study may help manage return to work expectations after Hemi RR according to the level of duty and suggest Hemi RR is a viable option for heavy-duty laborers with end-stage glenohumeral arthritis.

Short-term Clinical Outcomes of Hemiarthroplasty With Concentric Glenoid Reaming: The Ream and Run Procedure

The purpose of this study was to evaluate the short-term clinical and radiographic outcomes of humeral hemiarthroplasty and concentric glenoid reaming ("ream and run" procedure) and to compare the outcomes with those of total shoulder arthroplasty (TSA) for glenohumeral arthritis. Patients with glenohumeral arthritis who underwent the ream and run procedure with a minimum follow-up of 2 years were retrospectively reviewed. The primary outcome was revision to TSA. Secondary outcome measures included functional outcome scores, range of motion, and radiographic assessment. The outcome measures were compared with those of age- and sex-matched control patients who underwent anatomic TSA during the study period. One patient in the ream and run group required revision to TSA 14 months after the surgery because of excessive shoulder pain. There were significant improvements in the postoperative outcome scores and range of motion and external rotation in the ream and run group. Postoperative radiographs showed concentric glenoids without posterior subluxation in all except 1 shoulder. The outcome measures in the ream and run group were similar to those in the TSA control group except for active forward elevation and external rotation. The ream and run procedure provides improved pain relief and shoulder function at short-term follow-up for patients with shoulder arthritis. [Orthopedics. 2018; 41(6):e854-e860.].

Treatment of Articular Cartilage Injuries in the Glenohumeral Joint

Articular cartilage injuries in the glenohumeral joint present a unique and difficult problem for the patient and surgeon alike. Various etiologies exist for the development of these cartilage lesions; therefore, treatment options are vast and must be chosen thoughtfully, especially in the young, active patient. Across all treatment modalities, the goal is for the patient to regain lasting function and mobility while decreasing pain.

Survivorship of Hemiarthroplasty With Concentric Glenoid Reaming for Glenohumeral Arthritis in Young, Active Patients With a Biconcave Glenoid

INTRODUCTION

Hemiarthroplasty with concentric glenoid reaming (known as "ream and run") may be an option for treating glenohumeral arthritis in younger patients with a biconcave glenoid. The goal of this study was to evaluate early results of this technique.

METHODS

Two senior, fellowship-trained shoulder surgeons (G.R.W. and M.D.L.) performed a retrospective review of 23 patients (24 shoulders) with a biconcave glenoid and end-stage degenerative glenohumeral arthritis treated with hemiarthroplasty with concentric glenoid reaming. The mean patient age at the time of surgery was 50 years. We evaluated the Penn Shoulder Score (PSS), Single Assessment Numeric Evaluation (SANE) score, and Simple Shoulder Test (SST) score or the time to revision surgery.

RESULTS

Twenty-four humeral hemiarthroplasties with concentric glenoid reaming were performed in 23 patients. Twenty patients (21 shoulders) reached the end point of 2-year follow-up or revision surgery. Six shoulders (25%) required revision surgery at an average of 2.7 years (range, 0.7 to 7.2 years), and three were lost to follow-up. The remaining 14 patients (15 shoulders) were followed up for an average of 3.7 years (range, 2.3 to 4.9 years). At 2-year follow-up, these 15 shoulders did not require revision surgery and had an average SANE score, PSS, and SST score of 74.5%, 82.9, and 10.4, respectively. Increasing age correlated positively with the SANE score (r = 0.62; P = 0.015), PSS (r = 0.52; P = 0.047), and SST score (r = 0.63; P = 0.012). Early postoperative forward elevation correlated weakly with the PSS (r = 0.24; P = 0.395), and early postoperative external rotation correlated moderately with the PSS (r = 0.53; P = 0.044). Final external rotation correlated moderately with the PSS (r = 0.69; P = 0.005).

DISCUSSION

Modest results were achieved with a hemiarthroplasty and concentric glenoid reaming in young patients with end-stage glenohumeral arthritis and a biconcave glenoid. Younger age and stiffness were associated with worse outcomes. Given the high revision rate and the percentage of patients who had unsatisfactory results, this procedure should be performed only after careful patient selection. Patients who are willing and able to undergo aggressive physical therapy focused on achieving early range of motion are more likely to have a satisfactory outcome after humeral hemiarthroplasty with concentric glenoid reaming.

Clinical and Radiographic Outcomes of the Ream-and-Run Procedure for Primary Glenohumeral Arthritis

BACKGROUND

The ream-and-run procedure can provide improvement in shoulder function and comfort for selected patients with primary glenohumeral arthritis who wish to avoid a prosthetic glenoid component. The purpose of this study was to evaluate factors associated with medialization of the humeral head after this procedure as well as the relationship of medialization to the clinical outcome.

METHODS

We collected patient, shoulder, and procedure characteristics along with Simple Shoulder Test (SST) scores before surgery and at the time of follow-up. Medialization was determined by comparing the position of the humeral head prosthesis in relation to the scapula on postoperative baseline radiographs made within 6 weeks after surgery with that on comparable follow-up radiographs made ≥18 months after surgery.

RESULTS

Two-year clinical outcomes were available for 101 patients (95% were male). Comparable radiographs at postoperative baseline and follow-up evaluations were available for 50 shoulders. For all patients, the mean SST score (and standard deviation) increased from 4.9 ± 2.8 preoperatively to 10.3 ± 2.4 at the latest follow-up (p < 0.001). Significant clinical improvement was observed for glenoid types A2 and B2. Shoulders with a type-A2 glenoid morphology, with larger preoperative scapular body-glenoid angles, and with lower preoperative SST scores, were associated with the greatest clinical improvement. Clinical outcome was not significantly associated with the amount of medialization.

CONCLUSIONS

The ream-and-run procedure can be an effective treatment for advanced primary glenohumeral osteoarthritis in active patients. Further study will be necessary to determine whether medialization affects the clinical outcome with follow-up of >2 years.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Assessment of glenoid chondral healing: comparison of microfracture to autologous matrix-induced chondrogenesis in a novel rabbit shoulder model

BACKGROUND

Management of glenohumeral arthrosis in young patients is a considerable challenge, with a growing need for non-arthroplasty alternatives. The objectives of this study were to develop an animal model to study glenoid cartilage repair and to compare surgical repair strategies to promote glenoid chondral healing.

METHODS

Forty-five rabbits underwent unilateral removal of the entire glenoid articular surface and were divided into 3 groups--untreated defect (UD), microfracture (MFx), and MFx plus type I/III collagen scaffold (autologous matrix-induced chondrogenesis [AMIC])--for the evaluation of healing at 8 weeks (12 rabbits) and 32 weeks (33 rabbits) after injury. Contralateral shoulders served as unoperated controls. Tissue assessments included 11.7-T magnetic resonance imaging (long-term healing group only), equilibrium partitioning of an ionic contrast agent via micro-computed tomography (EPIC-μCT), and histologic investigation (grades on International Cartilage Repair Society II scoring system).

RESULTS

At 8 weeks, x-ray attenuation, thickness, and volume did not differ by treatment group. At 32 weeks, the T2 index (ratio of T2 values of healing to intact glenoids) was significantly lower for the MFx group relative to the AMIC group (P = .01) whereas the T1ρ index was significantly lower for AMIC relative to MFx (P = .01). The micro-computed tomography-derived repair tissue volume was significantly higher for MFx than for UD. Histologic investigation generally suggested inferior healing in the AMIC and UD groups relative to the MFx group, which exhibited improvements in both integration of repair tissue with subchondral bone and tidemark formation over time.

DISCUSSION

Improvements conferred by AMIC were limited to magnetic resonance imaging outcomes, whereas MFx appeared to promote increased fibrous tissue deposition via micro-computed tomography and more hyaline-like repair histologically. The findings from this novel model suggest that MFx promotes biologic resurfacing of full-thickness glenoid articular injury.

[Posttraumatic arthrosis of the glenohumeral joint. From partial resurfacing to reverse shoulder arthroplasty]

BACKGROUND

Arthroplasty of symptomatic sequelae after fractures of the proximal humerus is a demanding procedure for surgeons. Exact preoperative planning is crucial in order to achieve acceptable functional results.

OBJECTIVE

Discussion of preoperative considerations in planning the procedure and choosing the appropriate implant taking the osseous anatomy and surrounding soft tissue situation into consideration.

METHODS

Selective literature review and description of personal experience.

RESULTS

The geometry and consolidation status of bone fragments as well as the conditions of the surrounding soft tissue have to be taken into account and influence the choice of implant used. Insufficient planning will not only cause intraoperative technical problems but can also greatly influence the subjective patient assessment of the postoperative outcome. Unequal strain distribution can cause early loosening of components resulting in malfunctioning of the implant. In this respect, knowledge of the position and consolidation status of fractured tuberosities with respect to the humeral shaft is essential and allows an approximate estimation of the achievable outcome. This is taken into account by the classification of Boileau which can also help to decide on which type of implant to use. Because such cases are scarce, reported results in the literature are heterogeneous, which is discussed in this article.

CONCLUSION

Each case needs a thorough and individualized preoperative assessment along with exact planning and should therefore be reserved for experienced shoulder surgeons only.

The ream and run: not for every patient, every surgeon or every problem

PURPOSE

The purpose of this paper is to provide some essential and basic information concerning the ream and run technique for shoulder arthroplasty.

METHODS

In a total shoulder arthroplasty, the humeral head prosthesis articulates with a polyethylene glenoid surface placed on the bone of the glenoid. Failure of the glenoid component is recognised as the principal cause of failure of total shoulder arthroplasty. By contrast, in the ream and run procedure, the humeral head prosthesis articulates directly with the glenoid, which has been conservatively reamed to provide a stabilising concavity and maximal glenohumeral contact area for load transfer. While no interpositional material is placed on the surface of the glenoid, animal studies have demonstrated that the reamed glenoid bone forms fibrocartilage, which is firmly fixed to the reamed bony surface. Glenohumeral motion is instituted on the day of surgery and continued daily after surgery to mold the regenerating glenoid fibrocartilage. When the healing process is complete - as indicated by a good and comfortable range of motion - exercises and activities are added progressively without concern for glenoid component failure. 

RESULTS

The experience to date indicates that a technically well done ream and run procedure can restore high levels of comfort and function to carefully selected patients with osteoarthritis, capsulorrhaphy arthroplathy, and posttraumatic arthritis.

CONCLUSIONS

Patients considering the ream and run procedure should understand that this technique avoids the risks and limitations associated with a polyethylene glenoid component, but that it requires strong motivation to follow through on a rehabilitation course that may require many months. The outcome of this procedure depends on the body's regeneration of a new surface for the glenoid and requires rigorous adherence to a daily exercise program. This paper explains in detail the principal factors in patient selection and the key technical elements of the procedure. Clinical examples and outcomes are demonstrated.

Shoulder joint hemiarthroplasty for treatment of a severe osteochondritis dissecans lesion in a dog

INTRODUCTION

Partial resurfacing of the humeral head has been reported in humans to treat humeral osteochondritis dissecans. The aim is to describe a custom-made humeral resurfacing prosthesis for treatment of severe humeral head osteochondritis disse-cans in a dog.

CASE REPORT

A seven-month-old female entire St. Bernard dog was presented with a 10 week history of severe left thoracic limb lameness. Radiography, arthroscopy and magnetic resonance imaging confirmed an extensive osteochondritis dissecans lesion affecting the caudal, medial and central regions of the humeral head. A prosthesis designed from computed tomography (CT) images was manufactured in polished stainless steel alloy with a hydroxyapatite coated base and central finned humeral stem for cementless insertion. A standard caudal approach to the shoulder was used to place the prosthesis following reaming of the caudal humeral head.

RESULTS

Radiography and CT imaging revealed appropriate topographical placement on the humerus. Force plate analysis demonstrated initial reduction in ground reaction force at six weeks, followed by gradual improvement at three months. There was no radiographic evidence of implant loosening and the range of shoulder joint motion was comparable to the contralateral joint at three months; these findings were maintained to final follow-up at 24 months.

CLINICAL SIGNIFICANCE

Placement of a humeral head resurfacing prosthesis was an effective technique for the management of severe osteochondritis dissecans-related shoulder lameness. To the authors' knowledge, this is the first report of the clinical use of shoulder hemiarthroplasty in a dog.

Addressing glenoid bone deficiency and asymmetric posterior erosion in shoulder arthroplasty

Glenoid bone deficiency and eccentric posterior wear are difficult problems faced by shoulder arthroplasty surgeons. Numerous options and techniques exist for addressing these issues. Hemiarthroplasty with concentric glenoid reaming may be a viable alternative in motivated patients in whom glenoid component failure is a concern. Total shoulder arthroplasty has been shown to provide durable pain relief and excellent function in patients, and numerous methods and techniques can assist in addressing bone loss and eccentric wear. However, the ideal amount of version correction in cases of severe retroversion has not yet been established. Asymmetric reaming is a commonly used technique to address glenoid version, but correction of severe retroversion may compromise bone stock and component fixation. Bone grafting is a technically demanding alternative for uncontained defects and has mixed clinical results. Specialized glenoid implants with posterior augmentation have been created to assist the surgeon in correcting glenoid version without compromising bone stock, but clinical data on these implants are still pending. Custom implants or instruments based on each patient's unique glenoid anatomy may hold promise. In elderly, sedentary patients in whom bone stock and soft-tissue balance are concerns, reverse total shoulder arthroplasty may be less technically demanding while still providing satisfactory pain relief and functional improvements.

Shoulder arthrodesis in 14 dogs

OBJECTIVES

To report surgical technique and clinical outcome of shoulder arthrodesis in dogs.

STUDY DESIGN

Multicenter clinical case series.

ANIMALS

Dogs (n = 14).

METHODS

Shoulder arthrodesis featured craniolateral plate and screw application, with application of a 2nd plate and screws craniolaterally or caudolaterally in 5 shoulders. Implants included the locking string of pearls (SOP)™ plate in 7 shoulders. Subjective preoperative, 5-8 weeks postoperative, and 11-16 weeks postoperative clinical and radiographic findings were documented. Owner questionnaire evaluation of outcome was performed 6-20 months postoperatively.

RESULTS

Mean angle of arthrodesis was 114° (range 102°-122°). Progression of arthrodesis was noted in 13/14 cases at both the 5-8 and 11-16 weeks postoperative radiographic assessments. Nine complications occurred in 7/14 dogs, graded as catastrophic in 2/9, major in 2/9, and minor in 5/9. Where morbidity was successfully managed, 11-16-week and 6-10-month postoperative limb function was positive on both veterinary and owner evaluations in almost all cases, and in several, functional lameness was considered sufficiently mild as to be imperceptible on subjective veterinary evaluation. Where present, limb circumduction was noted as the major feature of persistent lameness.

CONCLUSIONS

Shoulder arthrodesis in dogs results in acceptable limb function and should be considered for the management of debilitating shoulder pathology despite a high incidence of complications. Application of the SOP plate to aid shoulder arthrodesis warrants further study.

Proximal focal humeral deficiency in a large breed dog

A 26-week-old female Boerboel was referred for evaluation of progressive left thoracic limb lameness. Computed tomography and radiographic evaluation revealed radiolucency of the caudal region of the proximal humeral metaphysis, absence of the humeral head, and gross distortion of the glenoid. Given the severe glenohumeral deformation, arthrodesis of the left shoulder was performed using orthogonal locking bone plates, lag screw fixation, and bone grafting. Despite late implant failure, arthrodesis was successful in this case, and satisfactory limb function was restored. To the author's knowledge, this is the first report of a case of a focal developmental deficiency of the proximal humerus reported in a dog.

The prognosis for improvement in comfort and function after the ream-and-run arthroplasty for glenohumeral arthritis: an analysis of 176 consecutive cases

BACKGROUND

Knowledge of the factors affecting the prognosis for improvement in function and comfort with time after shoulder arthroplasty is important to clinical decision-making. This study sought to identify some of these factors in 176 consecutive patients undergoing the ream-and-run procedure.

METHODS

The time course for improvement in patient function and comfort was determined for the entire group as well as for subsets by sex, age, diagnosis, preoperative function, and surgery date. Patients having repeat surgery were analyzed in detail.

RESULTS

Shoulder comfort and function increased progressively after the ream-and-run procedure, reaching a steady state by approximately twenty months. The shoulders in 124 patients with at least two years of follow-up were improved by a minimal clinically important difference. The shoulders in sixteen patients with at least two years of follow-up were not improved by the minimal clinically important difference. Twenty-two patients had repeat procedures, but only seven had revision to a total shoulder arthroplasty. Fourteen patients did not have either a known revision arthroplasty or two years of follow-up. The best prognosis was for male patients over the age of sixty years, with primary osteoarthritis, no prior surgical procedures, a preoperative score on the simple shoulder test of ≥5 points, and surgery after 2004. Repeat surgical procedures were more common in patients who had a greater number of surgical procedures before the ream-and-run surgery.

CONCLUSIONS

This study is unique in that it characterizes the factors affecting the time course for improvement in shoulder comfort and function after a ream-and-run procedure. Improvement occurs after this procedure for at least 1.5 years. This procedure appears to be best suited for an older male patient with reasonable preoperative shoulder function without prior shoulder surgery.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for authors for a complete description of levels of evidence.

Recent advances in shoulder research

Shoulder pathology is a growing concern for the aging population, athletes, and laborers. Shoulder osteoarthritis and rotator cuff disease represent the two most common disorders of the shoulder leading to pain, disability, and degeneration. While research in cartilage regeneration has not yet been translated clinically, the field of shoulder arthroplasty has advanced to the point that joint replacement is an excellent and viable option for a number of pathologic conditions in the shoulder. Rotator cuff disease has been a significant focus of research activity in recent years, as clinicians face the challenge of poor tendon healing and irreversible changes associated with rotator cuff arthropathy. Future treatment modalities involving biologics and tissue engineering hold further promise to improve outcomes for patients suffering from shoulder pathologies.

Biological resurfacing for early osteoarthritis of the shoulder

Young patients with degenerative shoulder disease are a therapeutic challenge. To try to delay a shoulder arthroplasty, biological interpositional arthroplasty has been proposed to provide a biologically active bearing surface that could eventually results in the formation of fibrocartilage, fibrous tissue, or hyaline cartilage. Anterior capsule, autogenous fascia lata, Achilles tendon allograft, lateral meniscus allograft, human dermis, and porcine small intestine submucosa have been used as interposition material, either alone or in combination with a hemiarthroplasty or humeral resurfacing procedure. Some investigators have reported favorable long-term results, although others have found this procedure unreliable. Several variables are unknown at present, such as the best biological resurfacing device, healing potential, possible antigenic responses, optimal fixation technique or position, aftercare restrictions. Further prospective studies with long follow-up are necessary to provide data that will help to define the role of biological glenoid resurfacing in young patients with glenohumeral arthritis.

Animal models for translational research on shoulder pathologies: from bench to bedside

Several animal models have been used for in vivo and in vitro shoulder research. In vitro models, consisting of cadaveric specimens, are useful in providing basic understanding of the functioning of the shoulder and for biomechanical experiments. In vivo models provide the means to model living phenomena, such as tendon healing process, tendinopathy, instability, and adaptive responses to surgery. However, intrinsic differences among different species make translation to human shoulder pathologies difficult. Most of the animals used in experimental settings are quadrupeds, using the forelimbs for weight-bearing during locomotion, with no or minimal overhead activity. The various animal models already used to study shoulder pathologies are presented in this article. However, there is a lack of validation for these animal models, which provides challenge to the further research in this field.

The glenoid in total shoulder arthroplasty

Management of glenohumeral arthrosis with a total shoulder prosthesis is becoming increasingly common. However, failure of the glenoid component remains one of the most common causes for failure. Our understanding of this problem has evolved greatly since the first implants were placed in the 1970's. However glenoid failure remains a challenging problem to address and manage. This article reviews the current knowledge regarding the glenoid in total shoulder arthroplasty touching on anatomy, component design, implant fixation, causes of implant failure, management of glenoid failure and alternatives to glenoid replacement.

Shoulder hemiarthroplasty with concentric glenoid reaming in patients 55 years old or less

BACKGROUND

Glenohumeral arthritis in younger individuals is challenging because of the complex pathology, need for extended durability, and high expectations of the patients. Humeral hemiarthroplasty combined with concentric glenoid reaming is a surgical option for the management of glenohumeral arthritis that avoids the risks of glenoid component failure and avoids the challenges of tissue interposition. The results of this procedure in young patients have not been previously reported.

METHODS

Sixty-five shoulders in patients who were 55 years old or less at the time of surgery underwent humeral hemiarthroplasty combined with concentric glenoid reaming and were followed for a minimum of 2 years or until the time of revision surgery. Patient self-assessments of shoulder comfort and function were compared before and after surgery. For 22 of these shoulders, standardized radiographs were available for follow-up evaluation.

RESULTS

Nine shoulders required revision surgery. These shoulders had 3 ± 3 prior surgeries, in comparison to 1 ± 1 prior surgeries for the unrevised group. For the 56 unrevised shoulders, the number of Simple Shoulder Test functions that could be performed improved from a mean of 4.1 before surgery to a mean of 9.5 at an average follow-up of 43 months (range, 24-85) (P < .001). For the 22 shoulders with radiographic follow-up, medial glenoid erosion averaged 1.1 mm (range, 0.0-6.3 mm) at an average of 44 months after the procedure.

CONCLUSION

In selected patients 55 years or younger with glenohumeral arthritis, this procedure can provide significant improvement in self-assessed shoulder comfort and function.

A quantitative method for determining medial migration of the humeral head after shoulder arthroplasty: preliminary results in assessing glenoid wear at a minimum of two years after hemiarthroplasty with concentric glenoid reaming

HYPOTHESIS

Glenoid erosion and medial migration of the humeral head prosthesis have been observed after most types of shoulder arthroplasty. A method of measuring the change in humeral head position with time after shoulder prosthetic arthroplasty was applied it to 14 shoulders that underwent humeral hemiarthroplasty with concentric glenoid reaming. We hypothesized that the measurement technique would be reproducible and that the rate of wear would be small in the series of shoulders studied.

MATERIALS AND METHODS

Standardized anteroposterior and axillary radiographs were obtained after surgery. Two examiners measured the position of the humeral head center in relation to scapular reference coordinates for the anteroposterior and axillary projections and plotted these values against time after surgery. The change in position was characterized as the slope of this plot. Shoulders were included if there were at least 3 sets of postoperative films, the last being at least 2 years after surgery.

RESULTS

The slopes measured by the 2 examiners agreed within 0.5 mm/y for the anteroposterior and the axillary projections. For the series of shoulder arthroplasties, the rate of movement of the head center toward the scapula was less than 0.4 mm/y for either examiner in either projection.

DISCUSSION

Medial migration is a concern after any type of shoulder arthroplasty, whether a hemiarthroplasty, a biological interpositional arthroplasty, or a total shoulder arthroplasty. Quantifying the rate of medial migration over time after shoulder arthroplasty is an important element of clinical follow-up.

CONCLUSIONS

This is an inexpensive, practical, and reproducible method that can be used to determine the rate of medial migration of the humeral head on plain radiographs after shoulder arthroplasty. The average rate of medial migration in the shoulders in this study was small.

Treatment of glenohumeral arthrosis

The successful diagnosis and treatment of glenohumeral arthrosis in the young and active patient can be challenging to even the most experienced of clinicians. A thorough preoperative evaluation, including a detailed understanding of patient expectations, facilitates the selection of a treatment strategy. Arthroscopy is the gold standard for detecting chondral injuries, and it is increasingly used as an effective first line of management. In patients who fail arthroscopic debridement and reparative techniques, further treatment should proceed with an algorithmic decision-making approach encompassing patient-based and disease-based factors. Restorative and reconstructive techniques may provide improvements in pain and functional outcome while delaying the need for total shoulder arthroplasty, although the longevity of these treatments has yet to be established in the literature. Hemiarthroplasty and total shoulder arthroplasty have historically proven to be the most durable and reliable options in properly selected patients. However, concerns about progressive glenoid erosion and glenoid component loosening have led many to pursue alternative nonarthroplasty techniques for the management of arthrosis in active young individuals.

The glenoid in shoulder arthroplasty

Total shoulder arthroplasty is a common treatment for glenohumeral arthritis. One of the most common failure modes of total shoulder arthroplasty is glenoid loosening, causing postoperative pain, limitation of function, and potentially, the need for revision surgery. The literature has devoted considerable attention to the design of the glenoid component; efforts to better understand the biomechanics of the reconstructed glenohumeral joint and identify factors that contribute to glenoid component loosening are ongoing. This article reviews the current state of knowledge about the glenoid in total shoulder arthroplasty, summarizing the anatomic parameters of the intact glenoid, variations in component design and fixation, the mechanisms of glenoid loosening, the outcomes of revision surgery in the treatment of glenoid component failure, and alternative treatments for younger patients.

Arthroplasty in the young patient

Shoulder pain and loss of function caused by degenerative joint disease is extremely disabling to young people who have an active lifestyle. If non-operative and minimally invasive treatment fails, shoulder arthroplasty is a reasonable option. This article reviews the options and indications for their use in shoulder disability in the young patient.

Nonprosthetic glenoid arthroplasty with humeral hemiarthroplasty and total shoulder arthroplasty yield similar self-assessed outcomes in the management of comparable patients with glenohumeral arthritis

The risk of glenoid component failure has led us to explore nonprosthetic glenoid arthroplasty coupled with humeral hemiarthroplasty, the "ream and run" (R&R) procedure, for the management of glenohumeral arthritis in active patients. We hypothesized that patients having a R&R procedure would have outcomes comparable with those of similar patients having a total shoulder arthroplasty (TSA). A case-matched control study compared 35 consecutive patients (32 men, 3 women) with an average age of 56 years, after R&R with matched controls having TSA. The respective Simple Shoulder Test (SST) scores for the R&R and TSA groups were 4.5 and 4.0 before surgery, 7.8 and 9.6 at 12 months, 8.3 and 10.2 at 18 months, 8.9 and 9.4 at 24 months, 9.4 and 9.6 at 30 months, and 9.5 and 10.0 at 36 months. The "ream and run" procedure can offer similar functional recovery to patients with total shoulder arthroplasty, although the time to recovery may be longer.

Biologic resurfacing of the arthritic glenohumeral joint: Historical review and current applications

In recent years there has been a resurgence of interest in the use of biologic resurfacing of the glenoid for the treatment of glenohumeral arthritis in younger patients. We review the history as well as the current applications of this procedure.

Shoulder arthroplasty: the socket perspective

Although much attention has been directed to the development of the humeral components used in shoulder arthroplasty, the major unsolved challenge lies on the glenoid side of the articulation. This challenge arises from difficulties resisting eccentric loading and providing adequate implant-bone fixation. Current glenoid component designs use polyethylene and polymethyl methacrylate and are prone to loosening, plastic deformation, particulate debris, and third-body wear. Metal-backed components present further challenges, and results have generally been disappointing. There is interest in biologic resurfacing procedures, including the interposition of fascia, capsule, or meniscal allograft and nonprosthetic glenoid arthroplasty, or what has become known as the "ream-and-run" procedure. Despite encouraging results, important questions remain unanswered about these procedures. However, each may warrant further exploration with a goal of providing an effective and durable approach to glenoid arthritis that avoids the risks associated with polymethyl methacrylate and polyethylene.