Biomechanical comparison of anatomic humeral head resurfacing and hemiarthroplasty in functional glenohumeral positions

Update on Shoulder Arthroplasties with Emphasis on Imaging

Shoulder pain and dysfunction may significantly impact quality of life. If conservative measures fail, advanced disease is frequently treated with shoulder arthroplasty, which is currently the third most common joint replacement surgery following the hip and knee. The main indications for shoulder arthroplasty include primary osteoarthritis, post-traumatic arthritis, inflammatory arthritis, osteonecrosis, proximal humeral fracture sequelae, severely dislocated proximal humeral fractures, and advanced rotator cuff disease. Several types of anatomic arthroplasties are available, such as humeral head resurfacing and hemiarthroplasties, as well as total anatomic arthroplasties. Reverse total shoulder arthroplasties, which reverse the normal ball-and-socket geometry of the shoulder, are also available. Each of these arthroplasty types has specific indications and unique complications in addition to general hardware-related or surgery-related complications. Imaging-including radiography, ultrasonography, computed tomography, magnetic resonance imaging, and, occasionally, nuclear medicine imaging-has a key role in the initial pre-operative evaluation for shoulder arthroplasty, as well as in post-surgical follow-up. This review paper aims to discuss important pre-operative imaging considerations, including rotator cuff evaluation, glenoid morphology, and glenoid version, as well as to review post-operative imaging of the various types of shoulder arthroplasties, to include normal post-operative appearances as well as imaging findings of complications.

Clinical results and 10-year survivorship of the Synthes Epoca resurfacing total shoulder arthroplasty

Aims

This prospective cohort study reports the 10-year survivorship, patient-reported outcome measures and radiographic outcomes of the first series of the Epoca resurfacing head total shoulder arthroplasty.

Methods

From July 2008 to July 2014, 59 Epoca resurfacing head total shoulder arthroplasties were implanted in 50 patients by a single surgeon. Minimum 4.8 year and maximum 11.3 year follow-up (mean: 7.9 years) was analysed using the latest available Oxford Shoulder Score. Kaplan-Meier survivorship analysis was performed with revision as the end point. Most recent radiographs were reviewed for component radiolucency, osteolysis and proximal humeral migration.

Results

Two shoulders underwent revision (3.4%); one for pain with posterior subluxation following a fall, the other for pain with failure of the glenoid. Kaplan-Meier analysis revealed 10-year survivorship of 98.2% (95% confidence intervals: 88.0%-99.8%). Mean Oxford Shoulder Score improved significantly compared to pre-operative values from 18.2 (5-45) to 46.6 (36-48) (p < 0.001). Fifty-three shoulders underwent radiographic analysis (89.8%). This revealed humeral radiolucency in two cases (3.8%), glenoid radiolucency in three cases (5.7%) and radiographic rotator cuff failure in eight cases (15.1%).

Conclusion

This prospective cohort study shows excellent 10-year survivorship, medium to long-term clinical and radiological results and for the Synthes Epoca resurfacing head total shoulder arthroplasty.

Evidence level

IV.

Early offset-increasing migration predicts later revision for humeral head resurfacing implants. A randomized controlled radiostereometry trial with 10-year clinical follow-up

In a randomized controlled setting, medium-term implant migration and long-term clinical outcomes were compared for the Copeland and the Global C.A.P. humeral head resurfacing implants (HHRI). Thirty-two patients (mean age 63 years) were randomly allocated to a Copeland (n = 14) or Global C.A.P. (n = 18) HHRI. Patients were followed for 5 years with radiostereometry, Constant Shoulder Score, and the Western Ontario Osteoarthritis of the Shoulder Index (WOOS). WOOS and revision status were also obtained cross-sectionally at a mean 10-year follow-up. At the 5-year follow-up, total translation (TT) was 0.75 mm (95% confidence interval [CI]: 0.53-0.97) for the Copeland HHRIs and 1.15 mm (95% CI: 0.85-1.46) for the Global C.A.P. HHRIs (p = 0.04), but the clinical scores were similar at all follow-ups. The cumulative risks of revision at 5 and 10 years were 29% and 43% for Copeland and 35% and 41% for Global C.A.P HHRIs (p > 0.7). No implants were loose at revision, but HHRIs that were later revised followed an early offset-increasing migration pattern with medial translation and lift-off resulting in a mean 0.53 mm (95% CI: 0.18-0.88) higher TT at the 1-year follow-up compared to non-revised HHRIs. In conclusion, the Global C.A.P. HHRI had higher TT compared with the Copeland HHRI, but clinical scores and revision rates were similar. Nonetheless, revision rates were high and challenge the use of HHRIs. Interestingly, an early radiostereometry evaluated HHRI migration pattern with increased off-set predicted later implant revision.

Correlação entre posicionamento do implante das artroplastias parciais de recobrimento do ombro e os resultados funcionais

Objective  The present study aimed to correlate functional outcomes and implant positioning in a case series of partial shoulder resurfacing arthroplasties.

Methods  A total of 25 patients were assessed for range of motion, functional outcome per the University of California at Los Angeles (UCLA) score and radiographic findings. Pre- and postoperative data were compared. In addition, patients were grouped according to the cervical-diaphyseal angle (CDA) determined by an anteroposterior radiography and to the retroversion angle (RVA) determined by an axillary radiography. A CDA from 130° to 140° and a RVA from 20° to 40° consisted in ideal positioning (anatomical standard). Data were analyzed using the Wilcoxon signed-rank test, analysis of variance (ANOVA) followed by the Kruskal-Wallis test or the Mann-Whitney test as appropriate.

Results  The mean follow-up time was 48.3 months (12 to 67 months). The postoperative functional score (31.5) was higher than the preoperative score (15.5) ( p  < 0.001). In 6 patients, the implant was in anatomical positioning, while implant positioning was considered “nonstandard” in 19 subjects. Seven patients had a CDA < 130°, and 14 patients had a CDA ranging from 130° to 140°; in addition, the CDA was > 140° in 4 subjects. The RVA was up to 20° in 15 patients and ranged from 20° to 40° in 10 subjects. Using these criteria to group patients, the postoperative clinical-functional parameters were not statistically different from the preoperative findings ( p  > 0.05).

Conclusion  Partial shoulder resurfacing results in significant postoperative functional recovery in patients with degenerative joint diseases. However, implant positioning assessed by CDA and RVA does not correlate with clinical-functional outcomes and, therefore, it is an inaccurate indicator of surgical success.

Level of Evidence IV; Case Series.

Inlay total shoulder arthroplasty for primary glenohumeral arthritis

Background

Anatomic total shoulder arthroplasty with a nonspherical humeral head and inlay glenoid replacement has been introduced in the past; however, clinical evidence remains limited. We hypothesized that patients with advanced glenohumeral arthritis demonstrate significant improvements in pain and function.

Methods

Prospective patient-reported outcomes (PROs) included the American Shoulder and Elbow Surgeons score, a pain visual analog scale, and satisfaction. Range of motion was compared to the preoperative status. A sensitivity analysis examined responder rates and compared them to literature thresholds using the minimal clinically important difference and substantial clinical benefit. The preoperative glenoid morphology was determined using the Walsh classification. Zone-specific periprosthetic radiolucent lines were quantified at the last follow-up.

Results

Thirty-nine shoulders in 36 patients (3 bilateral) with a mean age of 65.9 years (26 males, 13 females) and a mean follow-up of 41.0 months were included. Ninety-three percent had grade III osteoarthritis, and 7% grade II. The glenoid Walsh classification included A1 (25%), A2 (25%), B1 (22%), B2 (25%), and C (3%). All PROs improved significantly (P < .001) with a mean American Shoulder and Elbow Surgeons score from 30.4 to 77.1, a pain visual analog scale from 8.1 to 1.5, and excellent (9.1/10) patient satisfaction. PRO-related responder rates for minimal clinically important difference and substantial clinical benefit were ≥85%. Forward elevation improved from 107° to 155°, and external rotation from 22° to 51°. One intraoperative glenoid rim fracture led to advanced radiolucency; no other clinically relevant lucency was observed.

Conclusion

Treatment with inlay total shoulder arthroplasty demonstrated significant functional improvement, excellent pain relief, and patient satisfaction in patients with advanced shoulder arthritis and various glenoid morphology types. Our initial results provide further support for this new option in primary shoulder replacement.

Biomechanics of anatomic and reverse shoulder arthroplasty

The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is necessary, as the goal of anatomic total shoulder arthroplasty is to reproduce premorbid shoulder kinematics.With reported joint reaction forces up to 2.4 times bodyweight, failure to restore anatomy and therefore provide a stable fulcrum will result in early implant failure secondary to glenoid loosening.The high variability of proximal humeral anatomy can be addressed with modular stems or stemless humeral components. The development of three-dimensional planning has led to a better understanding of the complex nature of glenoid bone deformity in eccentric osteoarthritis.The treatment of cuff tear arthropathy patients was revolutionized by the arrival of Grammont's reverse shoulder arthroplasty. The initial design medialized the centre of rotation and distalized the humerus, allowing up to a 42% increase in the deltoid moment arm.More modern reverse designs have maintained the element of restored stability but sought a more anatomic postoperative position to minimize complications and maximize rotational range of motion. Cite this article: EFORT Open Rev 2021;6:918-931. DOI: 10.1302/2058-5241.6.210014.

Surgical treatments of atraumatic avascular necrosis of the shoulder

Humeral head atraumatic avascular necrosis is a rare diagnosis. It concerns young patients with a high functional demand. The treatments are mostly surgical. The radiographic classification of Cruess assesses the severity of the humeral head avascular necrosis and guides surgical indications. This chapter reports a review of the literature based on meta-analyses and clinical series. Surgical treatments may be conservative or prosthetic. Conservative treatments include core decompression, bone grafting and arthroscopic debridement. Prosthetic replacements are performed by resurfacing, hemiarthroplasty or total arthroplasty. For low-grade asvascular necrosis, core decompression may be functionally effective and doesn't impair later surgical procedures. For high grades, prosthetic replacements achieve good functional outcomes. Hemiarthroplasty should be preferred if the glenoid cartilage is intact, with low rates of wear complications and better long-term outcome than shoulder arthroplasty.

Shoulder resurfacing for treatment of focal defects and diffuse osteoarthritis

This article provides a review of the various options for the treatment of osteoarticular pathology of the shoulder. This can range from focal osteochondral defects to diffuse arthritis and can occur at any age. Although total shoulder arthroplasty and hemiarthroplasty are the most frequently used methods, they not generally suitable for younger patients under 60 years old due to the lack of long-term stability and deterioration. If conservative treatment is unsuccessful or not an option, resurfacing is an alternative procedure with good long-term results. The various methods that have been reported for resurfacing and partial resurfacing of the humeral head are described as well as the results of studies on these procedures. In this article the indications, biomechanics, outcomes and complications are outlined for the two resurfacing options preferred by the authors.

Resurfacing hemiarthroplasty versus stemmed hemiarthroplasty for glenohumeral osteoarthritis: a meta-analysis

Background

Though total shoulder arthroplasty (TSA) has been an acknowledged treatment option for glenohumeral osteoarthritis, resurfacing hemiarthroplasty (RHA) and stemmed hemiarthroplasty (SHA) may be preferred in some circumstances by surgeons, especially for treating young or active patients. However, decision-making between the RHA and SHA is controversial. Therefore, we conducted a meta-analysis to systematically compare two surgical procedures in terms of postoperative functional outcomes, range of motion (ROM), pain relief, complication rates, risk of revision.

Methods

The PubMed, Embase, Web of Science and Cochrane Library were searched from inception to January 1, 2020, for all articles that compared the clinical effectiveness and safety of RHA with SHA. All eligible studies were selected based on certain screening criteria. Two investigators independently conducted the quality assessment and extracted the data. Fixed-effect and random-effect models were used for pooled results according to the degree of heterogeneity. All statistical analyses were performed by employing Stata software 14.0.

Results

A total of six comparative studies involving 2568 shoulders (1356 RHA and 1212 SHA) were included in the final analysis. Patients were followed up for at least 1 year in each study. Pooled results showed that RHA was associated with a better visual analog scale (SMD 0.61, p = 0.001) but higher revision rates (OR 1.50, p = 0.016) when compared to SHA. There were no significant differences in functional outcomes, such as Constant-Murley score (SMD 0.06, P = 0.878), American Shoulder and Elbow Surgeons score (SMD 0.05, P = 0.880), Western Ontario Osteoarthritis of the Shoulder index (SMD 0.43, p = 0.258) and quick-Disabilities of the Arm, Shoulder and Hand score (SMD 0.06, p = 0.669). In addition, no differences were observed in forward flexion (SMD 0.16, p = 0.622), external rotation (SMD -0.17, P = 0.741) and overall complication rates (OR 1.42, p = 0.198).

Conclusion

This is the first meta-analysis to investigate the clinical efficacy and safety of RHA in comparison with SHA for the treatment of glenohumeral osteoarthritis. The results demonstrated that the two surgical techniques were equivalent in terms of postoperative functional outcomes and complication rate. However, RHA provided greater pain relief but posed a higher risk for revision than SHA. More high-quality studies with long-term follow up are warranted to give more convincing evidence.

Anatomic total shoulder arthroplasty with an inlay glenoid component: clinical outcomes and return to activity

BACKGROUND

Biomechanical studies show that inlay glenoid components in total shoulder arthroplasty (TSA) can reduce edge loading and opposite-edge lift-off forces with humeral translation compared with onlay glenoids. However, clinical data for these implants are lacking. We report clinical outcomes and return to activities after anatomic TSA with an inlay glenoid component and a stemless ovoid humeral head in an active, young patient population.

METHODS

A retrospective review of TSA with an inlay glenoid component and an ovoid humeral head component was performed for 27 shoulders. Patients were evaluated with patient-reported outcome measures, range of motion, and radiographs. Return to occupational and sporting activity, complications, and reoperations were analyzed.

RESULTS

A total of 27 shoulders were available for minimum 2-year follow-up. Age averaged 52.1 years, and 92.6% of shoulders were in male patients. The preoperative Walch grade was A1 or A2 in 15 shoulders (55%), B1 in 8 (30%), and B2 in 4 (15%). Patients showed significant improvements in patient-reported outcome measures, active forward flexion, and external rotation (P < .001) with no reoperations. At an average of 3.7 months, the rate of return to work was 92.6%, with 76.0% of those patients returning to their preoperative occupational demand level. At an average of 9.1 months, 75% of patients who responded to our custom survey returned to sport, with 50% achieving the same level or a higher level of sporting activity. Annual postoperative radiographs revealed no inlay component loosening.

CONCLUSION

Anatomic TSA with an inlay glenoid coupled with a stemless ovoid humeral head in an active population resulted in improved clinical outcomes, no reoperations or radiographic loosening, and a high rate of return to activity at shorter-term follow-up.

Partial Humeral Head Resurfacing for Avascular Necrosis

Large chondral lesions of the humeral head are often treated with total shoulder arthroplasty, but this may not be an ideal option for young, active patients. Humeral head resurfacing is another option, which better preserves the native biomechanics. This article and the accompanying video present the surgical technique of partial humeral head resurfacing, which further preserves the remaining healthy cartilage. It is described for a chondral lesion due to avascular necrosis, but the method has been successfully used to treat chondral lesions from a broad range of causes.

Total shoulder arthroplasty with nonspherical humeral head and inlay glenoid replacement: clinical results comparing concentric and nonconcentric glenoid stages in primary shoulder arthritis

Background

Glenoid morphology can influence the outcomes of total shoulder arthroplasty. This study examines the results of a new technique according to preoperative glenoid staging. We hypothesized that there would be no statistically significant difference in outcomes between Levine concentric (Walch A) and Levine nonconcentric (Walch B) glenoids treated for primary glenohumeral arthritis using nonspherical humeral head and inlay glenoid replacement.

Methods

This retrospective case series included 31 shoulders in 29 patients (25 male, 4 female), with an average age of 58.5 years. Outcomes included the Penn Shoulder Score (PSS), visual analog scale for pain (VAS-Pain), range of motion, radiographic analysis, and complications. Inclusion criteria were primary glenohumeral arthritis, intact rotator cuff, and no prior open shoulder surgeries.

Results

Mean follow-up was 42.6 months (range, 24-74 months). The study included 7 concentric and 24 nonconcentric glenoids. Outcomes comparison showed no statistically significant differences in PSS domains including Pain (P = .92), Function (P = .98), Satisfaction (P = .89), and Total (P = .98); forward flexion (P = .78); external rotation (P = .64); and VAS-Pain (P = 0.12). At the last follow-up, the mean PSS Pain was 25.3/30, Function 52.7/60, Satisfaction 8.4/10, and Total 87.0/100. The mean forward flexion was 167.3°, external rotation 56.6°, and VAS-Pain 0.9. There were no signs of periprosthetic fracture, component loosening, osteolysis, and hardware failure, and no revisions or 90-day rehospitalizations were required. One patient was prophylactically treated with oral antibiotics for a history of prior infection and 1 patient required a later open biceps tenodesis after a traumatic proximal biceps rupture postoperatively.

Conclusion

Nonspherical shoulder arthroplasty with inlay glenoid replacement demonstrated excellent clinical benefits for both concentric and nonconcentric glenoids. The technique appears to be a promising option for glenohumeral arthritis even in the presence of posterior glenoid erosion.

Preoperative Comorbidities and Postoperative Complications Do Not Influence Patient-Reported Satisfaction Following Humeral Head Resurfacing: Mid- to Long-term Follow-up of 106 Patients

Background

Humeral head resurfacing (HHR) has emerged as an alternative treatment for glenohumeral osteoarthritis. We investigated the outcomes of HHR using validated patient-reported outcome (PRO) measures.

Methods

A retrospective review was performed on 213 patients who underwent HHR. A PRO follow-up was performed by administering a questionnaire including the American Shoulder and Elbow Society (ASES) score, Brophy activity survey, short form of the Disabilities of the Arm, Shoulder and Hand (quickDASH) survey, and general shoulder function. PRO scores were stratified by comorbidities and complications.

Results

Survey responses were received from 106 patients (51%), with a mean follow-up of 5.6 ± 1.8 years (range: 9 months to 6.1 years). Preoperative comorbidities were associated with significantly higher quickDASH scores. Postoperative complications were associated with significantly higher rates of current pain, higher visual analog scale scores, night pain, lower subjective shoulder values, and lower ASES pain and total scores. No differences in patient satisfaction were identified between the cohorts with and without preoperative comorbidities and between the cohorts with and without postoperative complications.

Conclusion

In our cross-sectional analysis of mid- to long-term outcomes following HHR, preoperative comorbidities, or postoperative complications had no impact on patient-perceived postoperative satisfaction or most PROs. HHR is clinically viable in a wide variety of patients. Future work is necessary to compare the efficacy of HHR compared with more traditional total shoulder arthroplasty and stemmed hemiarthroplasty regarding long-term outcomes and appropriate indications.

Results of partial resurfacing of humeral head in patients with avascular necrosis

OBJECTIVE

The aim of this study was to report the short-term results and complications of partial humeral head resurfacing (HemiCup^®) in patients treated by avascular necrosis.

MATERIAL AND METHODS

Between 2010 and 2014, 9 patients who underwent partial resurfacing of humeral head were evaluated. All the patients were treated by avascular necrosis. The mean follow-up was 44 months (minimum 24 months). The average age was 47 years (range 32-57 years). The patients were evaluated clinically and radiologically. Complications were reported.

RESULTS

The patients had a significant improvement in functional scores and mobility between the pre-operative and last follow-up control. The Constant score improved from 35 to 79 points (P<.001), ASES score improved from 31 to 76 points (P<.001), forward flexion and external rotation improved from 101 to 150° (P<.001), and from 24 to 45° (P<.001), respectively. One patient presented symptomatic glenoid wear during follow-up, requiring revision surgery.

CONCLUSION

In our patients treated by avascular necrosis, the partial resurfacing of humeral head (HemiCup^®) demonstrated a significant improvement in functional scores and mobility with an average follow-up of 44 months.

Imaging of Shoulder Arthroplasties

OBJECTIVE

In this article, we review the preoperative imaging features used for planning shoulder arthroplasty as well as review the various shoulder arthroplasty component types, discussing the expected normal imaging features and specific complications to look for with each.

CONCLUSION

Given the increasing use of shoulder arthroplasty, it is important to understand the imaging features of the various shoulder arthroplasty complications.

Effects of Prosthetic Mismatch and Subscapularis Tear on Glenohumeral Contact Patterns in Total Shoulder Arthroplasty: A Numerical Musculoskeletal Analysis

Prosthetic components' mismatch and subscapularis (SC) tear are determining factors for glenoid failure complication in nonconforming total shoulder arthroplasty (NC-TSA). Risk factors are linked to glenoid prosthetic loading. However, the mechanisms underlying the clinical observations remain unclear. This study assessed the combined impact of mismatch and subscapularis tear on glenoid loading. It was assumed that adequate glenoid loading was associated with minimal, but non-null, humeral head translations and contact pressure, as well as with maximal glenoid contact area, and that the center of pressure (COP) on the glenoid would have a centered displacement pattern. A numerical model was used to achieve two objectives. The first was to verify whether an optimum mismatch existed, for which failure risk would be minimal. The second was to explore the effect of subscapularis tear on the position of applied forces on the glenoid. A shoulder AnyBody musculoskeletal model was adapted to the arthroplasty context by introducing humeral head translations and contact between implants. Ten simulations were computed to compare combinations of varying mismatches (1.4 mm, 3.4 mm, 6.4 mm, 8.6 mm, and 9 mm) with two shoulder conditions (intact-muscle or subscapularis tear). Humeral head translations, center-of-pressure, contact area, contact pressure, and glenohumeral joint contact forces were numerically estimated. Mismatches between 3.4 mm and 6.4 mm were associated with the most minimal humeral translations and contact pressure, as well as with maximal contact area. Center of pressure displacement pattern differed according to shoulder condition, with an outward anterior tendency in presence of tear.

Clinical and radiological results 7 years after Copeland shoulder resurfacing arthroplasty in patients with primary glenohumeral osteoarthritis: an independent multicentre retrospective study

PURPOSE

The aim of this multicentre cohort study was to evaluate the midterm outcomes and survival after cementless stemless resurfacing arthroplasty (CSRA) in a series of 33 shoulders in 27 patients with primary osteoarthritis.

METHODS

Clinical outcome assessment included: Constant-Murley score (CMS); Simple Shoulder Test (SST); Disability of Arm, Shoulder, Hand (DASH); EuroQol-5D (EQ-5D) utility scores; Numerous Rating Scale (NRS) for pain. Radiographs were assessed by two independent observers for oversizing, radiolucency, glenohumeral subluxation, glenoid erosion and subsidence. Correlations between the clinical and radiological outcomes were calculated. Complications were registered, and revision and survival rates were calculated.

RESULTS

Mean age at time of surgery and mean follow-up time were, respectively, 67.7 (range 50.2-85.1) and 7.2 years (range 5.7-9.3 years). Means (SD) for CMS, age- and gender-adjusted CMS, SST, DASH and EQ-5D utility scores were: 56.4 (20.2), 76.5 (25.0), 54.0 (29.8), 37.6 (23.3) and 0.8 (0.1), respectively. NRS for pain was 2.0 and 3.8, respectively, in rest and during activities. Radiographic assessment of the CSRAs showed oversizing in 54.5%; radiolucency in 18.2%; superior glenohumeral subluxation in 33.3%; glenoid erosion in 45.5%; and subsidence in 3.0%. Perioperative complications did not occur. Revision surgery was performed in one patient (3.0%).

CONCLUSION

For primary osteoarthritis, the CSRA showed good clinical but poor radiological outcomes at midterm follow-up.

A comparison of onlay versus inlay glenoid component loosening in total shoulder arthroplasty

BACKGROUND

Glenoid component loosening is common in total shoulder arthroplasty (TSA), often resulting from the mechanical interaction of glenohumeral components. This cadaveric study was performed to evaluate and to compare commercially available onlay and inlay glenoid prosthetic designs with respect to loading characteristics and loosening.

METHODS

Sixteen prescreened cadaveric shoulders (8 matched pairs) underwent either onlay or inlay TSA. We created a custom glenohumeral loading model and used cycles of 5 mm anterior-posterior humeral translation to simulate a rocking-horse loosening mechanism for all testing. Articular TekScan measurements were performed with 9.1 kg (88.9 N) of glenohumeral compression before and after TSA. Fatigue testing was performed with 34.0 kg (333.6 N) of glenohumeral compression using high-definition video to document gross glenoid loosening. Testing ended with gross loosening or a maximum of 4000 cycles. Mean contact area, pressure, and joint reaction force were used to compare the 2 glenoid designs.

RESULTS

In both implant types, contact area decreased and pressure increased after TSA (P < .0001). Force increased at the onlay component edge only (P = .0012) compared with native glenoid testing. Force was greater in the onlay vs. the inlay implants (P < .0001). During fatigue testing, all onlay glenoid components exhibited gross loosening at a mean of 1126 cycles (range, 749-1838), whereas none of the inlay glenoid components exhibited gross loosening (P < .0001).

CONCLUSION

The inlay glenoid implant exhibited biomechanical characteristics favoring stability and decreased loosening compared with the onlay glenoid implant in this cadaveric model.

Comparative study of total shoulder arthroplasty versus total shoulder surface replacement for glenohumeral osteoarthritis with minimum 2-year follow-up

BACKGROUND

Compared with total shoulder arthroplasty (TSA), total shoulder surface replacement (TSSR) may offer the advantage of preservation of bone stock and shorter surgical time, possibly at the expense of glenoid component positioning and increasing lateral glenohumeral offset. We hypothesized that in patients treated for osteoarthritis with a sufficient rotator cuff, TSA and TSSR patients have comparable functional outcome, glenoid component version, and lateral glenohumeral offset.

METHODS

We conducted a retrospective cohort study with a minimum of 2 years of follow-up. Patients in the TSA and TSSR groups received a cemented, curved, keeled, all-poly glenoid component. A cemented anatomical humeral stem was used in TSA. TSSR involved a humeral surface replacement (all components from Tornier Inc., St Ismier, France). Patients were assessed for functional outcome. Radiographs were assessed for radiolucent lines. Glenoid component position and lateral glenohumeral offset were assessed using computed tomography images.

RESULTS

After 29 and 34 months of mean follow-up, respectively, TSA (n = 29) and TSSR (n = 20) groups showed similar median adjusted Constant Scores (84% vs. 88%), Oxford Shoulder Scores (44 vs. 44), Disabilities of the Arm, Shoulder and Hand scores (22 vs. 15), and Dutch Simple Shoulder Test scores (10 vs. 11). Glenoid components showed similar radiolucent line counts (median, 0 vs. 0), similar anteversion angles (mean, 0° vs. 2°), and similar preoperative to postoperative increases in lateral glenohumeral offset (mean, 4 vs. 5 mm). One intraoperative glenoid fracture occurred in the TSSR group.

CONCLUSION

Short-term functional and radiographic outcomes were comparable for TSA and TSSR.

Biomechanical benefits of anterior offsetting of humeral head component in posteriorly unstable total shoulder arthroplasty: A cadaveric study

Restoration of joint stability during total shoulder arthroplasty can be challenging in the face of severe glenoid retroversion. A novel technique of humeral head component anterior-offsetting has been proposed to address posterior instability. We evaluated the biomechanical benefits of this technique in cadaveric specimens. Total shoulder arthroplasty was performed in 14 cadaveric shoulders from 7 donors. Complementary shoulders were assigned to either 10° or 20° glenoid retroversion, with retroversion created by eccentric reaming. Two humeral head component offset positions were tested in each specimen: The anatomic (posterior) and anterior (reverse). With loads applied to the rotator cuff and deltoid, joint contact pressures and the force and energy required for posterior humeral head translation were measured. The force and energy required to displace the humeral head posteriorly increased significantly with the anterior offset position compared to the anatomic offset position. The joint contact pressures were significantly shifted anteriorly, and the joint contact area significantly increased with the anterior offset position. Anterior offsetting of the humeral head component increased the resistance to posterior humeral head translation, shifted joint contact pressures anteriorly, and increased joint contact area, thus, potentially increasing the joint stability in total shoulder arthroplasty with simulated glenoid retroversion.

Bone repair with skeletal stem cells: rationale, progress to date and clinical application

Bone marrow (BM) contains stem cells for both hematopoietic and nonhematopoietic lineages. Hematopoietic stem cells enable hematopoiesis to occur in a controlled manner in order to accurately compensate for the loss of short- as well as long-lived mature blood cells. The physiological role of nonhematopoietic BM stem cells, often referred to as multipotential stromal cells or skeletal stem cells (SSCs), is less understood. According to an authoritative current opinion, the main function of SSCs is to give rise to cartilage, bone, marrow fat and hematopoiesis-supportive stroma, in a specific sequence during embryonic and postnatal development. This review outlines recent advances in the understanding of origins and homeostatic functions of SSCs in vivo and highlights current and future SSC-based treatments for skeletal and joint disorders.

Return to Sports and Physical Activities After Primary Partial Arthrodesis for Lisfranc Injuries in Young Patients

BACKGROUND

Research regarding outcomes in sports and physical activities after primary partial arthrodesis for Lisfranc injuries has been sparse. The purposes of this study were to assess various sports and physical activities in young patients following primary partial arthrodesis for Lisfranc injuries and to compare these with clinical outcomes.

METHODS

Patients who underwent primary partial arthrodesis for a Lisfranc injury were identified by a retrospective registry review. Thirty-eight of 46 eligible patients (83%) responded for follow-up at a mean of 5.2 (range, 1.0 to 9.3) years with a mean age at surgery of 31.8 (range, 16.8 to 50.3) years. Physical activity participation was assessed with a new sports-specific, patient-administered questionnaire. Clinical outcomes were assessed with the Foot and Ankle Outcome Score (FAOS).

RESULTS

Patients participated in 29 different and 155 total physical activities preoperatively, and 27 different and 145 total physical activities postoperatively. Preoperatively, 47.1% were high impact, and postoperatively, 44.8% were high impact. The most common activities were walking, bicycling, running, and weightlifting. Compared to preoperatively, difficulty was the same in 66% and increased in 34% of physical activities. Participation levels were improved in 11%, the same in 64%, and impaired in 25% of physical activities. Patients spent on average 4.2 (range, 0.0 to 19.8) hours per week exercising postoperatively. In regard to return to physical activity, 97% of respondents were satisfied with their operative outcome. Mean postoperative FAOS subscores were significantly worse for patients who had increased physical activity difficulty.

CONCLUSION

Most patients were able to return to their previous physical activities following primary partial arthrodesis for a Lisfranc injury, many of which were high-impact. However, the decreased participation or increase in difficulty of some activities suggests that some patients experienced postoperative limitations in exercise. Future studies could compare sports outcomes between primary partial arthrodesis and open reduction internal fixation for Lisfranc injuries.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Long-term follow-up of the Copeland mark III shoulder resurfacing hemi-arthroplasty

BACKGROUND

Shoulder humeral resurfacing is being performed in increasing numbers. We report the long-term outcome of patients with the Copeland mark III humeral resurfacing hemi-arthroplasty.

METHODS

Ninety-five shoulder hemi-arthroplasties were performed in 85 patients, from 1994 to 2003. Oxford Shoulder Score (OSS) and short form 12 (SF-12) questionnaires were administered.

RESULTS

At 12-year follow-up, 49 patients were alive. The OSS was 35.2 and SF-12 score was 83. There were 3 revision operations and 95% survivorship at 18 years.

CONCLUSION

This prosthesis has a low revision rate with few post-operative complications and good patient-reported outcome in an elderly population.

Adaptation of the AnyBody™ Musculoskeletal Shoulder Model to the Nonconforming Total Shoulder Arthroplasty Context

Current musculoskeletal inverse dynamics shoulder models have two limitations to use in the context of nonconforming total shoulder arthroplasty (NC-TSA). First, the ball and socket glenohumeral (GH) joint simplification avoids any humeral head translations. Second, there is no contact at the GH joint to compute the contact area and the center of pressure (COP) between the two components of NC-TSA. In this paper, we adapted the AnyBody™ shoulder model by introducing humeral head translations and contact between the two components of an NC-TSA. Abduction in the scapular plane was considered. The main objective of this study was to adapt the AnyBody™ shoulder model to a NC-TSA context and to compare the results of our model (translations, COP, contact area, GH joint reaction forces (GH-JRFs), and muscular forces) with previous numerical, experimental, and clinical studies. Humeral head translations and contact were successfully introduced in our adapted shoulder model with strong support for our findings by previous studies.

Arthroscopic partial shoulder resurfacing

PURPOSE

The purpose of this study was to report patients' clinical and subjective outcomes 2 years after arthroscopic-assisted partial resurfacing of the humeral head.

METHODS

In this prospective case series, 11 patients (4 females, 7 males; median age, 59 years; range 47-72) underwent arthroscopic-assisted partial shoulder resurfacing between April 2010 and March 2011. Clinical conditions and subjective assessments were evaluated before surgery and at 6 weeks, 3 and 6 months, and then annually after surgery using the Constant score (CS), active range of motion (ROM), the visual analogue scale (VAS) for pain, the American Shoulder and Elbow Surgeons scale (ASES), and the subjective shoulder value (SSV). Radiological outcomes and major complications were monitored.

RESULTS

The mean CS improved significantly from 54.6 ± 13.6 preoperatively to 72.9 ± 17.2 points 6 weeks postoperatively (P = 0.009). At the 2-year follow-up, the mean CS had further increased to 86.5 ± 14.3 points (P < 0.001). Trends towards increasing ROMs were detected. VAS, ASES, and SSV significantly improved from baseline to the first follow-up and maintained improvement after 2 years. One patient required revision surgery owing to a technical failure and two patients because of rapidly progressive osteoarthritis. Ten of 11 patients (91 %) claimed that they would undergo arthroscopic partial shoulder resurfacing again.

CONCLUSION

Arthroscopic-assisted partial humeral head resurfacing, which has the advantages of bone stock preservation and the maintenance of an intact subscapularis tendon, allowed immediate postoperative mobilization and provided significant improvements in subjective outcomes, especially for pain relief in active patients without severe glenoid cartilage wear.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Primary partial humeral head resurfacing: outcomes with the HemiCAP implant

BACKGROUND

Humeral head defects such as degenerative disease or avascular necrosis are often treated with stemmed hemiarthroplasty or total shoulder arthroplasty. Despite its historical and clinical significance, stemmed humeral head replacement poses inherent technical challenges to placing spherical implants at the anatomically correct head height, version, and neck-shaft angle.

PURPOSE

The aim of this study was to assess humeral head inlay arthroplasty as a joint-preserving alternative that maintains the individual head-neck-shaft anatomy. Humeral head inlay arthroplasty also allows intraoperative surface mapping and placement of a contoured articular component that is matched to the patient's defect size, location, and individual surface geometry.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This retrospective case series included 19 patients (20 shoulders), with an average age of 48.9 years (range, 32-58 years; 16 men, 3 women). Preoperative diagnoses were osteoarthritis in 16 shoulders and osteonecrosis in 4 shoulders. Pre- and postoperative evaluations included physical examination, radiographic assessment, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, the Simple Shoulder Test, a pain visual analog scale, and patient satisfaction rating.

RESULTS

The mean follow-up period was 32.7 months (range, 17-66 months). The mean American Shoulder and Elbow Surgeons score improved from 24.1 to 78.8, mean Simple Shoulder Test score from 3.95 to 9.3, mean visual analog scale score from 8.2 to 2.1, mean forward flexion from 100° to 129°, and mean external rotation from 23° to 43° (P < .001 for all). Radiographic follow-up showed no evidence of periprosthetic fracture, component loosening, osteolysis, or device failure. Patient shoulder self-assessment was 90% poor before surgery and improved to 75% good to excellent at last follow-up; 20% of patients self-rated as somewhat good to somewhat poor, and 5% self-rated as poor. Ninety percent of patients were satisfied with the choice of the procedure. Three patients had postoperative complications unrelated to the implants, including a partial rotator cuff tear treated with physical therapy, preexisting glenoid wear treated with arthroscopic debridement and microfracture, and infection complicated by subscapularis rupture requiring several subsequent surgical procedures but with retention of the implant.

CONCLUSION

Humeral head inlay arthroplasty is effective in providing pain relief, functional improvement, and patient satisfaction. Rather than delaying shoulder arthroplasty to end-stage osteoarthritis, humeral head inlay arthroplasty is a promising new direction in primary shoulder arthroplasty for younger and active patients with earlier stage disease.

Radiographic assessment of prosthetic humeral head size after anatomic shoulder arthroplasty

BACKGROUND

Restoring the premorbid proximal humeral anatomy during shoulder arthroplasty is critical yet can be difficult because of the deformity of the arthritic head. The purpose of this study was to measure the variation between surgeons and between types of prosthetics in reproducing the anatomic center of rotation (COR) of the humeral head after anatomic shoulder arthroplasty.

METHODS

The anteroposterior radiographs of 125 stemmed and 43 resurfacing shoulder arthroplasties, performed by 5 experienced surgeons, were analyzed. All patients had primary replacement for treatment of end-stage glenohumeral arthritis. A best-fit circle to preserved nonarticular humeral landmarks was used to define the difference between the anatomic COR and the prosthetic COR. A difference in COR of >3.0 mm was considered clinically significant and analyzed for the cause of this deviation.

RESULTS

The average deviation of the postoperative COR from the anatomic COR was 2.5 ± 1.6 mm for stemmed cases and 3.8 ± 2.1 mm for resurfacings. Thirty-nine stemmed cases (31.2%) and 28 resurfacings (65.1%) were beyond 3.0 mm of deviation and regarded as outliers. The majority of the stemmed outliers and all resurfacing outliers were overstuffed. An improper humeral head size selection and inadequate reaming were the main reasons for the deviation in stemmed and resurfacing outliers, respectively.

CONCLUSION

A large percentage of shoulder replacements demonstrated significant deviations from an anatomic reconstruction. Resurfacing arthroplasty exhibited significantly greater deviations compared with stemmed arthroplasty (P < .001), indicating that surgeons have more difficulty in restoring the anatomy with resurfacings. Further studies are needed to assess the clinical impact of these deviations.

Glenohumeral pressure with surface replacement arthroplasty versus hemiarthroplasty

It is not known whether significant differences in the glenohumeral center of pressure and contact pressure exist between surface replacement arthroplasty and hemiarthroplasty compared with the native joint. Twelve fresh-frozen cadaveric shoulders were dissected free of soft tissue, and the joint capsule was removed. The scapula was potted with the glenoid parallel to the ground. A pressure-sensitive sensor was placed in the glenohumeral joint, and each specimen was tested in sequence: intact, surface replacement, and hemiarthroplasty. Loading was done with a 440-N compression load at 0.5 Hz with the shoulder in 4 different positions. The center of pressure and contact pressure were measured at each position. The glenohumeral contact pressure with surface replacement was not different from intact pressure in 2 arm positions. Pressure with hemiarthroplasty was significantly different compared with the intact shoulder at all 4 arm positions and compared with the surface replacement group at 2 arm positions (P≤.05). Change in the anterior-posterior center of pressure from intact was significantly smaller with surface replacement compared with hemiarthroplasty with the humerus at 0° flexion/0° abduction and at 0° flexion/90° abduction (1.11±0.89 mm vs 2.38±1.62 mm, P=.02, and 0.68±0.50 mm vs 2.37±2.0 mm, P=.01, respectively). Change in the superior-inferior center of pressure was significantly smaller with surface replacement vs hemiarthroplasty at 0° flexion/0° abduction and at 90° flexion/90° abduction (0.98±1.16 mm vs 2.33±1.38 mm, P=.02, and 1.50±1.28 mm vs 2.90±1.92 mm, P=.04, respectively). Compared with hemiarthroplasty, surface replacement arthroplasty more closely replicated the contact pressure and center of pressure in the intact glenohumeral joint.

Stemmed hemiarthroplasty versus resurfacing in primary shoulder osteoarthritis: a single-center retrospective series of 78 patients

INTRODUCTION

Resurfacing shoulder arthroplasty is proposed in primary osteoarthritis of the shoulder. The present study compared resurfacing versus 3rd generation stemmed hemiarthroplasty in terms of survival, functional results and implant positioning effects.

MATERIALS AND METHODS

Seventy eight patients underwent arthroplasty for primary osteoarthritis of the shoulder: 41 by resurfacing and 37 by stemmed hemiarthroplasty. The two populations were comparable on all baseline variables. Minimum follow-up was 2 years. The principal assessment criterion was survivorship with surgical revision as end-point. Secondary criteria were functional results on Constant, quick-DASH, Neer and SSV scores, and implant positioning effects assessed on radiology.

RESULTS

At a mean 44 months' follow-up (range, 24-118 months), there were no significant differences in functional scores. Radiologic analysis found greater varus positioning and lateral offset of the humeral head in resurfacing compared with stemmed hemiarthroplasty (128° vs 138°, P<0.01; 6.5 ± 2 vs 4.6 ± 1.6mm, P<0.01). Survivorship without revision was significantly poorer in resurfacing, with 4 revision procedures for glenoid wear (9.8%), versus none in hemiarthroplasty (P=0.02). There was no correlation between humeral head size, positioning or lateral offset and revision.

CONCLUSION

Revision-free survival was significantly lower in resurfacing than in hemiarthroplasty. Greater humeral head size may increase lateral offset, accelerating glenoid wear. Down-sizing the humeral head in resurfacing procedures might limit these complications.

LEVEL OF EVIDENCE

Level III; case-control study.

Resurfacing hemiarthroplasty compared to stemmed hemiarthroplasty for glenohumeral osteoarthritis: a randomised clinical trial

PURPOSE

The aim of this study was to conduct a randomised, clinical trial comparing stemmed hemiarthroplasty and resurfacing hemiarthroplasty in the treatment of glenohumeral osteoarthritis.

METHODS

A total of 40 shoulders (35 patients) were randomised to stemmed hemiarthroplasty or resurfacing hemiarthroplasty and evaluated three and 12 months postoperatively using the Constant-Murley score (CMS) and Western Ontario Osteoarthritis of the Shoulder (WOOS) index.

RESULTS

There were no statistically significant differences in age, gender or pre-operative scores except for WOOS at baseline. Two patients were lost to follow-up. Significant improvements in CMS and WOOS were observed at one year after both arthroplasty designs. At one year, the mean CMS was 48.9 (range 6-80) after resurfacing hemiarthroplasty and 59.1 (range 0-88) after stemmed hemiarthroplasty {mean difference 10.2 [95 % confidence interval (CI) -3.3 to 23.6], P = 0.14}. The mean WOOS was 59.2 (range 5.2-100.0) and 79.4 (range 12.8-98.6), respectively [mean difference 20.2 (95 % CI 3.4-36.9), P = 0.02]. No major complications occurred and there were no revisions.

CONCLUSIONS

The effects of resurfacing hemiarthroplasty tended to be inferior to those of stemmed hemiarthroplasty. It is unclear whether this reflects a real difference in effect or baseline differences due to the limited number of randomised patients. We suggest there is a need for a larger, more definitive trial.

Outcome, revision rate and indication for revision following resurfacing hemiarthroplasty for osteoarthritis of the shoulder: 837 operations reported to the Danish Shoulder Arthroplasty Registry

In this study, we evaluated patient-reported outcomes, the rate of revision and the indications for revision following resurfacing hemiarthroplasty of the shoulder in patients with osteoarthritis. All patients with osteoarthritis who underwent primary resurfacing hemiarthroplasty and reported to the Danish Shoulder Arthroplasty Registry (DSR), between January 2006 and December 2010 were included. There were 772 patients (837 arthroplasties) in the study. The Western Ontario Osteoarthritis of the Shoulder (WOOS) index was used to evaluate patient-reported outcome 12 months (10 to 14) post-operatively. The rates of revision were calculated from the revisions reported to the DSR up to December 2011 and by checking deaths with the Danish National Register of Persons. A complete questionnaire was returned by 688 patients (82.2%). The mean WOOS was 67 (0 to 100). A total of 63 hemiarthroplasties (7.5%) required revision; the cumulative five-year rate of revision was 9.9%. Patients aged < 55 years had a statistically significant inferior WOOS score, which exceeded the minimal clinically important difference, compared with older patients (mean difference 14.2 (8.8; 95% CI 19.6; p < 0.001), but with no increased risk of revision. There was no significant difference in the mean WOOS or the risk of revision between designs of resurfacing hemiarthroplasty.

Outcome and risk of revision following shoulder replacement in patients with glenohumeral osteoarthritis

This thesis includes four studies focusing on the functional outcome, shoulder-specific quality of life and risk of revision following shoulder replacement in patients with glenohumeral osteoarthritis without symptomatic rotator cuff pathology. The Danish version of WOOS, translated according to international standardized guidelines, had substantial psychometric properties comparable to the original version. It is recommendable to use WOOS in the evaluation of patients with glenohumeral osteoarthritis treated with shoulder replacement. Data from DSR showed that the shoulder specific quality of life following total shoulder arthroplasty was superior to that of hemiarthroplasty (resurfacing hemiarthroplasty and stemmed hemiarthroplasty). The difference between stemmed hemiarthroplasty and resurfacing hemiarthroplasty was small and did not exceed the minimal clinically important difference. The revision rate following resurfacing hemiarthroplasty was surprisingly high compared with previous reports but there were no statistical significant differences in revision rate between arthroplasty designs. The shoulder specific quality of life and revision rate in patients under the age of 55 was worrying. The use of resurfacing hemiarthroplasty has relied on the results from case series only. The efficacy in the treatment of glenohumeral osteoarthritis has been promising but the CMS found in the randomized clinical trial indicate that the functional outcome may be inferior to that of stemmed hemiarthroplasty and less favourable than previously reported. However, the limited number of patients may have influenced the results and a larger definitive RCT is needed.Shoulder replacement is relevant and effective in the treatment of glenohumeral osteoarthritis; however, resurfacing hemiarthroplasty was associated with a poorer outcome and a higher risk of revision than previously assumed especially in patients under the age of 55. Based on data from this thesis, and based on existing knowledge, it seems like total shoulder arthroplasty should be preferred in the treatment of glenohumeral osteoarthritis. Shoulder replacement is rarely indicated in younger patients where other treatment options (e.g., physiotherapy; intraarticular injections of hyaluronate; and joint preserving surgery) should be considered until the efficacy of shoulder replacement has been more thoroughly documented.

Patient-reported outcome and risk of revision after shoulder replacement for osteoarthritis. 1,209 cases from the Danish Shoulder Arthroplasty Registry, 2006-2010

PURPOSE

We used patient-reported outcome and risk of revision to compare hemiarthroplasty (HA) with total shoulder arthroplasty (TSA) and stemmed hemiarthroplasty (SHA) with resurfacing hemiarthroplasty (RHA) in patients with glenohumeral osteoarthritis.

PATIENTS AND METHODS

We included all patients reported to the Danish Shoulder Arthroplasty Registry (DSR) between January 2006 and December 2010. 1,209 arthroplasties in 1,109 patients were eligible. Western Ontario Osteoarthritis of the Shoulder index (WOOS) was used to evaluate patient-reported outcome 1 year postoperatively. For simplicity of presentation, the raw scores were converted to a percentage of the maximum score. Revision rates were calculated by checking reported revisions to the DSR until December 2011. WOOS and risk of revision were adjusted for age, sex, previous surgery, and type of osteoarthritis.

RESULTS

There were 113 TSAs and 1096 HAs (837 RHAs and 259 SHAs). Patients treated with TSA generally had a better WOOS, exceeding the predefined minimal clinically important difference, at 1 year (mean difference 10, p < 0.001). RHA had a better WOOS than SHA (mean difference 5, p = 0.02), but the difference did not exceed the minimal clinically important difference. There were no statistically significant differences in revision rate or in adjusted risk of revision between any of the groups.

INTERPRETATION

Our results are in accordance with the results from other national shoulder registries and the results published in systematic reviews favoring TSA in the treatment of glenohumeral osteoarthritis. Nonetheless, this registry study had certain limitations and the results should be interpreted carefully.

Surface Replacement Arthroplasty of the Humeral Head in Young, Active Patients: Midterm Results

Background:

The treatment of glenohumeral arthritis in young, active patients remains controversial. Standard total shoulder arthroplasty in this patient group has not obtained the same satisfaction rate as in older patients. One surgical option that has emerged is humeral resurfacing.

Hypothesis:

Humeral head surface replacement arthroplasty (SRA) would provide satisfactory clinical outcomes in active patients, allowing them to maintain their normal lifestyle without activity restrictions.

Study Design:

Case series; Level of evidence, 4.

Methods:

From 2004 to 2007, all consecutive surface replacement arthroplasties of the humerus performed at the authors’ institution were identified and retrospectively reviewed, and 118 patients who underwent SRA during this time were identified. This study included patients younger than 60 years who wished to maintain an active lifestyle; 52 of the 118 patients met the inclusion criteria. University of California at Los Angeles (UCLA) shoulder scores and subjective shoulder value (SSV) scores were used to measure clinical outcomes at an average follow-up of 6 years (range, 4-8 years). Of the 52 patients meeting the inclusion criteria, 48 were contacted and examined for the study, with 4 patients lost to follow-up.

Results:

The mean postoperative UCLA score was 28.03, with 1 patient requiring revision because of pain and glenoid wear. The mean SSV was 92% (range, 0%-100%), with 3 patients restricting their activity because of the shoulder. Forty-seven of the 48 contacted patients stated that, given the option, they would have the same surgery again. One patient required revision surgery because of pain.

Conclusion:

Surface replacement arthroplasty provided reasonable results in patients younger than 60 years with high activity demands with a low rate of revision at midterm follow-up.

Durability of partial humeral head resurfacing

BACKGROUND

Partial humeral head resurfacing arthroplasty uses a stemless device, which conserves bone and restores normal anatomy. We hypothesized that this does not offer a reasonable alternative to full resurfacing or total shoulder arthroplasty.

METHODS

We performed a retrospective study of 39 shoulders with focal chondral defects of the humeral head treated with partial resurfacing arthroplasty. A minimum of 2 years' follow-up was reported, unless failure and operative intervention superseded this duration. The mean follow-up period was 51.3 months. The mean age was 45.6 years (range, 27-76 years). Preoperative and postoperative evaluation included history, physical examination, radiographs, and clinical scoring with the American Shoulder and Elbow Surgeons Shoulder Score Index and Subjective Shoulder Value.

RESULTS

Of the 39 shoulders, 25 (64.1%) showed functional improvement and decreased pain. Significant mean improvements were observed in forward flexion (121° to 152°, P = .002), external rotation (37° to 58°, P = .0003), mean Subjective Shoulder Value (31% to 74%, P < .0001), and ASES score (29 to 70, P < .0001). However, at a mean of 26.6 months' follow-up, the failure group included 6 patients (15.3%) who underwent revision and another 4 (10.2%) who were recommended to undergo revision. Patients with no prior or concomitant procedures were rare (n = 5) but had the most reliable outcomes with partial resurfacing, with no failures in that group. Of the 24 patients with prior procedures, 5 had undergone revision, and the clinical outcome scores for the remaining patients were consistently lower than those seen in patients without prior procedures.

CONCLUSION

Concomitant pathology and prior or concomitant surgical procedures potentially impair the outcome of the resurfacing procedure and could be a contraindication. Long-term success remains guarded with this treatment modality, especially in patients whose chondral injury is not an isolated finding.

The use of shoulder hemiarthroplasty and humeral head resurfacing: a review of current concepts

Since Neer's early work in the 1950s shoulder arthroplasty has evolved as a treatment option for various glenohumeral joint disorders. Both hemiarthroplasty and total shoulder prostheses have associated problems. This has led to further work with regards to potential resurfacing, with the aim of accurately restoring native proximal humeral anatomy while preserving bone stock for later procedures if required. Hemiarthroplasty remains a valuable treatment option in the low demand patient or in the trauma setting. Additional work is required to further define the role of humeral resurfacing, with the potential for it to become the gold standard for younger patients with isolated humeral head arthritis.

Thermal damage during humeral reaming in total shoulder resurfacing

INTRODUCTION

Total shoulder resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics. This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR.

PATIENTS AND METHODS

This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated.

RESULTS

Synthes (Epoca) instruments generated average temperatures of 40.7°C (SD 0.9°C) in the rheumatoid group and 56.5°C (SD 0.87°C) in the osteoarthritis group (P = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°C (SD 1.2°C). Saw bone analysis generated temperatures of 58.2°C (SD 0.79°C) in the Synthes (Epoca) 59.9°C (SD 0.81°C) in Biomet (Copeland) and 58.4°C (SD 0.88°C) in the Depuy Conservative Anatomic Prosthesis (CAP) reamers (P = 0.12).

CONCLUSION

Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels and should be performed regularly during this step in TSR.

Resurfacing humeral prosthesis: do we really reconstruct the anatomy?

BACKGROUND

The goal of a resurfacing shoulder arthroplasty is to reproduce the individual's anatomy while preserving the bone stock of the humeral head. This study investigated the hypothesis that resurfacing the humeral prosthesis restores normal glenohumeral relationships and correlates with the final clinical results.

MATERIALS AND METHODS

A resurfacing shoulder implant was performed in 61 patients (64 shoulders). Indications were primary osteoarthritis in 26, secondary osteoarthritis in 21, avascular necrosis in 4, rheumatoid arthritis in 4, dysplasia in 4, and for others indications in 5.

RESULTS

At an average of 36 months (range, 24-65) of follow-up , the Constant score reached 68 points and the Quick-Disabilities of Arm, Shoulder and Hand score reached 28 points. Preoperative and postoperative radiographic analysis showed a decrease of the humeral head diameter (51 ± 5 vs 48 ± 5 mm) and of the height of the humeral head (21 ± 4 vs 19 ± 2 mm), without modification of the radius of curvature or the height of the center of rotation. The medial humeral offset increased from 3.3 ± 3.5 to 6.4 ± 3 mm and the lateral offset from 6.8 ± 9 to 10.4 ± 9 mm. The implant was mainly in varus postoperatively compared with preoperative values (122° ± 11° vs 134° ± 7°). Postoperative radiographic analysis and at the last follow-up did not show any significant difference, except for the increase of the depth of the glenoid from 4.2 ± 1.4 to 4.9 ± 1.8 mm.

CONCLUSIONS

The resurfacing shoulder arthroplasty reproduces the normal anatomy and compensates glenohumeral wear. However, there was a tendency to position the prosthesis in varus because of technical imperfections. With follow-up, medialization of the humerus with glenoid wear was observed and was correlated in some patients with reappearance of pain.

Current concepts of shoulder arthroplasty for radiologists: Part 1--Epidemiology, history, preoperative imaging, and hemiarthroplasty

OBJECTIVE

The purpose of this article is to provide a review of indications for shoulder arthroplasty, describe preoperative imaging assessment, present new and modified designs of shoulder arthroplasty, illustrate normal and abnormal postoperative imaging findings, and review key radiographic measurements.

CONCLUSION

Knowledge of the physiologic purpose, orthopedic trends, imaging findings, and complications is important in assessing shoulder prostheses.