Total elbow arthroplasty: Influence of implant positioning on functional outcomes

Valgus instability and related factors beyond 2 years following unlinked total elbow arthroplasty

HYPOTHESIS AND BACKGROUND

Total elbow arthroplasty (TEA), categorized into linked and unlinked types, is a commonly reported treatment for rheumatoid arthritis of the elbow. Although unlinked TEA preserves bone, it may result in instability. This study aimed to assess the outcomes of unlinked TEA in rheumatoid arthritis of the elbow beyond 2 years and to identify factors correlating with postoperative valgus instability of unlinked TEA.

METHODS

This study included patients who underwent TEA for rheumatoid arthritis of the elbow at our department between August 2009 and January 2017, with a follow-up period exceeding 2 years. Elbow joint range of motion (ROM) and clinical scores were evaluated preoperatively and at the final follow-up. Factors contributing to valgus instability, such as the Larsen grade, sex, age, side, preoperative ROM, postoperative ROM, implant placement, preoperative carrying angle, and the use of biological disease-modifying antirheumatic drugs (bDMARDs), were also assessed.

RESULTS

This study encompassed 26 elbows from 23 patients, with a mean patient age at surgery of 64.8 years and a mean follow-up duration of 92.4 months. Significant improvements were observed in the ROM (extension: from -31° preoperatively to -21° postoperatively [P = .02], flexion: from 116° to137° [P < .001]), Japanese Orthopaedic Association-Japan Elbow Society Elbow Function Score (from 45.9 to 86.3 points [P < .001]), and Mayo Elbow Performance Score (from 43.6 to 91.7 points [P < .001]). At the last follow-up, 2 elbows exhibited radiolucent lines around the humeral stem, whereas 7 had valgus instability. Factors correlated with valgus instability included total arc at the final follow-up, preoperative carrying angle, and the use of bDMARDs.

DISCUSSION AND CONCLUSION

Unlinked TEA demonstrated favorable midterm outcomes for rheumatoid arthritis of the elbow, albeit with occasional valgus instability. Surgeons should consider preoperative carrying angle and bDMARD use, and exercise caution regarding intraoperative extensions.

Clinical and Radiographic Outcomes of Total Elbow Arthroplasty Using a Semi-constrained Prosthesis with a Triceps-preserving Approach over a Minimum Follow-up Period of 4 Years

OBJECTIVE

Complications related to triceps after total elbow arthroplasty (TEA) have become a major surgical concern. The triceps-preserving approach has the advantage of not disturbing the insertion of triceps but is disadvantaged by the reduced exposure of the elbow joint. The aim of this study was to investigate the clinical and radiological outcomes of TEA with a triceps-preserving approach and to compare the outcomes of TEA to treat arthropathy with that of TEA to treat acute distal humerus fracture.

METHODS

From January 2010 to December 2018, 23 patients undergoing primary TEAs were retrospectively reviewed with a mean follow-up time of 92.6 months (range, 52-136 months). Each TEA was performed using the triceps-preserving approach with a semi-constrained Coonrad-Morrey prosthesis. Patient demographics, range of motion (ROM), pain visual analogue scale (VAS), and triceps strength (Medical Research Council [MRC] scale) were compared before and after surgery. The Mayo Elbow Performance Score (MEPS), Disabilities of the Arm, Shoulder, and Hand (DASH) score, radiographic outcome, and complications were evaluated at follow-up.

RESULTS

In total, seven males and 16 females were included in this study, with a mean age of 66.1 years (range:46-85 years). By the last follow-up, pain had been significantly relieved in all patients. The average MEPS in the arthropathy group and fracture group were 90.8 ± 10.3 points (range: 68-98 points) and 91.7 ± 0.4 (range: 76-100 points), respectively. The average DASH of the arthropathy group and fracture group was 37.3 ± 18.8 points (range: 18-52 points) and 38.4 ± 20.1 (range: 16-60 points). At the last follow-up after surgery, the mean flexion arcs in the arthropathy group and fracture group were 100.4° ± 24.1° and 97.8° ± 28.1°, respectively. The mean pro-supination arcs in the arthropathy group and fracture group were 142.4° ± 15.2° and 139.2° ± 17.5°, respectively. There were no significant differences in clinical outcomes between the two groups (P ≥ 0.05). Triceps strength was normal (MRC grade V) in 15 elbows and good in eight elbows. None of the cases experienced weakness of the triceps strength, infection, periprosthetic fractures, or prosthesis breakage.

CONCLUSIONS

The clinical and radiographical outcomes of TEA with the triceps-preserving approach were satisfactory in patients with distal humerus fracture, osteoarthritis and rheumatoid arthritis.

A Soft-Tissue Landmark to Assess Humeral Component Rotation in Total Elbow Arthroplasty

HYPOTHESIS

Assessing the rotational alignment of the humeral component during total elbow arthroplasty is dependent upon bony landmarks that can be absent or altered in cases of distal humerus fractures, revision arthroplasty, severe bone loss, or deformity. We hypothesize that the intermuscular septum can be used as a reliable soft-tissue landmark to set the rotation of the humeral component intra-operatively when previously described bony landmarks are not reliable or present.

MATERIALS AND METHODS

Forty-eight unpaired cadaveric human subjects (mean age and standard deviation 63 ± 12 years; 24 males, 24 females) underwent computed tomography (CT) scans. The geometric centers of the trochlea and capitellum were assessed, and the line through these two points was set as the flexion-extension axis (FEA) of the elbow. The intermuscular septum axis (IMSA) was drawn proximal to the olecranon fossa and at least 4 cm proximal to the most distal point of the articular surface, where the posterior humeral cortex was flat. The angles between the FEA and IMSA were calculated and compared using a two-tailed t-test. Regression analysis was used to assess the inter- and intra-observer reliability of the IMSA.

RESULTS

The IMSA was externally rotated 10.3° ± 2.8 compared to the FEA (p < 0.001 and confidence interval (CI) of 2.8 with α set to 0.01). The inter- and intra-observer reliability of the IMSA was high, with an R-value of 0.91 and 0.97, respectively.

CONCLUSIONS

The intermuscular septum can be used as a soft-tissue landmark to set humeral component rotation and is 10.3° externally rotated with respect to the FEA of the ulnohumeral joint.

Study of a constrained finite element elbow prosthesis: the influence of the implant placement

BACKGROUND

The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis-bone-cement interface, and evaluate the most wearing working conditions.

MATERIALS AND METHODS

By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element method-FEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexion-extension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by ± 3°.

RESULTS

The greatest von Mises stress state in the bone component for the 90° working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0° and 145° showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90° (- 3° in the sagittal plane, 0° in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement.

CONCLUSION

The areas of greatest stress occur in specific regions of the ulnar and humeral components at the bone-cement-prosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90°. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant.

LEVEL OF EVIDENCE: 5

Distal Humeral Trochlear Geometry Associated With the Spatial Variation of the Dynamic Elbow Flexion Axis

Background: The complexity of the spatial dynamic flexion axis (DFA) of the elbow joint makes the elbow prosthesis design and humeral component alignment challenging. This study aimed to 1) investigate the variations of the spatial DFA during elbow flexion and 2) investigate the relationship between the distal humeral trochlear geometry and the in vivo spatial variation of the DFA.

Methods: Ten healthy subjects participated in this study. Each subject performed a full elbow extension to maximum flexion with hand supination under dual fluoroscopic imaging system (DFIS) surveillance. The 2D fluoroscopic images and the 3D bone models were registered to analyze the in vivo elbow kinematics and DFAs. The spatial DFA positions were defined as inclination with the medial and lateral epicondyle axes (MLA) in the transverse and coronal planes. The range of the DFA positions was also investigated during different flexion phases. The Spearman correlation method was used to analyze the relationship between the distal humeral trochlear’s morphological parameters and the position of DFAs during different flexion phases.

Results: The pathway of the DFAs showed an irregular pattern and presented individual features. The medial trochlear depth (MTD) (r = 0.68, p = 0.03) was positively correlated with the range of the DFA position (2.8° ± 1.9°) in the coronal plane from full extension to 30° of flexion. Lateral trochlear height (LTH) (r = −0.64, p = 0.04) was negatively correlated with the DFA position (−1.4° ± 3.3°) in the transverse plane from 30° to 60° of flexion. A significant correlation was found between LTH with the DFA position in the coronal (r = −0.77, p = 0.01) and transverse planes (r = −0.76, p = 0.01) from 60° to 90° of flexion.

Conclusion: This study showed that the pathway of the dynamic flexion axis has an individual pattern. The medial and lateral trochlear sizes were the key parameters that might affect the elbow joint flexion function. When recovering complex distal humeral fractures or considering the implant design of total elbow arthroplasty, surgeons should pay more attention to the medial and lateral trochlea’s geometry, which may help restore normal elbow kinematics.

Triceps Insufficiency After Total Elbow Arthroplasty: A Systematic Review

BACKGROUND

The incidence of triceps insufficiency after total elbow arthroplasty (TEA) varies in the literature, and a consensus on treatment strategy is lacking. We review the incidence, the risk factors, the clinical presentation, and the diagnosis and treatment of triceps insufficiency after TEA. Based on this information, we have formulated recommendations for clinical practice.

METHODS

We performed a systematic review of the literature from January 2003 to April 2020 to identify studies that investigated triceps function following TEA by searching the PubMed, Cochrane, and Embase databases. Eligible studies (1) reported on triceps function following primary or revision TEA for every indication, regardless of technique (e.g., bone grafts), (2) included ≥6 adult patients, (3) had the full-text article available, and (4) had a minimum follow-up of 1 year.

RESULTS

Eighty studies with a total of 4,825 TEAs were included. The quality was low in 15 studies, moderate in 64 studies, and high in 1 study. The mean incidence of triceps insufficiency was 4.5%. The rates were highest in patients after revision TEA (22%), in those with posttraumatic arthritis as an indication for surgery (10.2%), and after a triceps-reflecting approach (4.9%). Most studies used the Medical Research Council scale to score triceps function, although cutoff points and the definition of triceps insufficiency differed among studies. Surgical treatment showed favorable results with anconeus tendon transfer and Achilles allograft repair when compared with direct repair.

CONCLUSIONS

The incidence of triceps insufficiency varies greatly, probably due to a lack of consensus on the definition of the term. Therefore, we recommend the guidelines for clinical practice that are presented in this article. These guidelines assist clinicians in providing the best possible treatment strategy for their patients and help researchers optimize their future study designs in order to compare outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Prospective cohort study comparing a triceps-sparing and triceps-detaching approach in total elbow arthroplasty: a protocol

BACKGROUND

New surgical approaches have been developed to optimise elbow function after total elbow arthroplasty (TEA). Currently, there is no consensus on the best surgical approach. This study aims to investigate the functional outcomes, prosthetic component position and complication rates after a triceps-sparing and a triceps-detaching approach in TEA.

METHODS AND ANALYSIS

A multicentre prospective comparative cohort study will be conducted. All patients with an indication for primary TEA will enrol in either the triceps-sparing or the triceps-detaching cohort. Primary outcome measure is elbow function, specified as fixed flexion deformity. Secondary outcome parameters are self-reported and objectively measured physical functioning, including triceps force, prosthetic component position in standard radiographs and complications.

DISCUSSION

The successful completion of this study will clarify which surgical approach yields better functional outcomes, better prosthetic component position and lower complication rates in patients with a TEA.

ETHICS AND DISSEMINATION

The Medical Ethics Review Board of University Medical Center Groningen reviewed the study and concluded that it is not clinical research with human subjects as meant in the Medical Research Involving Human Subjects Act (WMO), therefore WMO approval is not needed (METc2019/544).

TRIAL REGISTRATION NUMBER

NTR NL8488.

Triceps on, alignment off? A comparison of total elbow arthroplasty component positioning with a triceps-on and a triceps-off approach

Introduction This retrospective review investigates whether the triceps-on approach obtains alignment of total elbow arthroplasty implants equivalent to a triceps-off approach. Methods The last 30 consecutive total elbow arthroplasties performed by the senior author were reviewed to identify the approach used and pathology treated. Initially, a triceps split and reflection approach was used, then a triceps-preserving approach. Two blinded reviewers measured the component alignment in standardised radiographs. Pearson's correlation coefficient was calculated to investigate inter/intra-observer and error. The two groups were compared using an unpaired Student t-test. Results There were 13 elbows in the triceps-off group and 17 in the triceps-on group. Pearson's coefficient was 0.75 for interobserver error, 0.89 for intra-observer error. There was no statistical difference between the achieved alignment. All ulna components were flexed with a mean angle deviation of 4.5 degrees in the triceps-off group and 5.7 degrees in the triceps on. Two (15%) ulna components in the triceps-off group were placed in over 5 degrees of flexion, compared with seven (44%) in the triceps-on group. Conclusion These results demonstrate no statistical difference in the achieved alignment between the two groups. Surgeons should beware of the tendency to place the ulna component in a flexed position, especially in the triceps-on approach.

Triceps on approach for total elbow arthroplasty: worth preserving? A review of approaches for total elbow arthroplasty

Total elbow arthroplasty can be a rewarding operation and is becoming increasingly used in the elderly fracture population. Multiple approaches are represented in the literature and deciding on the best approach is difficult. This review discusses approaches and their reported outcomes, aiming to allow surgeons to make an informed choice about which approach to use.