A two-year comparison of reverse total shoulder arthroplasty mini-humeral tray and augmented mini-glenoid baseplate implants vs. standard implants

BACKGROUND

Patients who undergo reverse total shoulder arthroplasty (RTSA) are getting younger with greater function expectations. This retrospective, longitudinal study of prospectively collected data compared perceived shoulder function and strength, active shoulder mobility, radiographic evidence of scapular notching, and implant survival over the initial 2-years post-RTSA among patient groups who received either standard central fixation point liner and glenoid baseplate implants, or lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants.

MATERIALS AND METHODS

Patients who underwent primary RTSA using standard central fixation point liner and glenoid baseplate implants (Group 1, n = 180) were compared with patients who underwent primary RTSA using lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants (Group 2, n = 53) for active shoulder mobility, American Shoulder and Elbow Surgeons (ASES) score, perceived ability to lift 10 lbs (4.5 kg) overhead, radiographic evidence of scapular notching, and implant survival. Data was collected pre-surgery, 6-weeks, 6-months, 1-year, and 2-years post-RTSA (p ≤ 0.05).

RESULTS

More Group 2 patients had more complex B or C Walch glenoid morphology, while Group 1 had more A1 or A2 types (p ≤ 0.001). Group 2 had greater active shoulder flexion at 6-months, 1-year, and 2-years (p ≤ 0.018) and external rotation (in adduction) at 6-months and 2-years (p ≤ 0.004) compared to Group 1, with higher ASES scores at 6-months and 2-years (p ≤ 0.026) (with small-to-medium effect sizes), and with more patients meeting or exceeding the minimal clinically important difference (MCID) at 2-years (p = 0.045) and patient acceptable symptomatic state (PASS) levels at 6-months, 1-year and 2-years (p ≤ 0.045). Scapular notching was identified in six of 53 (11.3%) Group 2 patients and in 32 of 180 (17.7%) Group 1 patients. Group 1 patients had more grade 2 or greater scapular notching grades compared to Group 2 (p = 0.04). Implant survival was comparable with Group 1 = eight of 180 (4.4%) and Group 2 = 1 of 53 (1.9%) of patients requiring removal for 95.6% and 98.1% implant survival, respectively.

CONCLUSION

Limited scapular notching and excellent implant survival was observed in both groups. Despite including individuals with more complex glenoid deficiency, patients receiving the lower size profile implants generally displayed better active shoulder mobility and perceived shoulder function compared to those who received standard implants. These patients also more frequently met or exceeded the MCID by 2-years post-RTSA and PASS levels by 6-months, 1-year, and 2-years post-RTSA, with lower scapular notching grades.

LEVEL OF EVIDENCE

Retrospective comparative study.

The Effect of Different Antibiotic Combinations in Calcium Sulfate Cement on the Growth of Cutibacterium acnes and Staphylococcus Periprosthetic Shoulder Infection Isolates

BACKGROUND

Prosthetic joint infections (PJI) of the shoulder are a devastating complication of shoulder arthroplasty and are commonly caused by Staphylococcus and Cutibacterium acnes. Absorbable calcium sulfate beads are sometimes used for delivering antibiotics in PJI. This study evaluates the in vitro effect of different combinations of gentamicin, vancomycin, and ertapenem in beads made from calcium sulfate cement on the growth of C. acnes and coagulase-negative Staphylococcus strains.

METHODS

Three strains of C. acnes and five strains of coagulase-negative Staphylococcus from clinically proven shoulder PJI were cultured and plated with calcium sulfate beads containing combinations of vancomycin, gentamicin, and ertapenem. Plates with C. acnes were incubated anaerobically while plates with Staphylococcus were incubated aerobically at 37°C. Zones of inhibition were measured at intervals of 3 and 7 days using a modified Kirby Bauer technique, and beads were moved to plates containing freshly streaked bacteria every 7th day. This process was run in triplicate over the course of 56 days. Statistical analysis was conducted using SPSS v. 28 with repeated measures ANOVA and pairwise comparisons with Tukey correction.

RESULTS

In experiments with C. acnes, beads containing ertapenem + vancomycin and vancomycin alone formed the largest zones of inhibition over time (p<.001). In experiments with Staphylococcus, beads containing vancomycin alone formed the largest zones of inhibition over time for all five strains (p<.001). Zones of inhibition were 1.4x larger for C. acnes than for Staphylococcus with beads containing vancomycin alone. For both C. acnes and Staphylococcus, beads containing ertapenem had the strongest initial effect, preventing all bacterial growth in C. acnes and almost all growth for Staphylococcus during the first week but dropping substantially by the second week. Beads containing gentamicin alone consistently created smaller zones of inhibition than beads containing vancomycin alone, with vancomycin producing zones 5.3x larger than gentamicin in C. acnes and 1.3x larger in Staphylococcus (p<.001).

DISCUSSION

These data suggest that for both C. acnes and Staphylococcal species, calcium sulfate beads impregnated with vancomycin were most effective at producing a robust antibiotic effect. Additionally, ertapenem may be a viable supplement in order to create a more potent initial antibiotic effect but is not as effective as vancomycin when used alone. Gentamicin alone was not effective in maintaining consistent and long-term antibiotic effects. These results indicate that amongst the antibiotics currently commercially available to be used with calcium sulfate, vancomycin is consistently superior to gentamicin in the setting of C. acnes and coagulase negative Staphylococci.

Mini-augmented glenoid baseplate and mini-humeral tray reverse total shoulder arthroplasty implant comparisons: two-year clinical outcomes

BACKGROUND

Augmented glenoid baseplate and offset humeral tray reverse total shoulder arthroplasty (RTSA) implants may decrease the mechanical impingement that creates scapular notching and improve shoulder function. This study evaluated the clinical efficacy of three different RTSA glenoid baseplate and offset humeral tray combinations for patient-reported shoulder function, pain and instability, radiographic imaging evidence of glenoid baseplate or humeral stem subsidence and migration, bony changes associated with implant loosening, and scapular notching over the initial 2 years post-RTSA. Primary outcomes included active shoulder mobility, perceived function, pain, instability, scapular notching, and implant survival.

METHODS

Sixty-seven patients from 6 research sites received one of three different glenoid baseplate and humeral tray combinations. Group 1 (n = 21) received a mini-augmented glenoid baseplate with a standard humeral tray; Group 2 (n = 23) received a standard glenoid baseplate and a mini-humeral tray with 3 trunnion offset options; Group 3 (n = 23) received both a mini-augmented glenoid baseplate and a mini-humeral tray with 3 trunnion offset options. Subjects underwent radiologic evaluation, completed the ASES scale, the EQ-5D-5L quality of life scale, VAS shoulder pain and instability questions, and active shoulder mobility measurements pre-operatively, and 6-weeks, 6-months, 1-2 years post-RTSA.

RESULTS

Improved active shoulder mobility, quality of life, perceived function, decreased shoulder pain and instability, excellent implant survival and minimal scapular notching were observed for all groups. Group 3 had better overall active shoulder mobility than the other groups and better perceived function than Group 1.

CONCLUSION

The group that received the mini-augmented glenoid baseplate and mini-humeral tray combination had better overall active shoulder flexion, external rotation at 90° abduction, and internal rotation. This group also had better perceived shoulder function compared to the group that received a mini-augmented glenoid baseplate with a standard humeral tray.

In vitro and in vivo assessment of extended duration cathodic voltage-controlled electrical stimulation for treatment of orthopedic implant-associated infections

Effective treatment of orthopedic implant-associated infections (IAIs) remains a clinical challenge. The in vitro and in vivo studies presented herein evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) to titanium implants inoculated with preformed bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that combining vancomycin therapy (500 µg/mL) with application of CVCES at -1.75 V (all voltages are with respect to Ag/AgCl unless otherwise stated) for 24 h resulted in 99.98% reduction in the coupon-associated MRSA colony-forming units (CFUs) (3.38 × 103 vs. 2.14 × 107 CFU/mL, p < 0.001) and a 99.97% reduction in the planktonic CFU (4.04 × 104 vs. 1.26 × 108 CFU/mL, p < 0.001) as compared with the no treatment control samples. The in vivo studies utilized a rodent model of MRSA IAIs and showed a combination of vancomycin therapy (150 mg/kg twice daily) with CVCES of -1.75 V for 24 h had significant reductions in the implant associated CFU (1.42 × 101 vs. 1.2 × 106 CFU/mL, p < 0.003) and bone CFU (5.29 × 101 vs. 4.48 × 106 CFU/mL, p < 0.003) as compared with the untreated control animals. Importantly, the combined 24 h CVCES and antibiotic treatments resulted in no implant-associated MRSA CFU enumerated in 83% of the animals (five out of six animals) and no bone-associated MRSA CFU enumerated in 50% of the animals (three out of six animals). Overall, the outcomes of this study have shown that extended duration CVCES therapy is an effective adjunctive therapy to eradicate IAIs.

386. Blue Light Reduces Cutibacterium (Propionibacterium) Acnes Bacterial Burden: Orthopedic Shoulder Infection Prevention Strategy?

Background

Cutibacterium acnes (C. acnes) is a common shoulder periprosthetic joint infection (PJI). Blue light (BL) is effectively used in the dermatologic clinical setting against acne vulgaris caused by C. acnes. Photodynamic therapy (PDT) is the use of light source and photosensitizer (PS) to enhance antimicrobial activity. We studied the effect of PDT using BL and PS in vitro on shoulder PJI isolates of C. acnes.

Methods

19 strains were grown in thioglycollate medium and diluted in sterile normal saline (NS) to a turbidity of 0.5 McFarland standard; OD₆₀₀ of 0.1 to 0.15. 250 µL with PS added were placed in 96-well plates at 37ºC, exposed to BL (415 nm) placed 1 cm above for 0 to 60 minutes at 15-minute intervals. Susceptibility to BL alone, and BL with PSs such as riboflavin (R, Vit B2), fluorescein (F) or demeclocycline (tetracycline antibiotic, “D”) were studied. After serial 10-fold dilution with NS, 3 µL of each well were spotted onto Brucella Blood Agar plates and incubated anaerobically for 48 hours. Eradication was defined as below the limit of detection. Definitions include Sensitive (S) if 3-log decrease in bacterial density or eradication at any time point, Weakly Sensitive (WS) with 1- to 3-log decrease and Resistant (R) with no decrease.

Results

Based on BL alone, (n = 19). 68% strains were S, 32% were resistant. BL+ R (10 μg/mL) effect in 25% (n = 3) and exerted a protective effect against 33% (n = 4). BL+ F (1 μg/mL) potentiated in 67%. BL+ D (0.1–1.5 μg/mL) in 83% of strains tested. The most resistant strain was eradicated using BL + D at an increased concentration of demeclocycline (2.5 μg/mL).

Conclusion

F and D enhanced the potential for eradication compared with BL exposure alone. R was a photo-protectant to BL for select strains. Prior studies have hypothesized endogenous intracellular porphyrins excited by BL causing energy transfer and production of highly cytotoxic reactive oxygen species causing bacterial death. Future clinical research evaluating the use of preoperative PS and surgical site exposure to BL as a preventative PJI strategy are needed. Our research shows that BL with the addition of PS significantly reduces the bacterial burden of clinically relevant PJI shoulder isolates of C. acnes in an in vitro model.

Disclosures

All authors: No reported disclosures.

Outcomes of Uncemented Versus Cemented Reverse Shoulder Arthroplasty for Proximal Humerus Fractures

Reverse shoulder arthroplasty (RSA) for proximal humerus fractures (PHFs) is traditionally performed with cemented humeral fixation. The purpose of this study was to compare the clinical and radiographic outcomes of cemented and cementless RSA for PHF. Between 2010 and 2014, 38 acute PHFs were treated with RSA and followed for a minimum of 2 years (mean, 37 months; range, 24-66 months). The mean time from fracture to RSA was 7 days (range, 1-30 days). Humeral stems were cemented in 19 shoulders and uncemented in 19 shoulders. Outcome measures included visual analog scale pain scores, range of motion, postoperative Quick Disabilities of the Arm, Shoulder and Hand scores, American Shoulder and Elbow Surgeons scores, and radiographic parameters. The 2 groups had similar visual analog scale pain scores, postoperative range of motion, and Quick Disabilities of the Arm, Shoulder and Hand scores (P>.05). American Shoulder and Elbow Surgeons scores and satisfaction scores were significantly higher with cemented humeral fixation (76.3 vs 48.0, P=.005; 1.2 vs 1.8, P=.04). Radiographically, there was no difference in terms of tuberosity healing, component loosening, or notching (P>.05). Reverse shoulder arthroplasty provides pain relief for PHF, regardless of humeral fixation. In this cohort, cementless fixation was associated with worse patient-reported outcomes, although no correlation could be established with pain, motion, or tuberosity healing. Further studies are required before cementless fixation can be recommended for RSA for fracture. [Orthopedics. 2019; 42(2):e236-e241.].

Location and number of cortical fixation points and the effect on reference base stability during computer-navigated total knee arthroplasty

This study investigated 2 methods of reference base fixation for computer navigation markers for computer-navigated total knee arthroplasty. Five cadaveric specimens were used to test a 1-pin and 3-pin base system. A navigation system (Stryker Navigation, Kalamazoo, Mich) was used for testing with applied loads and torques to the reference base. Changes in distance from a verification point as well change in alignment were recorded. The change in distance to a reference point as well as the change in alignment data was significantly different at 65 N of applied load with the 3-pin construct being more stable (P = .02). The results suggest that 3-pin fixation in the metaphyseal portion of the distal femur is more stable than a single-pin bicortical construct.

Effect of one- and two-pin reference anchoring systems on marker stability during total knee arthroplasty computer navigation

OBJECTIVE

This study investigated different infrared marker reference base attachments in cadaveric bone and their effects on alignment outcome when different loads were applied.

MATERIAL AND METHODS

Five cadaveric specimens were used to test four reference base attachments: a locking one-pin (4.0 mm and 5.0 mm pins) and a two-pin clamp (Hoffman fixator, 3.0 mm and 5.0 mm pins, Stryker Inc., NJ). Each was tested with metaphyseal and diaphyseal attachments. A navigation system (Stryker Navigation, MI) was used for testing with applied incremental loads and torques (65 N and 1.0 Nm) to the different reference base configurations.

RESULTS

With 65 N the maximum change in distance to a verification point was 4.3 + 1.6 mm with the 4.0 mm locking pin in metaphyseal bone. No difference in verification point distances was found with any two-pin configuration. Alignment changes greater than 4 degrees resulted with the 65 N loads and a 4.0 mm pin.

CONCLUSION

The results may prove beneficial in comparing the resulting error of different manufacturers and allow surgeons to realize the variability that may occur through incidental contact in the operating room.