Biomechanical consequences of humeral component malpositioning after anatomical total shoulder arthroplasty

PurposeLiterature describes the concern of an overstuffed shoulder joint after a resurfacing humeral head implant (RHHI). The purpose of this study was to evaluate inter-observer variability of (1) the critical shoulder angle (CSA), (2) the length of the gleno-humeral offset (LGHO), and (3) the anatomic center of rotation (COR) in a patient population operated with a Global Conservative Anatomic Prosthesis (CAP) RHHI. The measurements were compared between the revision and non-revision groups to find predictive indicators for failure.MethodsPre- and postoperative radiographs were retrieved from 48 patients who underwent RHHI from 2007 to 2009 using a Global CAP hemiarthroplasty for end-stage osteoarthritis. This cohort consisted of 36 females (12 men) with a mean age of 77 years (SD 7.5). Two musculoskeletal radiologist and two specialized shoulder orthopedic surgeons measured the CSA, LGHO, and COR of all patients.ResultsThe inter-observer reliability showed excellent reliability for the CSA, LGHO, and the COR, varying between 0.91 and 0.98. The mean COR of the non-revision group was 4.9 mm (SD 2.5) compared to mean COR of the revision group, 8 mm (SD 2.2) (p < 0.01). The COR is the predictor of failure (OR 1.90 (95%Cl 1.19–3.02)) with a cut of point of 5.8 mm. The mean CSA was 29.8° (SD 3.9) There was no significant difference between the revision and non-revision groups (p = 0.34). The mean LGHO was 2.6 mm (SD 3.3) post-surgery. The mean LGHO of the revision group was 3.9 (SD 1.7) (p = 0.04) post-surgery. Despite the difference in mean LGHO, this is not a predictor for failure.ConclusionThe CSA, LGHO, and COR can be used on radiographs and have a high inter-observer agreement. In contrast with the CSA and LGHO, we found a correlation between clinical failure and revision surgery in case of a deviation of the COR greater than 5 mm.Trial registrationInstitutional review board, number: ACLU 2016.0054, Ethical Committee number: CBP M1330348. Registered 7 November 2006.

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“…Multiple studies use different cut-off points to define overstuffing of the gleno-humeral joint [8, 27–30, 32].…”

Section: Discussionmentioning

confidence: 99%

Overstuffing in resurfacing hemiarthroplasty is a potential risk for failure

et al. 2019

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“…In addition, though minor, there is a slight error in measurements using handheld point calipers. Numerous authors have demonstrated that accurate implant placement is crucial for restoring normal glenoid kinematics and motion [5][6][7][8] and others have shown worsening clinical outcomes and higher rates of pain and implant loosening when implants were not placed anatomically. [1][2][3] This is such an important concept that it essentially was the primary inspiration for creating the implant under investigation in this study.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of Humeral Articular Surface Restoration in a Novel Anatomic Shoulder Arthroplasty Technique and Design: A Cadaveric Study

Goldberg

Akyuz²,

Murthi

et al. 2018

Journal of Shoulder and Elbow Arthroplasty

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Introduction: Accurate restoration of the humeral joint line during shoulder arthroplasty is critical to maximizing outcomes. However, clinical studies show that both resurfacing and stemmed arthroplasty systems routinely do not restore the articular surface accurately, even by experienced surgeons. The purpose of this study was to evaluate surgeons' ability to recreate the 3-dimensional geometry of the proximal humerus using a newly developed arthroplasty system. Methods: The difference in articular surface location before and after arthroplasty was measured using a new nonspherical arthroplasty system which uses a calibrated multiplanar osteotomy technique matching bone removal thickness to implant thickness. Eight human cadaver specimens were measured at 9 separate point locations over the articular surface from a fixed reference point on the lateral humerus. We repeated the measurements after bone preparation with the implant trial. Articular surface points >3.0 mm from their original location were considered outliers, based on literature. Results: Average absolute deviation of each point on the articular surface measured 0.9 AE 0.7 mm (range: 0.0-2.7 mm) from preoperative to postoperative articular surface location. All (72/72) points measured were below the 3.0 mm outlier threshold from their original location. Conclusion: Surgeons using the new system, ie, using a nonspherical head design and a calibrated multiplanar osteotomy surgical technique, were able to restore the joint line accurately with minimal (<1.0 mm) change from preop, with no outliers. Arthroplasty systems matching bone removal directly to implant thickness potentially may improve the reproducibility of arthroplasy and improve shoulder kinematics compared to traditional systems.

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“…performed a biomechanical analysis using a 3-dimensional numerical musculoskeletal model of the glenohumeral joint to show that even a small error in positioning of the humeral component can impact functional outcome and life-time of an anatomic TSA. 19 Inferior malpositioning of the head resulted in impingement and limited abduction, while superior malpositioning resulted in increased risk of subluxation. Both inferior and superior malpositioning caused increased stress on the cement mantle of the glenoid.…”

Section: Discussionmentioning

confidence: 99%

Anatomic humeral head replacement with a press-fit prosthesis: An in vivo radiographic study

et al. 2017

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Successful total shoulder arthroplasty is, in part, dependent on anatomic reconstruction of the glenohumeral joint. The purpose of this study was to evaluate the post-operative anatomy of total shoulder arthroplasty with an anatomic implant design in patients with primary glenohumeral osteoarthritis and compare it to published normative anatomic measurements. Fifty-one patients (56 shoulders) with primary glenohumeral osteoarthritis were treated with a press-fit humeral component as part of a total shoulder arthroplasty (Aequalis, Tornier, Edina, Minnesota). Analysis of postoperative true anterior posterior radiographs was performed with use of a custom software algorithm. The mean humeral inclination (head-shaft angle), mean humeral implant anatomical humeral axis, mean greater tuberosity height, and mean humeral head center offset (medial offset) were 135.4±5.1°, 1.73±1.7°, 6.9±2.4 mm, and 3.8±1.8 mm, respectively. All parameters were within the ranges reported in the literature for normal shoulders except the mean humeral head center offset, which was less than reported in the literature. Anatomic parameters of a total shoulder arthroplasty can be achieved with an anatomically designed, modular adaptable press-fit design. Reduced medial humeral head center offset was likely dependent upon implant specific design parameters.

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Biomechanical consequences of humeral component malpositioning after anatomical total shoulder arthroplasty

Cited by 52 publications

References 24 publications

Overstuffing in resurfacing hemiarthroplasty is a potential risk for failure

Overstuffing in resurfacing hemiarthroplasty is a potential risk for failure

Accuracy of Humeral Articular Surface Restoration in a Novel Anatomic Shoulder Arthroplasty Technique and Design: A Cadaveric Study

Anatomic humeral head replacement with a press-fit prosthesis: An in vivo radiographic study

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