Outcomes of Femoral Head Allograft for the Management of Glenoid Bone Defects in Revision Reverse Shoulder Arthroplasty: A Case-Controlled Study

BACKGROUND

Revision shoulder arthroplasty often requires management of glenoid bone defects. Options include using allograft, harvesting iliac crest autograft, or using augmented metal components. The purpose of this study is to report outcomes of revision shoulder arthroplasty requiring management of glenoid bone defects with femoral head allograft in a large cohort of patients using a single reverse shoulder implant system and compare them to a matched cohort based on the indication for surgery. Outcomes of patients who had successful glenoid reconstruction were compared to those that required a re-revision, and to a control group that was revised without the need for bone graft.

METHODS

This was a retrospective review of data collected from 2009 to 2018. There were 36 patients in the bone graft group and 52 in the control group. All patients underwent revision to a reverse shoulder arthroplasty to manage a failed total shoulder arthroplasty (n = 29 and 11), hemiarthroplasty (n = 1 and 24), or reverse shoulder arthroplasty (n = 6 and 17). All patients had a minimum of 2 years of clinical follow-up. The primary endpoint was survival of baseplate fixation. Secondary outcomes included range of motion and functional outcome scores. Patients that had recurrent baseplate failure and were re-revised were compared to patients with bone graft that did not require additional surgery, and to patients who were revised without the need for bone graft. Patients who required revisions for reasons other than recurrent baseplate failure were also recorded.

RESULTS

Five of 36 (14%) patients had recurrent baseplate failure. Mean time to failure was 12 months. Three of 5 had successful re-implantation of another baseplate. Two of 5 were revised to a hemi arthroplasty after failure of their revisions. Preoperative ASES scores were 31 in the grafted patients that did not require re-revision, 39 in the grafted patients that required re-revision, and 33 in the control group. Final ASES scores were 64, 36, and 56, respectively. One patient required revision surgery not related to baseplate failure. There were no baseplate failures in the control group.

CONCLUSION

The use of femoral head allograft to manage glenoid bone defects in the revision setting produces predictable improvement in functional outcomes that is not inferior to those in patients revised without bone graft. However, there is a 14% rate of baseplate failure.

Biomaterials with structural hierarchy and controlled 3D nanotopography guide endogenous bone regeneration

Biomaterials without exogenous cells or therapeutic agents often fail to achieve rapid endogenous bone regeneration with high quality. Here, we reported a class of three-dimensional (3D) nanofiber scaffolds with hierarchical structure and controlled alignment for effective endogenous cranial bone regeneration. 3D scaffolds consisting of radially aligned nanofibers guided and promoted the migration of bone marrow stem cells from the surrounding region to the center in vitro. These scaffolds showed the highest new bone volume, surface coverage, and mineral density among the tested groups in vivo. The regenerated bone exhibited a radially aligned fashion, closely recapitulating the scaffold's architecture. The organic phase in regenerated bone showed an aligned, layered, and densely packed structure, while the inorganic mineral phase showed a uniform distribution with smaller pore size and an even distribution of stress upon the simulated compression. We expect that this study will inspire the design of next-generation biomaterials for effective endogenous bone regeneration with desired quality.

3D Hybrid Nanofiber Aerogels Combining with Nanoparticles Made of a Biocleavable and Targeting Polycation and MiR-26a for Bone Repair

The healing of large bone defects represents a clinical challenge, often requiring some form of grafting. Three-dimensional (3D) nanofiber aerogels could be a promising bone graft due to their biomimetic morphology and controlled porous structures and composition. miR-26a has been reported to induce the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and facilitate bone formation. Introducing miR-26a with a suitable polymeric vector targeting BMSCs could improve and enhance the functions of 3D nanofiber aerogels for bone regeneration. Herein, we first developed the comb-shaped polycation (HA-SS-PGEA) carrying a targeting component, biocleavable groups and short ethanolamine (EA)-decorated poly(glycidyl methacrylate) (PGMA) (abbreviated as PGEA) arms as miR-26a delivery vector. We then assessed the cytotoxicity and transfection efficiency of this polycation and cellular response to miR-26a-incorporated nanoparticles (NPs) in vitro. HA-SS-PGEA exhibited a stronger ability to transport miR-26a and exert its functions than the gold standard polyethyleneimine (PEI) and low-molecular-weight linear PGEA. We finally examined the efficacy of HA-SS-PGEA/miR-26a NPs loaded 3D hybrid nanofiber aerogels showing a positive effect on the cranial bone defect healing. Together, the combination of 3D nanofiber aerogels and functional NPs consisting of a biodegradable and targeting polycation and therapeutic miRNA could be a promising approach for bone regeneration.

Tethering peptides onto biomimetic and injectable nanofiber microspheres to direct cellular response

Biomimetic and injectable nanofiber microspheres (NMs) could be ideal candidate for minimally invasive tissue repair. Herein, we report a facile approach to fabricate peptide-tethered NMs by combining electrospinning, electrospraying, and surface conjugation techniques. The composition and size of NMs can be tuned by varying the processing parameters during the fabrication. Further, bone morphogenic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) mimicking peptides have been successfully tethered onto poly(ε-caprolactone) (PCL):gelatin:(gelatin-methacryloyl) (GelMA)(1:0.5:0.5) NMs through photocrosslinking of the methacrylic group in GelMA and octenyl alanine (OCTAL) in the modified peptides. The BMP-2-OCTAL peptide-tethered NMs significantly promote osteogenic differentiation of bone marrow-derived stem cells (BMSCs). Moreover, human umbilical vein endothelial cells (HUVECs) seeded on VEGF mimicking peptide QK-OCTAL-tethered NMs significantly up-regulated vascular-specific proteins, leading to microvascularization. The strategy developed in this work holds great potential in developing a biomimetic and injectable carrier to efficiently direct cellular response (Osteogenesis and Angiogenesis) for tissue repair.

Body mass index as a risk factor for dislocation of total shoulder arthroplasty in the first 30 days

Background

Dislocation of total shoulder arthroplasty has an incidence as high as 31%. Obesity is one of many proposed risk factors, but no consensus exists on this relationship. The purpose of this study was to determine whether there is a relationship between body mass index (BMI) and dislocation of total shoulder arthroplasty.

Methods

The National Surgical Quality Improvement Program database was used to identify patients older than 50 years who underwent anatomic or reverse total shoulder arthroplasty between the years 2012 and 2016 for primary or secondary osteoarthritis, post-traumatic arthritis, or cuff tear arthropathy. Patients requiring reoperation or readmission for dislocation were identified by Current Procedural Terminology code. The relationship between World Health Organization BMI classification and dislocation was assessed.

Results

A total of 9382 patients were identified; 46% were male and 54% female, with an average age of 68.7 years (range 50-90) and average BMI of 31.2 (range 15.1-79.3). There were only 24 dislocation events within the first 30 days after the procedure (0.26%). Ten of 24 (42%) occurred after discharge. Seventy percent of cases (17 of 24) required an open procedure. Underweight patients (BMI < 18.5) experienced the highest dislocation rate (1/50, 2.00%), whereas overweight patients (BMI 25-29.9) experienced the lowest dislocation rate (3/3069, 0.1%).

Conclusion

The rate of dislocation of total shoulder arthroplasty in the acute postoperative period differs across categories of BMI. However, there does not appear to be a linear association between BMI and risk of dislocation of total shoulder arthroplasty. Further studies are required to elucidate the risk factors for total shoulder dislocation.

Novel 3D Hybrid Nanofiber Aerogels Coupled with BMP-2 Peptides for Cranial Bone Regeneration

An ideal synthetic bone graft is a combination of the porous and nanofibrous structure presented by natural bone tissue as well as osteoinductive biochemical factors such as bone morphogenetic protein 2 (BMP-2). In this work, ultralight 3D hybrid nanofiber aerogels composed of electrospun PLGA-collagen-gelatin and Sr-Cu codoped bioactive glass fibers with incorporation of heptaglutamate E7 domain specific BMP-2 peptides have been developed and evaluated for their potential in cranial bone defect healing. The nanofiber aerogels are surgically implanted into 8 mm × 1 mm (diameter × thickness) critical-sized defects created in rat calvariae. A sustained release of E7-BMP-2 peptide from the degradable hybrid aerogels significantly enhances bone healing and defect closure over 8 weeks in comparison to unfilled defects. Histomorphometry and X-ray microcomputed tomography (µ-CT) analysis reveal greater bone volume and bone formation area in case of the E7-BMP-2 peptide loaded hybrid nanofiber aerogels. Further, histopathology data divulged a near complete nanofiber aerogel degradation along with enhanced vascularization of the regenerated tissue. Together, this study for the first time demonstrates the fabrication of 3D hybrid nanofiber aerogels from 2D electrospun fibers and their loading with therapeutic osteoinductive BMP-2 mimicking peptide for cranial bone tissue regeneration.

Binary Doping of Strontium and Copper Enhancing Osteogenesis and Angiogenesis of Bioactive Glass Nanofibers while Suppressing Osteoclast Activity

Electrospun bioactive glass fibers show great potential as scaffolds for bone tissue engineering due to their architectural biomimicry of the bone extracellular matrix and their composition capable of providing soluble bioactive cues for bone regeneration and remodeling. Trace elements can be doped to further promote osteogenesis and angiogenesis during bone regeneration. Cationic substitution of strontium for calcium in bioactive glass positively enhances osteoblast phenotype, while suppressing osteoclast activity. Further, the addition of copper spontaneously improves the vascularization during neobone formation. The objective of this study was to fabricate and characterize electrospun bioactive glass fibers doped with strontium and copper and evaluate their potential for bone repair/regeneration in vitro. Different ratios of strontium and copper were doped in electrospun bioactive glass fibers. The released strontium and copper from doped fibers could reach effective concentrations within 40 h and last for 4 weeks. These bioactive glass fibers demonstrate their bioactivity by promoting osteoblastic and endothelial cell activity and inhibiting the formation of osteoclasts or bone resorbing cells. Additionally, in vitro cell culture of different cell types in the presence of extraction solutions of the electrospun bioactive glass fibers showed that the dopants achieved their individual goals without causing significant cytotoxicity. Altogether, this novel class of bioactive glass fibers holds great promise for bone regeneration.

Twisting electrospun nanofiber fine strips into functional sutures for sustained co-delivery of gentamicin and silver

Surgical site infections (SSIs) represent the most common nosocomial infection among surgical patients. In order to prevent SSIs in a sustained manner and lessen side effects, we developed a twisting method for generation of nanofiber-based sutures capable of simultaneous delivery of silver and gentamicin. The prepared sutures are composed of core-sheath nanofibers with gentamicin/pluronic F127 in the core and silver/PCL in the sheath produced by co-axial electrospinning. The diameters of obtained sutures range from ~80 μm to ~1.2 mm. The in vitro release profiles of silver and gentamicin exhibit an initial burst followed by a sustained release over 5 weeks. The co-encapsulated sutures were able to kill bacteria much more effectively than gentamicin or silver alone loaded nanofiber sutures, without showing obvious impact on proliferation and migration of dermal fibroblasts and keratinocytes. The gentamicin and silver co-loaded PCL nanofiber sutures may hold great potential for prevention of SSIs.

Expanded 3D Nanofiber Scaffolds: Cell Penetration, Neovascularization, and Host Response

Herein, a robust method to fabricate expanded nanofiber scaffolds with controlled size and thickness using a customized mold during the modified gas-foaming process is reported. The expansion of nanofiber membranes is also simulated using a computational fluid model. Expanded nanofiber scaffolds implanted subcutaneously in rats show cellular infiltration, whereas non-expanded scaffolds only have surface cellular attachment. Compared to unexpanded nanofiber scaffolds, more CD68+ and CD163+ cells are observed within expanded scaffolds at all tested time points post-implantation. More CCR7+ cells appear within expanded scaffolds at week 8 post-implantation. In addition, new blood vessels are present within the expanded scaffolds at week 2. The formed multinucleated giant cells within expanded scaffolds are heterogeneous expressing CD68, CCR7, or CD163 markers. Together, the present study demonstrates that the expanded nanofiber scaffolds promote cellular infiltration/tissue integration, a regenerative response, and neovascularization after subcutaneous implantation in rats. The use of expanded electrospun nanofiber scaffolds offers a promising method for in situ tissue repair/regeneration and generation of 3D tissue models/constructs.

Highly controlled coating of strontium-doped hydroxyapatite on electrospun poly(ɛ-caprolactone) fibers

Electrospun fibers show great potential as scaffolds for bone tissue engineering due to their architectural biomimicry to the extracellular matrix (ECM). Cation substitution of strontium for calcium in hydroxyapatite (HAp) positively influences the mechanism of bone remodeling including enhancing bone regeneration and reducing bone resorption. The objective of this study was to attach strontium-doped HAp (SrHAp) to electrospun poly(ɛ-caprolactone) (PCL) fibers for creation of novel composite scaffolds that can not only mimic the architecture and composition of ECM but also affect bone remodeling favorably. We demonstrated for the first time the highly controlled SrHAp coatings on electrospun PCL fibers. We showed the reproducible manufacturing of composite fiber scaffolds with controllable thickness, composition, and morphology of SrHAp coatings. We further showed that the released strontium and calcium cations from coatings could reach effective concentrations within 1 day and endure more than 28 days. Additionally, the Young's modulus of the SrHAp-coated PCL fibers was up to around six times higher than that of raw fibers dependent on the coating thickness and composition. Together, this novel class of composite fiber scaffolds may hold great promise for bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 753-763, 2017.

Results of closed management of acute dislocation after reverse shoulder arthroplasty

BACKGROUND

Postoperative instability continues to be one of the most common complications limiting outcomes of reverse shoulder arthroplasty (RSA). The optimal management of this complication remains unknown. The purpose of this study was to evaluate the outcomes of patients with postoperative dislocation after RSA managed with closed reduction.

METHODS

All patients who were treated with a closed reduction for dislocation after RSA in the period between May 2002 and September 2011 were identified and retrospectively reviewed. Final outcomes including recurrent instability, need for revision surgery, American Shoulder and Elbow Surgeons outcome score, and range of motion were evaluated.

RESULTS

A total of 21 patients were identified. Nearly 50% of cases (10 of 21) had previous surgery, with 80% (8 of 10) of these being previous arthroplasty. The average time to first dislocation was 200 days, with 62% (13 of 21) occurring in the first 90 days. At average follow-up of 28 months, 62% of these shoulders remained stable (13 of 21), 29% required revision surgery (6 of 21), and 9% remained unstable (2 of 21). The average American Shoulder and Elbow Surgeons score was 68.0 for patients treated with closed reduction for instability and 62.7 for those treated with revision surgery (P = .64).

DISCUSSION

This study shows that an initial dislocation episode after RSA with use of this implant can be successfully managed with closed reduction and temporary immobilization in more than half of cases. Given that outcomes after revision surgery are not different from those after closed treatment, we would continue to recommend an initial attempt at closed reduction in the office setting in all cases of postoperative RSA dislocation.

What is the effect of postoperative scapular fracture on outcomes of reverse shoulder arthroplasty?

BACKGROUND

Postoperative scapular fracture is a common complication after reverse shoulder arthroplasty (RSA). The purpose of this study was to determine its effect on RSA patient outcomes.

METHODS

A retrospective, case-control study of 25 nonoperatively treated postoperative scapular fractures after RSA were analyzed with a minimum 2-year follow-up from surgery and 1-year follow-up from fracture. Eligible patients were matched 1:4 to a control group for age, sex, follow-up time, surgery indication, and primary operation vs revision. Outcome measures, including American Shoulder and Elbow Surgeons (ASES) score and range of motion, were compared between fracture cases and controls. Also analyzed were radiographic features, including fracture location (acromion vs scapular spine) and healing.

RESULTS

Incidence of scapular fracture after RSA in this series was 3.1%. Fractures occurred from 1 to 94 months postoperatively. The revision rate was higher in the fracture group (8% vs. 2%) but did not reach statistical significance (P = .18). Fracture patients had improved (ΔASES, 21) but inferior clinical outcomes, with a postoperative ASES score of 58.0 compared with 74.2 (P ≤ .001). Change in range of motion also diminished in the fracture group, with a mean gain of 26° forward elevation compared with 76° (P < .001). Fracture location (P = .54) or healing (P = .40) did not affect outcome.

CONCLUSION

Postoperative scapular fractures may occur at any point postoperatively; increasing incidence is likely as longer follow-up becomes available. This complication leads to inferior clinical results compared with controls. However, patients show improvement compared with their preoperative measurements, even at longer-term follow-up. Patients with postoperative scapular fractures may have increased risk of revision.

LEVEL OF EVIDENCE

Level III, case-control study, treatment study.

Kinematic impact of size on the existing glenohumeral joint in patients undergoing reverse shoulder arthroplasty

BACKGROUND

Glenohumeral relationships in reverse shoulder arthroplasty patients have not been previously reported. The purpose of this study was to quantify and compare the shoulder spatial relationships and moment arms. Measurements were used to define general size categories and determine if sizes scale linearly for all metrics.

METHODS

Ninety-two shoulders of patients undergoing primary reverse shoulder arthroplasty for functionally-deficient massive rotator cuff tear without bony deformity or deficiency were evaluated using three-dimensional CT reconstructions and computer-aided design software. Multiple glenohumeral relationships (including moment arm) were measured and evaluated for size stratification and linearity. Generalized linear modeling was used to investigate how predictive glenoid height, coronal humeral head diameter, and gender were of greater tuberosity positions.

FINDINGS

The 92 shoulders were grouped based on glenoid height: small (<33.4mm), medium (33.4-38.0mm), and large (>38.0mm). All relationships varied between groups. The humeral head size, glenoid width, lateral offset, and moment arm all independently increased linearly (r(2)≥0.92) but the rate of increase varied (slope range: 0.59-1.92). Glenoid height, coronal humeral head diameter and gender predicted the greater tuberosity position within mean 1.09mm (standard deviation (SD) 0.84mm) of actual position in 90% of the population.

INTERPRETATION

Distinct groups exist based on the size of the glenoid in shoulder arthroplasty patients. Shoulder modeling should account for size groups, sex, and non-uniform linear scaling of morphometric parameters. Prediction of the greater tuberosity offset can be made using sex and size parameters. Clinical implications include appropriate prosthetic size selection and avoiding large deviations in non-anatomic reconstructions.

Femoral remodeling around Charnley total hip arthroplasty is unpredictable

BACKGROUND

There are two unusual remodeling patterns of the proximal femur around well-fixed Charnley total hip arthroplasties: cortical thinning leading to endosteal widening around the femoral component and hypertrophy of the distal femoral cortex. Previous studies have shown remodeling patterns are affected by stem design and occur early postoperatively. It is unclear if these changes are related to patient demographics or if they progress throughout the lifetime of the implant.

QUESTIONS/PURPOSES

We determined if patient demographic variables influence remodeling patterns after cemented Charnley total hip arthroplasty and if the observed remodeling changes persist long-term.

METHODS

We retrospectively reviewed the radiographs of 106 well-fixed Charnley femoral components. Using a novel digital edge detection program, we determined the femoral remodeling pattern and time-related changes in femoral dimensions. The minimum followup was 20 years (mean, 25.3 years; range, 19.5-37 years).

RESULTS

We found no association between remodeling type and age at surgery, sex, preoperative diagnosis, body mass index, or postoperative activity level. There was also no association between initial implant alignment and remodeling type. Cortical thickening in the distal hypertrophy group was an early phenomenon occurring primarily within the first 2 years, whereas cortical thinning begins later and is a more progressive process.

CONCLUSIONS

These data show remodeling after cemented Charnley total hip arthroplasty is not related to patient demographic variables; however, distal cortical hypertrophy can be predicted in the early postoperative period.

Cementless acetabular fixation in patients 50 years and younger at 10 to 18 years of follow-up

The purpose of the study was to evaluate the 10- to 18-year follow-up of cementless acetabular fixation in patients 50 years and younger. We retrospectively reviewed a consecutive group of 118 patients (144 hips) in whom primary total hip arthroplasty had been performed by 2 surgeons using a cementless acetabular component. Two (1.4%) cementless acetabular components were revised because of aseptic loosening. Twenty-four hips (16.7%) were revised for any mechanical failure of the acetabular component mostly related to acetabular liner wear and osteolysis. The average linear wear rate was 0.19 mm per year, which was higher than our previous reports with cemented acetabular fixation. The fiber mesh ingrowth surface of the cementless acetabular component in this study was superior to cemented acetabular components in terms of fixation. However, the high rates of wear and osteolysis have led to poor overall acetabular component construct survivorship.