Elbow Biomechanics, Radiocapitellar Joint Pressure, and Interosseous Membrane Strain Before and After Radial Head Arthroplasty

Type II coronoid fracture in a terrible triad elbow: An experimental study of the elbow kinematics using dynamic radiostereometric analysis

BACKGROUND

The aim of this study was to evaluate the elbow kinematics with and without a Regan-Morrey type II coronoid fracture in an experimental setting of terrible triad injury with intact collateral ligaments and radial head arthroplasty.

METHODS

Eight human donor arms were examined following radial head arthroplasty with and without a 1/3 coronoid fracture by CT and dynamic radiostereometry during elbow flexion with the forearm in unloaded neutral position, and in supinated- and pronated position without and with 10 N either varus or valgus load, respectively. The elbow kinematics were described using anatomical coordinate systems.

FINDINGS

The coronoid fracture changed the elbow kinematics. In the valgus loaded pronated forearm position, the radius shifted mean 1.7 mm (95 %CI 0.2; 3.2) posterior, and the ulna shifted mean 0.6 mm (95 %CI 0.0; 1.2) in the radial direction. In the unloaded supinated position, the radius shifted 0.8 mm (95 %CI 0.0; 1.5) posterior and 1.0 mm (95 %CI 0.4; 1.6) in the ulnar direction, while the ulna shifted 0.7 mm (95 %CI 0.1; 1.4) posterior. In the varus loaded supinated position, the radius shifted 1.4 mm (95 %CI 0.2; 2.6) in the ulnar direction.

INTERPRETATION

The Regan-Morrey type II coronoid fracture imposed slight kinematic changes to the elbow joint, which may not be clinically relevant. This indicates that a type II coronoid fracture may not need fixation in the setting of optimal radial head arthroplasty with intact collateral ligaments. However, elbow stability should be evaluated intraoperatively in every terrible triad case.

Automated coordinate system estimation: A preliminary step toward computer-assisted radial head arthroplasty planning

The success of radial head arthroplasty (RHA) relies on the design of the implant and precision of the surgical technique, with preoperative planning potentially playing a crucial role. The accurate establishment of a patient-specific anatomical coordinate system (ACS) is essential for this planning process. This study tested the hypothesis that an innovative automated method would be an accurate, reliable, and efficient framework to determine the ACS of the proximal radius, which would be a step toward improving the precision of RHA planning. We used advanced computational techniques to analyze 50 forearm CT scans, comparing the accuracy, reproducibility, reliability, and efficiency of the automated method with manually derived ACS using expert observers as benchmarks. The results showed that the automated approach was more accurate in identifying anatomical landmarks, with smaller mean distance discrepancies (0.6 mm) than manual observers (1 mm). Its reproducibility was also superior, with narrower reproducibility limits, particularly for ulnar notch landmarks (0.6 to 0.8 mm compared to manual selection 1.2 to 1.4 mm) (p = .01). In addition, the limits of agreement and the mean absolute rotational and translational differences of the axes were narrower for the automated method, which also reduced the construction time to an average of 46 s compared to 150 s manually (p < .001). These findings suggest that the automated method has the potential to enhance the accuracy and efficiency of preoperative and postoperative computer-assisted procedures for RHA. Further research is needed to fully understand the utility of this automated system for enhancing RHA computer-assisted surgical planning.

Elbow kinematics with increased lengthening of a radial head arthroplasty evaluated with dynamic radiostereometric analysis

Aims

The aim of this study was to evaluate the kinematics of the elbow following increasing length of the radius with implantation of radial head arthroplasties (RHAs) using dynamic radiostereometry (dRSA).

Methods

Eight human donor arms were examined by dRSA during motor-controlled flexion and extension of the elbow with the forearm in an unloaded neutral position, and in pronation and supination with and without a 10 N valgus or varus load, respectively. The elbows were examined before and after RHA with stem lengths of anatomical size, + 2 mm, and + 4 mm. The ligaments were maintained intact by using a step-cut lateral humeral epicondylar osteotomy, allowing the RHAs to be repeatedly exchanged. Bone models were obtained from CT scans, and specialized software was used to match these models with the dRSA recordings. The flexion kinematics of the elbow were described using anatomical coordinate systems to define translations and rotations with six degrees of freedom.

Results

The greatest kinematic changes in the elbows were seen with the longest, + 4 mm, implant, which imposed a mean joint distraction of 2.8 mm in the radiohumeral joint and of 1.1 mm in the ulnohumeral joint, an increased mean varus angle of up to 2.4° for both the radius and the ulna, a mean shift of the radius of 2.0 mm in the ulnar direction, and a mean shift of the ulna of 1.0 mm posteriorly.

Conclusion

The kinematics of the elbow deviated increasingly from those of the native joint with a 2 mm to a 4 mm lengthening of the radius. This confirms the importance of restoring the natural length of the radius when undertaking RHA.

The role of radial head morphology in proximal radioulnar joint congruency during forearm rotation

Purpose

Congruency of the proximal radioulnar joint (PRUJ) is important in the rotation of the forearm while any compromise would significantly impair the elbow function. The purpose of this study is to determine the morphological features of the radial head and investigate its role in the congruency of the PRUJ during forearm rotation. The hypothesis is that the PRUJ is more congruent in the maximal pronation and supination positions than in the neutral position.

Methods

Thirty sets of computed tomography images of the elbow were acquired, and a three-dimensional model of the proximal radius and ulna was generated. The radius of curvature of the radial head and the radial head at the maximal pronation, neutral positions and maximal supination were calculated and compared with a one-way analysis of variance.

Results

The point on the radial head contacting the middle point of radial head at the maximal pronation and supination was located at the ends of the semi-major axis of the ellipse, while it was located at one end of the semi-minor axis at neutral position. The radii of curvature of the pronation, neutral and supination points of the radial head were 14.72 ± 1.51, 9.74 ± 1.49 and 14.58 ± 1.70 mm, respectively. The value of the neutral point was significantly smaller than that of the pronation and supination points.

Conclusions

This study quantitatively evaluated the morphology of the radial head and suggested that the best congruency of the PRUJ was achieved at maximal pronation and supination, while the neutral position was associated with the least congruency.

Level of Evidence

Basic Science Study.

The Prevalence of Chronic Interosseous Membrane Lesions Following Mason II and III Radial Head Fractures in Complex Elbow Instability-A Retrospective Observational Cohort Study

PURPOSE

The primary aim of the present study was to assess the prevalence of chronic lesions of the central band of the interosseous membrane (cbIOM) in complex elbow instability (CEI) in a consecutive series of patients who had previously undergone surgical treatment for Mason II and III radial head (RH) fractures. The secondary aim was to define its clinical significance.

METHODS

We performed a retrospective study on a prospective database. Our study population comprised 93 patients affected by CEI with type II or III RH fractures according to Mason's classification who were analyzed in the chronic setting. All patients were treated according to the current therapeutic algorithms. At the last follow-up, the "muscular hernia sign" was investigated by means of a bilateral ultrasonographic examination to assess any chronic cbIOM lesions; the Mayo Elbow Performance Score (MEPS) was used to evaluate the clinical significance of these lesions.

RESULTS

All 93 patients were assessed after a mean time of 7.3 years (range: 2-12). No positive "hernia signs" were found, while five patients (5.4%) displayed an increased laxity of the cbIOM when compared with the contralateral side despite a negative "hernia sign". The clinical outcome in all five patients was excellent with a mean MEPS of 96 (range, 90-100).

CONCLUSIONS

Chronic cbIOM lesions are very rare in CEI with RH fractures. No patients in this large sample displayed a cbIOM complete lesion; in cases with increased laxity, satisfactory mid-term clinical results were observed. Considering that previous studies reported (1) a high prevalence of cbIOM lesions in patients with Mason II and III RH fractures and (2) the current expert opinion about the scarce healing potential of the cbIOM, this study also suggests that the IOM may heal better than previously believed when RH fractures are treated appropriately in the acute setting.

Radial head arthroplasty diameter impact on elbow kinematics evaluated by dynamic radiostereometric analysis

Purpose

Radial head arthroplasty (RHA) reestablishes elbow stability after complex radial head fracture, but complication rates are high, possibly due to inappropriate implant sizing. Knowledge of impact of radial head implant diameter on elbow kinematics is limited and warranted. This study evaluated elbow kinematics of different radial head implant diameters after RHA using dynamic radiostereometric analysis (dRSA).

Methods

Eight human donor arms were examined with dRSA during elbow flexion with the forearm in unloaded neutral position, and in supinated- and pronated position without and with 10N either varus or valgus load, respectively. Elbow kinematics were examined before and after RHA with head diameters of anatomical size, -2 mm (undersized), and +2 mm (oversized). The ligaments were kept intact by use of step-cut humerus osteotomy for repeated RHA exchange. Bone models were obtained from CT, and by AutoRSA software bone models were matched with dRSA recordings. The elbow kinematics were described using anatomical coordinate systems.

Results

Compared to the native radial head during elbow flexion, the anatomical sized RHA shifted 2.0 mm in ulnar direction during unloaded pronated forearm position. The undersized RHA shifted 1.5 mm in posterior direction and 2.1 mm in ulnar direction during unloaded pronated forearm position and increased the varus angle by 2.4° during supinated loaded forearm position. The oversized RHA shifted 1.6 mm in radial direction during loaded supinated forearm position.

Conclusions

The anatomically sized RHA should be preferred as it maintained native elbow kinematics the best. The kinematic changes with oversized and undersized RHA diameters were small, suggesting forgiveness for the RHA diameter size.

Level of Evidence

Level III.

Dynamic radiostereometry can objectively quantify the kinematic laxity patterns and rotation instability of the knee during a pivot-shift test

PURPOSE

The pivot-shift test is used to clinically assess knee instability in patients with anterior cruciate ligament (ACL) lesions; however, it has low interobserver reliability. Dynamic radiostereometry (dRSA) is a highly precise and noninvasive method for the objective evaluation of joint kinematics. The purpose of this study was to quantify precise knee kinematics during a pivot-shift test using dRSA imaging.

METHOD

Eight human donor legs, including hemipelvises, were evaluated. Arthroscopic intervention was performed inducing ligament lesions in the ACL, and anterolateral ligament (ALL) section was performed as a capsular incision. The pivot-shift test was recorded with dRSA on knees with intact ligaments, ACL-deficient and ACL + ALL-deficient knees.

RESULTS

A pivot-shift pattern was identifiable after ligament lesion, as a change in tibial posterior drawer velocity from 7.8 mm/s (95% CI: 3.7; 11.9) in ligament intact knees to 30.4 mm/s (95% CI 23.0; 38.8) after ACL lesion to 35.1 mm/s (95% CI 23.4; 46.7) after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm (95% CI 2.1; 3.4) in ligament intact knees to 7.2 mm (95% CI 5.5; 8.9) after ACL lesion to 7.6 mm (95% CI 5.5; 9.8) after combined lesion. A statistically significant increase in tibial external rotation towards the end of the pivot-shift motion was observed when progressing from intact to ACL + ALL-deficient knees (p < 0.023).

CONCLUSION

This experimental study demonstrates the feasibility of dRSA to objectively quantify the kinematic laxity patterns of the knee during the pivot-shift test. The dynamic parameters obtained through dRSA revealed the kinematic changes from ACL to combined ACL-ALL ligament lesion.

LEVEL OF EVIDENCE

Not applicable.

Normal Values of Distal Radioulnar Joint Kinematics during a Dynamic Press Test

Background  Measurement of in vivo distal radioulnar joint (DRUJ) pathomechanics during simple activities can represent the disability experienced by patients and may be useful in diagnostics of DRUJ instability. A first step is to describe the physiological normal limits for DRUJ kinematics in a reproducible and precise test setup, which was the aim of this study. Methods  DRUJ kinematics were evaluated in 33 participants with dynamic radiostereometry (RSA) while performing a standardized press test examination. AutoRSA software was used for image analyses. Computed tomography (CT) forearm bone models were generated, and standardized anatomical axes were applied to estimate kinematic outcomes including, DRUJ translation, DRUJ position ratio, and changes in ulnar variance. Repeatability of dynamic RSA press test double examinations was evaluated to estimate the precision and intraclass correlation coefficient (ICC) test-retest agreement. Results  The maximum force during the press test was 6.0 kg (95% confidence interval [CI]: 5.1-6.9), which resulted in 4.7 mm (95% CI: 4.2-5.1) DRUJ translation, DRUJ position ratio of 0.40 (95% CI: 0.33-0.44), and increase in ulnar variance of 1.1 mm (95% CI: 1.0-1.2). The mean maximum DRUJ translation leveled off after a 5 kg force application. The DRUJ translation ICC coefficient was 0.93 within a prediction interval of ± 0.53mm. Conclusions  This clinical study demonstrates the normal values of DRUJ kinematics and reports excellent agreement and high precision of the press tests examination using an automated noninvasive dynamic RSA imaging method based on patient-specific CT bone models. The next step is the application of the method in patients with arthroscopic verified triangular fibrocartilage complex injuries. Level of Evidence  This is a Level IV, case series study.

Survivorship of anatomic press-fit short-stem radial head replacement with a pyrocarbon bearing

BACKGROUND

Restoring the radial head as a stabiliser of the elbow is considered important in cases where there is an associated bony or ligamentous injury. A variety of radial head prostheses are available. There are no reports of the survivorship of a short-stem press-fit radial head prostheses with pyrocarbon bearing.

PATIENTS AND METHODS

With institutional review board approval, a retrospective case-note analysis was performed of a consecutive single-surgeon case series of the Integra LifeScience pyrocarbon radial head prostheses (Carbon Modular Radial Head) from October 2010 to October 2019 in a tertiary referral centre. The series was divided into acute trauma and salvage cohorts. Kaplan-Meier survivorship analysis was conducted.

RESULTS

36 patients were included, 23 (64%) for acute injuries and 13 (36%) for failed initial treatment. Of the acute injuries, 20 (87%) had a Wrightington type-C elbow fracture-dislocation. Reoperation was performed in 4 (11%) patients; 10 (28%) had possible loosening on radiographs. The implant survival rate was 94% at shortest follow-up of 17 months (mean 70 months).

DISCUSSION

Treatment of complex radial head fractures using a pyrocarbon-bearing, anatomic press-fit design provides satisfactory short-term survivorship in this case series. The implant should be used with caution in salvage cases, due to higher rates of loosening seen in this cohort.

Radial head arthroplasty vs. open reduction and internal fixation for the treatment of terrible triad injury of the elbow: A systematic review and meta‑analysis update

Terrible triad injury of the elbow (TTIE) is a severe high-energy injury to the elbow, mainly including elbow dislocation, coronoid fracture and radial head fracture. It is difficult to maintain the stability of the elbow joint using traditional conservative treatment, and there is a high risk of redislocation and various complications. Therefore, surgical treatment is currently advocated, mainly for repairing damaged ligaments and reconstructing bony structures, but there is still controversy about the treatment plan for the radial head. The current meta-analysis was conducted to compare the differences in efficacy of radial head arthroplasty (RHA) and open reduction internal fixation (ORIF) in the treatment of TTIE. Published literature related to the treatment (either ORIF or RHA) of TTIE was searched for in Embase, PubMed, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, ProQuest Dissertations and Theses, Cochrane Library and Chinese Biomedical Literature Database. According to the search strategy, a total of 1,928 related publications were retrieved. The patient must have been diagnosed with TTIE and required surgery on the radial head. The interventions were RHA and ORIF. Non-case-control studies, case reports, review articles, letters, duplicate reports and literature without sufficient relevant data were excluded. The quality of the literature was evaluated according to the Cochrane systematic review methodology and the Jadad scale. After data extraction, meta-analysis was performed using ReviewManager 5.4 software (Cochrane). A total of 15 studies involving 455 patients (189 who underwent RHA and 266 who underwent ORIF) were included. Range of motion (ROM) of the forearm (pronation-supination arc) after surgery in the RHA group [95% CI (0.28, 9.59); P=0.04] was found to be significantly superior to the ORIF group, with a lower incidence of complications [95% CI (0.22, 0.84); P=0.01]. However, there was no statistically significant difference for the Mayo Elbow Performance Score, Disabilities of the Arm, Shoulder and Hand Score nor for ROM of the elbow (flexion-extension arc). Overall, compared with the ORIF group, the RHA group had better forearm rotational ROM and fewer complications after surgery. Therefore, RHA was found to be superior to ORIF in the treatment of TTIE.

Patients with knee osteoarthritis can be divided into subgroups based on tibiofemoral joint kinematics of gait - an exploratory and dynamic radiostereometric study

OBJECTIVE

Patients with advanced knee osteoarthritis (KOA) frequently alter their gait patterns in an attempt to alleviate symptoms. Understanding the underlying pathomechanics and identifying KOA phenotypes are essential to improve treatments. We investigated kinematics in patients with KOA to identify subgroups of homogeneous knee joint kinematics.

METHOD

A total of 66 patients with symptomatic KOA scheduled for total knee arthroplasty and 15 age-matched healthy volunteers with asymptomatic, non-arthritic knees were included. We used k-means clustering to divide patients into subgroups based on dynamic radiostereometry-assessed tibiofemoral joint kinematics. Clinical characteristics such as knee ligament lesions and KOA scores were graded by magnetic resonance imaging and radiographs, respectively.

RESULTS

We identified four clusters that were supported by clinical characteristics. The flexion group (n = 20) consisted primarily of patients with medial KOA. The abduction group (n = 17) consisted primarily of patients with lateral KOA. The anterior draw group (n = 10) was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the highest KOA score. The external rotation group (n = 19) primarily included patients with medial collateral and posterior cruciate ligament lesions.

CONCLUSION

Based on tibiofemoral gait patterns, patients with advanced KOA can be divided into four subgroups with specific clinical characteristics and different KOA-affected compartments. The findings add to our understanding of how knee kinematics may affect the patient's development of different types of KOA. This may inspire improved and more patient-specific treatment strategies in the future.

Radiocapitellar joint pressures following transradial amputation increase during elbow motion

This study aimed to compare the contact area, mean pressure, and peak pressure of the radiocapitellar joint (RCJ) in the upper limb after transradial amputation with those of the normal upper limb during elbow flexion and forearm rotation. Testing was performed using ten fresh-frozen upper limbs, and the transradial amputation was performed 5 cm proximal to the radial styloid process. The specimens were connected to a custom-designed apparatus for testing. A pressure sensor was inserted into the RCJ. The biomechanical indices of the RCJ were measured during elbow flexion and forearm rotation in all specimens. There was no significant difference in the contact area between the normal and transradial amputated upper limbs. However, in the upper limbs after transradial amputation, the mean pressure was higher than that in the normal upper limbs at all positions of elbow flexion and forearm rotation. The peak pressure was significantly higher in the upper limbs after transradial amputation than in the normal upper limbs, and was especially increased during pronation at 45° of elbow flexion. In conclusion, these results could cause cartilage erosion in the RCJ of transradial amputees. Thus, methods to reduce the pressure of the RCJ should be considered when a myoelectric prosthesis is developed.

Assessment of knee kinematics with dynamic radiostereometry: Validation of an automated model-based method of analysis using bone models

Radiostereometic analysis (RSA) is a precise method for the functional assessment of joint kinematics. Traditionally, the method is based on tracking of surgically implanted bone markers and analysis is user intensive. We propose an automated method of analysis based on models generated from computed tomography (CT) scans and digitally reconstructed radiographs. The study investigates method agreement between marker-based RSA and the CT bone model-based RSA method for assessment of knee joint kinematics in an experimental setup. Eight cadaveric specimens were prepared with bone markers and bone volume models were generated from CT-scans. Using a mobile fixture setup, dynamic RSA recordings were obtained during a knee flexion exercise in two unique radiographic setups, uniplanar and biplanar. The method agreement between marker-based and CT bone model-based RSA methods was compared using bias and LoA. Results obtained from uniplanar and biplanar recordings were compared and the influence of radiographic setup was considered for clinical relevance. The automated method had a bias of -0.19 mm and 0.11° and LoA within ±0.42 mm and ±0.33° for knee joint translations and rotations, respectively. The model pose estimation of the tibial bone was more precise than the femoral bone. The radiographic setup had no clinically relevant effect on results. In conclusion, the automated CT bone model-based RSA method had a clinical precision comparable to that of marker-based RSA. The automated method is non-invasive, fast, and clinically applicable for functional assessment of knee kinematics and pathomechanics in patients.