Surface and form alterations in retrieved shoulder hemiarthroplasty

B2 and B3 glenoid osteoarthirtis: outcomes of corrective and concentric (C2) reaming of the glenoid combined with pyrocarbon hemiarthroplasty

BACKGROUND

Posterior humeral subluxation (PHS) in B2 and B3 glenoid is a cause of asymmetric long-term stress on the glenoid and the potential reason for glenoid loosening in anatomic total shoulder arthroplasty and painful glenoid erosion in hemiarthroplasty with metallic heads. We hypothesized that corrective and concentric (C2) reaming of the glenoid associated with pyrocarbon hemiarthroplasty (HA-PYC) could improve the centering of the humeral head and decrease the risk of persistent painful glenoid erosion in young and active patients with B2 and B3 glenoid.

METHODS

Between 2014 and 2020, 41shoulders (in 35 patients, mean age of 57.9 years) underwent HA-PYC combined with C2 reaming for B2 (n = 30) or B3 (n = 11) osteoarthritis. Patients were prospectively followed with computed tomography (CT) scans performed preoperatively, immediate postoperatively, and at last follow-up (>2 years). The primary outcomes were 3D-corrected CT scan measurements of glenoid version, PHS, and progression of glenoid erosion. Secondary outcomes included functional outcome scores, return to activities, and revision rate and complications.

RESULTS

At a mean follow-up of 4.5 years (2-9.5 years), the prosthesis survival was 95% (39 of 41). No patient has been reoperated for painful glenoid erosion. The mean glenoid retroversion decreased from 17.1° ± 7.5° preoperatively to 8.3° ± 8.2° at last follow-up (P = .001), and the mean PHS from 74% to 56.5% (P = .001) based on the scapular plane and from 59.9% to 50.3% based on the glenoid plane. The humeral head was recentered in 97% according to the glenoid surface and 71% according to the scapular plane. Correction of PHS in the scapular plane was highly correlated to correction of glenoid retroversion (P < .001). CT scan measurements showed that the average total medialization was 3.7 ± 3.2 mm (2.0 ± 1.8 mm due to reaming and only 1.7 ± 2.4 mm due to erosion). The adjusted Constant Score increased from 43% ± 13% to 97% ± 16% and the Subjective Shoulder Value from 38% ± 14% to 84% ± 12% (P < .001). Overall, 84% of active patients returned to work, and all patients returned to sports.

CONCLUSION

In B2 and B3 glenoid arthritis, corrective, concentric glenoid reaming combined with HA-PYC improves centering of the humeral head and shows a low risk of painful glenoid erosion at midterm follow-up. The combined procedure results in excellent functional outcomes and high prosthesis survivorship at midterm follow-up. HA-PYC and C2 reaming of the glenoid is an alternative shoulder arthroplasty for young/active patients with type B glenoid osteoarthritis who want to return to work or sports practice.

Surface texture analysis of different focal knee resurfacing implants after 6 and 12 months in vivo in a goat model

The clinical success of osteochondral implants depends significantly on their surface properties. In vivo, an implant may roughen over time which can decrease its performance. The present study investigates whether changes in the surface texture of metal and two types of polycarbonate urethane (PCU) focal knee resurfacing implants (FKRIs) occurred after 6 and 12 months of in vivo articulation with native goat cartilage. PCU implants which differed in stem stiffness were compared to investigate whether the stem fixating the implant in the bone influences surface topography. Using optical profilometry, 19 surface texture parameters were evaluated, including spatial distribution and functional parameters obtained from the material ratio curve. For metal implants, wear during in vivo articulation occurred mainly via material removal, as shown by the significant decrease of the core-valley transition from 91.5% in unused implants to 90% and 89.6% after 6 and 12 months, respectively. Conversely, for PCU implants, the wear mechanism consisted in either filling of the valleys or flattening of the surface by dulling of sharp peaks. This was illustrated in the change in roughness skewness from negative to positive values over 12 months of in vivo articulation. Implants with a softer stem experienced the most deformation, shown by the largest change in material ratio curve parameters. We therefore showed, using a detailed surface profilometry analysis, that the surface texture of metal and two different PCU FKRIs changes in a different way after articulation against cartilage, revealing distinct wear mechanisms of different implant materials.

Glenoid wear after humeral head replacement with using a single implant in patients with cuff tear arthropathy more than five years

BACKGROUND

The aim of this study was to investigate glenoid wear in patients with humeral head replacement with a smaller humeral head, who were observed for >5 years, and to examine the relationship between radiographic changes and clinical outcome.

METHODS

In this study, 41 shoulders of 41 patients (13 men, 28 women) were followed up for >5 years. The mean patient age at the time of surgery was 70.5 years. The average follow-up period at short-term was 26.0 months, and intermediate-term was 66.5 months. We classified glenoid wear into four grades (i.e., Grade 0 to Grade 3). Age, sex, clinical scores, and range of motion were investigated in relation to the grade of glenoid wear. Radiographs of glenoid wear evaluated in the short-term were subsequently compared to radiographs obtained in the intermediate-term period.

RESULTS

At the final follow-up, 16 (39%) patients had Grade 0 wear, 11 (27%) patients had Grade 1 wear, 10 (24%) patients had Grade 2 wear, and 4 (10%) patients had Grade 3 wear. The University of California-Los Angeles score, Japanese Orthopaedic Association score, and active forward flexion were significantly lower in the Grade 3 patients; however, Grade 3 patients did not have significant pain. No significant difference in age, sex, Constant score, active external rotation, and active internal rotation in relation to the grade of glenoid wear was observed. In total, 25 (61%) patients showed a progression of glenoid wear. Cases in which glenoid wear progressed after 4 years after surgery were rare. Two patients of Grade 3 underwent total shoulder arthroplasty revision at 16 months and 38 months, respectively.

CONCLUSIONS

Glenoid wear occurred in 61% of patients at 5 years follow-up. Pain of Grade 3 patients was mild, therefore, if pain is not severe, revision surgery may not be necessary.

Hip Spacers with a Metal-on-Cement Articulation Did Not Show Significant Surface Alterations of the Metal Femoral Head in Two-Stage Revision for Periprosthetic Joint Infection

Two-stage revision is considered the gold standard treatment for chronic periprosthetic joint infection (PJI). During the interim period, between explantation of the infected hip endoprosthesis and revision arthroplasty, individually formed articulating hip spacers made of polymethylmethacrylate (PMMA) bone cement can be used to provide better soft tissue preservation, local antibiotic release, and improved postoperative mobilization. If effective prevention from luxation is achieved, hip function and hence overall patient satisfaction is improved. Zirconium oxide particles inside conventional PMMA bone cement, however, are known to enhance third-body wear, which may cause alterations of the metal head in the articulating spacer and hence become a serious risk for the patient. Therefore, the aim of our study was to analyze whether the articular surface of cobalt-chrome (CoCr) femoral heads is significantly altered in the setting of a metal-on-cement articulation during the interim period of two-stage revision for PJI. We analyzed a consecutive series of 23 spacer cases and compared them with femoral heads from two series of conventional hip arthroplasty revisions with metal-on-polyethylene articulations and different time intervals in situ. To investigate metallic wear, the femoral heads were thoroughly examined, and their surface roughness was measured and analyzed. We found no significant differences between the two conventional hip arthroplasty groups, despite their very different times in situ. Furthermore, the individually different times in situ within the spacer group had no significant impact on surface roughness, either. Compared with the spacer group, the surface roughness of the metal femoral heads from both conventional hip arthroplasty groups were even higher. Within the spacer group, roughness parameters did not show significant differences regarding the five predefined locations on the metal head. We conclude that metal-on-cement articulations do not cause enhanced surface alterations of the metal femoral head and hence do not limit the application in articulating hip spacers in the setting of two-stage revision for PJI.

Hemiarthroplasties: the choice of prosthetic material causes different levels of damage in the articular cartilage

BACKGROUND

Hemiarthroplasty has clear advantages over alternative procedures and is used in 20% of all shoulder joint replacements. Because of cartilage wear, the clinical outcome of hemiarthroplasty is unreliable and controversial. This paper suggests that the optimal choice of prosthetic material may reduce cartilage degeneration and improve the reliability of the procedure. The specific objectives were to assess 3 materials and assess how the severity of arthritis might affect the choice of prosthetic material.

METHODS

A CoCr alloy, an AL₂O₃ ceramic, and a polycarbonate urethane polymer (PCU) were mechanically tested against 5 levels of human osteoarthritic cartilage (from intact to severely arthritic, n = 45). A high friction coefficient, a decrease in Young's modulus, an increase in permeability, a decrease in relaxation time, an increase in surface roughness, and a disrupted appearance of the cartilage after testing were used as measures of cartilage damage. The biomaterial that caused minimal cartilage damage was defined as superior.

RESULTS

The CoCr caused the most damage. This was followed by the AL₂O₃ ceramic, whereas the PCU caused the least amount of damage. Although the degree of arthritis had an effect on the results, it did not change the trend that CoCr performed worst and PCU the best.

DISCUSSION AND CONCLUSION

This study indicates that ceramic implants may be a better choice than metals, and the articulating surface should be as smooth as possible. Although our results indicate that the degree of arthritis should not affect the choice of prosthetic material, this suggestion needs to be further investigated.