Radial shortening osteotomy reduces radiocapitellar contact pressures while preserving valgus stability of the elbow

Arthroscopic matched osteoplasty of the radial head for painful radiocapitellar osteoarthritis: surgical technique and case series

BACKGROUND

Radiocapitellar arthritis can cause pain, loss of motion, and impaired elbow function. Current surgical treatment options are limited. We have developed an original and simple surgical technique to address this, called arthroscopic matched osteoplasty of the radial head (AMOR). In AMOR, the radial head is partially resected and recontoured to match the capitellum and decompress the degenerate radiocapitellar articulation while preserving the ulnohumeral articulation where the cartilage is usually well preserved.

METHODS

Indications and the surgical technique of the AMOR procedure are described. A retrospective observational service evaluation study was conducted from electronic patient records. Collected clinical outcomes included range of motion, pain level, subjective functional score, and general satisfaction with the results of the procedure. The radiographic outcome was radiocapitellar joint space.

RESULTS

Between 2017 and 2021, eight consecutive patients underwent AMOR as part of an arthroscopic osteocapsular arthroplasty procedure. Radiographically, the mean radiocapitellar joint space improved from an average of 1.7 mm to 4.6 mm. Clinically, the mean pain score decreased from 8/10 to 3/10. Six of the eight patients (75%) were satisfied with their results. In two cases, initial improvement following surgery lasted less than 1 year, and one of these patients underwent total elbow arthroplasty for painful ulnohumeral osteoarthritis. There were no complications of surgery recorded.

CONCLUSIONS

AMOR is a safe treatment option for painful radiocapitellar osteoarthritis and can be incorporated as an "add-on" procedure by surgeons performing elbow osteocapsular arthroplasty in cases with a positive grip and grind test and radiographic evidence of radiocapitellar OA. Level of evidence: IV.

Digital smart internal fixation surgery for coronal process basal fracture with normal joint spaces or radius-shortening: Occult factor of radius-ulna load sharing

BACKGROUND

Reasonable postoperative humeroradial and humeroulnar joint spaces maybe an important indicator in biomechanical stability of smart internal fixation surgery for coronoid process basal fractures (CPBF). The aim of this study is to compare elbow articular stresses and elbow-forearm stability under smart internal fixations for the CPBF between normal elbow joint spaces and radius-shortening, and to determine the occult factor of radius-ulna load sharing.

METHODS

CT images of 70 volunteers with intact elbow joints were retrospectively collected for accurate three-dimensional reconstruction to measure the longitudinal and transverse joint spaces. Two groups of ten finite element (FE) models were established prospectively between normal joint space and radius-shortening with 2.0 mm, including intact elbow joint and forearm, elbow-forearm with CPBF trauma, anterior or posterior double screws-cancellous bone fixation, mini-plate-cancellous bone fixation. Three sets of physiological loads (compression, valgus, varus) were used for FE intelligent calculation, FE model verification, and biomechanical and motion analysis.

RESULTS

The stress distribution between coronoid process and radial head, compression displacements and valgus angles of elbow-forearm in the three smart fixation models of the normal joint spaces were close to those of corresponding intact elbow model, but were significantly different from those of preoperative CPBF models and fixed radius-shortening models. The maximum stresses of three smart fixation instrument models of normal joint spaces were significantly smaller than those of the corresponding fixed radius-shortening models.

CONCLUSIONS

On the basis of the existing trauma of the elbow-forearm system in clinical practice, which is a dominant factor affecting radius-ulna load sharing, the elbow joint longitudinal space has been found to be the occult factor affecting radius-ulna load sharing. The stability and load sharing of radius and ulna after three kinds of smart fixations of the CPBF is not only related to the anatomical and biomechanical stability principles of smart internal fixations, but also closely related to postoperative elbow joint longitudinal space.

Biomechanical study of the effect of traction on elbow joint capsule contracture

Dynamic orthoses have a significant effect on the treatment of elbow capsular contracture. Because of the lack of quantitative research on traction forces, determining the appropriate traction force to help stretch soft tissues and maintain the joint's range of motion is a challenge in the rehabilitation process. We developed a human elbow finite element (FE) model incorporating the activity behavior of the muscles and considering different capsular contracture locations, including total, anterior and posterior capsular contractures, to analyze the internal biomechanical responses of different capsular contracture models during flexion (30 to 80 degrees). Traction loads of 10, 20, 30 and 40 N were applied to the ulna and radius at the maximum flexion angle (80 degrees) to explore the appropriate traction loads at week 4 after a joint capsule injury. We observed a significant increase in posterior capsule stress with anterior capsular contracture (ACC), and the maximum peak stress was 1.3 times higher than that in the healthy model. During the fourth week after elbow capsule injury, the appropriate traction forces for total capsule contracture (TCC), ACC and posterior capsule contracture (PCC) were 20, 10 and 20 N, respectively; these forces maintained a stable biomechanical environment for the elbow joint and achieved a soft tissue pulling effect, thus increasing elbow mobility. The results can be used as a quantitative guide for the rehabilitation physicians to determine the traction load for a specific patient.

A combined experimental and finite element analysis of the human elbow under loads of daily living

Elbow trauma is often accompanied by a loss of independence in daily self-care activities, negatively affecting patients' quality of life. Finite element models can help gaining profound knowledge about native human joint mechanics, which is crucial to adequately restore joint functionality after severe injuries. Therefore, a finite element model of the elbow is required that includes both the radio-capitellar and ulno-trochlear joint and is subjected to loads realistic for activities of daily living. Since no such model has been published, we aim to fill this gap. For comparison, 8 intact cadaveric elbows were subjected to loads of up to 1000 N, after they were placed in an extended position. At each load step, the displacement of the proximal humerus relative to the distal base plate was measured with optical tracking markers and the joint pressure was measured with a pressure mapping sensor. Analogously, eight finite element models were created based on subject-specific CT scans of the corresponding elbow specimens. The CT scans were registered to the positions of tantalum beads in the experiment. The optically measured displacements were applied as boundary conditions. We demonstrated that the workflow can predict the experimental contact pressure distribution with a moderate correlation, the experimental peak pressures in the correct joints and the experimental stiffness with moderate to excellent correlation. The predictions of peak pressure magnitude, contact area and load share on the radius require improvement by precise representation of the cartilage geometry and soft tissues in the model, and proper initial contact in the experiment.

Anatomical and Biomechanical Stability of Single/Double Screw-Cancellous Bone Fixations of Regan-Morry Type III Ulnar Coronoid Fractures in Adults: CT Measurement and Finite Element Analysis

OBJECTIVE

At present, it is still uncertain whether single screw has the same stability as double screws in the treatment of ulnar coronal process basal fracture (Regan-Morry type III). So, we aimed to compare the pull-out force and anti-rotation torque of anterior single/double screw-cancellous bone fixation (aSSBF, aDSBF) in this fracture, and further study the influencing factors on anatomical and biomechanical stability of smart screw internal fixations.

METHODS

A total of 63 adult volunteers with no history of elbow injury underwent elbow CT scanning with associated three-dimensional reconstruction that enabled the measurements of bone density and fixed length of the proximal ulna and coronoid. The models of coronal process basal fracture, aSSBF and aDSBF, were developed and validated. Using the finite element model test, the sensitivity analysis of pull-out force and rotational torque was carried out.

RESULTS

The pull-out force of aSSBF model was positively correlated with the density of the cancellous bone and linearly related to the fixed depth of the screw. The load pattern of pull-out force of aDSBF model was similar to that of aSSBF model. The ultimate torque of aDSBF model was higher than that of aSSBF model, but the load pattern of ultimate torque of both models was similar to each other when the fracture reset was satisfactory, and the screw nut attaches closely to coronoid process. Moreover, with enhancement of initial pre-tightening force, the increase of ultimate torque of both models was small.

CONCLUSIONS

In addition to three pull-out stability factors of smart screw fixations, fracture surface fitting degree and nut fitting degree are the other two important anatomical and biomechanical stability factors of smart screw fixations both for rotational stability. When all pull-out stability and rotational stability factors meet reasonable conditions simultaneously, single or double screw fixation methods are stable for the treatments of ulnar coronoid basal fractures.

Impact of radiocapitellar interposition arthroplasty on ulnohumeral joint biomechanics

BACKGROUND

Radial head excision (RHE) has been shown to increase contact pressures within the ulnohumeral joint. Radiocapitellar interposition arthroplasty (RCIA) with the use of a soft tissue graft is an alternative for the treatment of isolated radiocapitellar arthritis or with failure of radial head replacement. We investigated contact pressures and contact area within the ulnohumeral joint after RHE compared to RCIA with dermal autograft.

METHODS

Six fresh-frozen cadaver elbows were tested on a custom dynamic elbow frame. A pressure sensor was inserted into the intact elbow joint, and mean contact pressure, peak contact pressure, contact area, and force within the ulnohumeral joint were recorded at 0°, 30°, 60°, 90°, and 120° of flexion as a valgus load was applied to the elbow. The radial head was then excised and specimens were retested. Finally, a dermal graft matched to the size of the resected radial head was inserted in the radiocapitellar space and the specimens were tested a third time.

RESULTS

At 90° of flexion, contact pressure within the ulnohumeral joint was significantly lower with RCIA compared with RHE (110.8 kPa vs 216.8 kPa; P = .013). The mean peak contact pressure was also significantly lower with RCIA compared with RHE at 90° (279.4 vs 626.7 kPa; P = .025). No statistically significant differences were seen in mean contact area or force between the 3 testing conditions at any flexion position.

CONCLUSION

RCIA with a dermal graft reduced contact pressures within the ulnohumeral joint compared to RHE at 90° of flexion without a significant change in contact area or contact force.

Overlengthening of the radial column in radial head replacement: a review of the literature and presentation of a classification system

BACKGROUND

Radial head arthroplasty is a common procedure in elbow surgery. It has been shown to be of benefit for the patients, but there also are relevant complications that should be prevented if possible. One significant complication is overlengthening of the radial head prosthesis. In overlengthening, the head of the prosthesis overextends the physiological level of the native radial head and leads to overcompression in the radiohumeral joint. Rapid erosion and arthritic changes may then impede the clinical outcome. The incidence of overlengthening is not precisely known, but estimations range to up to 20% of all implanted prostheses.

METHODS

The present review discusses the available body of literature on overlengthening and lines out a classification system that may be used to guide treatment algorithms. The classification is based on the personal experiences of the author during their clinical practice.

RESULTS

In low-grade overlengthening (type I) conservative treatment can be an option. In Types II-IV usually revision surgery is needed. Depending on the state of the capitulum and joint stability, it is possible re-implant a prosthesis, or rely on implant removal alone.

DISCUSSION

The present review aimed at shedding light into overlengthening as a complication radial head replacement and to help identify and treat it.

Surgical revision of radial head fractures: a multicenter retrospective analysis of 466 cases

BACKGROUND

Radial head fractures lead to persisting disability in a considerable number of cases. This study aimed to investigate their most common revision causes and procedures.

METHODS

This multicenter retrospective study reviewed the cases of 466 adult patients who had undergone surgical revision after operative or nonoperative treatment of a radial head fracture. The initial diagnosis was a Mason type I fracture in 13.0%, Mason type II fracture in 14.6%, Mason type III fracture in 22.8%, Mason type IV fracture in 20.9%, terrible-triad injury in 12.8%, Monteggia-like lesion in 13.1%, and Essex-Lopresti lesion in 2.0%. Initial treatment was nonoperative in 30.2%, open reduction and internal fixation (ORIF) in 44.9%, radial head arthroplasty in 16.6%, radial head resection in 3.7%, sole treatment of concomitant injuries in 2.6%, and fragment excision in 2.0%. Up to 3 revision causes and procedures were recorded per case.

RESULTS

The most common complications were stiffness (67.4%), instability (36.5%), painful osteoarthritis (29.2%), ORIF related (14.8%), nonunion or necrosis (9.2%), radial head arthroplasty related (7.5%), ulnar neuropathy (6.0%), and infection (2.6%). Revision procedures frequently included arthrolysis (42.1%), arthroplasty (24.9%), implant removal (23.6%), ligament repair or reconstruction (23.0%), débridement (14.2%), repeated ORIF (8.2%), and/or radial head resection (7.7%). Mason type I or II fractures were primarily revised because of stiffness and painful osteoarthritis. Complications after Mason type III fractures were predominantly ORIF related. Fracture-dislocations showed a wide range of complications, with instability and stiffness comprising the most common causes of revision.

CONCLUSIONS

The complications of radial head fractures are characteristic to their classification. Knowledge of these findings might guide surgeons in treating these injuries and may help counsel patients accordingly.

A combination of an anteromedial, anterolateral and midlateral portals is sufficient for 360° exposure of the radial head for arthroscopic fracture fixation

PURPOSE

Arthroscopic fixation of radial head fractures is an alternative to open reduction and internal fixation; the latter, however, presents the advantage of minimal soft-tissue damage. The exposure of the radial head for adequate screw placement can be technically challenging. The aim of this study was to evaluate the inter-observer agreement on the effective contact arc in the axial plane of the radial head of three different elbow arthroscopy portals.

METHODS

A fresh-frozen cadaver specimen was obtained and prepared in an arthroscopic setting. Standard anterolateral (AL), anteromedial (AM), and midlateral (ML) portals were established and a circular reference system was marked on the radial head. Ten orthopaedic surgeons were then asked to move the forearm from maximal supination to maximal pronation and indicate with a Kirschner wire from each portal the extension in which they would feel confident in placing a cannulated screw passing through the centre of the articular plane of the radial head (axial contact arc). The Shapiro-Wilk normality test was used to evaluate the normal distribution of the sample. A coefficient of variation (CoV) was calculated to determine agreement among observers.

RESULTS

The average arc of axial contact arc that could be contacted from the AM portal measured 150 ± 14.1°, or 41.7% of the radial head circumference; the one from the AL portal measured 257 ± 29.5°, or 71.4% of the radial head circumference; that from the ML portal measured 212.5 ± 32.6°, or 59.0% of the radial head circumference. Considering all three portals, the whole radial head circumference could be contacted. The AM portal showed the smallest CoV (9.4%) as compared to the AL (11.5%), and the ML (15.3%) portals.

CONCLUSIONS

With an appropriate use of the standard AL, AM, and ML portals, the whole radial head circumference can be effectively exposed for adequate fixation of radial head fractures. The contact arc of the AM portal presents the smallest variability among different observers and the AL portal shows a superiority in axial contact arc. This information is important for pre-operative planning, and helps to define the limits of arthroscopic radial head fracture fixation.