Bridge Plating is an Effective Adjunct Treatment for Complex Elbow Instability

BACKGROUND

Managing persistent elbow instability and chronic dislocations presents challenges despite traditional treatments. Supplementary methods like immobilization and various fixations, though common, can carry high complication rates. This study assesses the efficacy of bridge plating in treating complex elbow instability through a retrospective review of patients. Data on characteristics, treatment duration, range of motion, complications, and evaluation scores were analyzed, providing insights into outcomes complications associated with bridge plating.

RESULTS

Eleven patients were reviewed at an average follow-up of 80 ± 68 weeks. postoperatively. The average age was 53±14 years and there were 5 females and 6 males. The average BMI was 38. Bridge plating was used for a spectrum of complex elbow injuries. The average time from injury to bridge plating in acute cases was 29±19 days and 344±381 days in chronic cases. The average duration of bridge plating was 121 ± 72 days. At the time of plate removal, mean intraoperative elbow motion was extension 58±12°, flexion 107±14°, supination 66±23° and pronation 60±26°. At the latest follow-up visit, average elbow motion was extension 37±22°, Flexion 127± 17°, supination 72±15° and pronation 63±18°. There were 6 complications (55%); heterotopic ossification, ulnar neuropathy, wound failure over the plate in a thin patient, an ulnar shaft peri-prosthetic fracture due to a seizure induced fall, and elbow subluxation despite bridge plate fixation. One patient sustained a fracture of a 3.5mm locking bridge plate. One patient required a contracture release for persistent stiffness. Four of these complications can be directly attributed to the use of the bridge plate (36%). At final follow-up, the average patient rated elbow evaluation score was 34, with 0 indicating no pain and disability. The average single assessment numeric evaluation score was 66% for the 8 patients who had this available, with 100% being the best possible attainable score.

CONCLUSION

Bridge plating effectively maintains joint reduction in selected complex elbow instability cases. However, patients with bridge plates often require a second surgery for removal and experience high rates of general complications due to the complexity of their condition.

Morphology of Proximal Ulna Bare Area: A Guide for Olecranon Osteotomy

PURPOSE

Olecranon osteotomy is commonly used to obtain access to the distal humerus for fracture fixation. The goal of this study was to accurately describe the anatomy of the bare area to minimize articular cartilage damage while performing olecranon osteotomies.

METHODS

Twenty cadaveric ulnae were denuded to expose the bare area. Laser surface mapping was used to create 3-dimensional models, and the nonarticular portions of the ulnae were digitally measured.

RESULTS

The morphology of the bare area from all aspects of the proximal ulna was defined. The central bare area was consistent in its location, 4.9 ± 1.5 mm distal to the deepest portion of the trochlear notch and 23.2 ± 2.3 mm distal to the olecranon tip. The maximum chevron osteotomy apical angle to stay within the bare area averaged 110° ± 11.8°. However, there was little tolerance for error without the risk of violating the articular cartilage. With transverse osteotomy, averaging 18° ± 10.6° in the coronal plane, there is less risk of damaging the articular cartilage.

CONCLUSIONS

Transverse osteotomy perpendicular to the posterior surface of the ulna aiming at the visible bare area on the medial and lateral sides of the greater sigmoid notch may reduce the chances of violating the nonvisible articular cartilage of the proximal ulna. Based on the findings of this study, if chevron osteotomy is used, a shallow apex distal angle of more than 110° is recommended.

CLINICAL RELEVANCE

This study provides intraoperative landmarks to guide surgeons performing olecranon osteotomies to stay within the bare area.

The effect of lateral collateral ligament repair tension on elbow stability: An in vitro biomechanical study

BACKGROUND

The aim of this study was to determine the optimal repair tension of the lateral collateral ligament of the elbow by performing simulated active flexion with the arm in the varus gravity loaded position using an in vitro elbow simulator.

METHODS

Eight cadaveric specimens were mounted in the varus gravity loaded orientation onto an elbow motion simulator. Four states were studied (intact, lateral collateral ligament injured, and 15 N and 20 N lateral collateral ligament repairs) with the forearm in supination and pronation. An electromagnetic tracking system was used to measure joint kinematics during active elbow flexion.

FINDINGS

There was no difference in ulnohumeral rotation between the intact state and the 15 N repair (P = .150 for pronation; P = 1.0 for supination) or the 20 N repair (P = 1.0 for pronation; P = .568 for supination). For varus-valgus angulation, the 20 N repair was not statistically different from the intact state (P = .059 in pronation; P = 1.0 in supination).

INTERPRETATION

Repair of the lateral collateral ligament following injury can restore joint kinematics with the arm in the varus position. A repair tension of 20 N was successful in restoring joint stability for simulated active motion with the forearm in pronation and supination. This study shows that when the lateral collateral ligament is repaired with adequate tension, avoidance of the varus position may not be as crucial during early motion.

Indomethacin for Heterotopic Ossification Prophylaxis Following Surgical Treatment of Elbow Trauma: A Randomized Controlled Trial

INTRODUCTION

Heterotopic ossification is a frequent complication following surgical treatment of elbow trauma. The use of indomethacin to prevent heterotopic ossification is reported in the literature, however, its effectiveness is controversial. The purpose of this randomized, double blind, placebo-controlled study was to determine if indomethacin is effective in reducing the incidence and severity of heterotopic ossification after surgical management of elbow trauma.

METHODS

Between February 2013 and April 2018, 164 eligible patients were randomized to receive postoperative indomethacin or placebo medications. The primary outcome was to determine the incidence of heterotopic ossification on elbow radiographs at one year follow-up. Secondary outcomes included the Patient Rated Elbow Evaluation (PREE), the Mayo Elbow Performance Index (MEPI) and the Disabilities of the Arm, Shoulder and Hand (DASH). Range of motion, complications and non-union rates were also obtained.

RESULTS

At one year follow-up, there was no significant difference in the incidence of heterotopic ossification in the indomethacin group (49%) compared to the control (55%) group (relative risk = 0.89; p = 0.52). There were no significant differences in postoperative PREE, MEPI, DASH scores or range of motion (p = 0.16). There was a 17% complication rate in both the treatment and control groups (p = 1). There were no non-unions in either group.

CONCLUSION

This level 1 study demonstrated that indomethacin prophylaxis against heterotopic ossification in surgically treated elbow trauma was not significantly different than placebo.

Recovery Trajectories Following Complex Elbow Injuries and Radial Head Arthroplasty: A Longitudinal Study Over 8 Years

PURPOSE

Radial head arthroplasty (RHA) is commonly performed to manage comminuted unreconstructible radial head fractures. Although the outcomes of RHA are often satisfactory, revisions are usually considered when pain intensity is higher than expected. Therefore, it is important to investigate the recovery trajectories of patients following RHA over an extended period and the characteristics that may lead to unfavorable outcomes.

METHODS

The Patient-Rated Elbow Evaluation (PREE) was used to assess recovery in 94 patients at baseline (within 2-7 days after surgery); 3 and 6 months; and 1, 2, 3, 4, 5, and 8 years after RHA. Lower PREE values indicate lower pain and disability. Latent growth curve analysis was used to determine classes of recovery. The characteristics of the participants in the identified recovery trajectory classes were then compared.

RESULTS

Two distinct recovery trajectories were identified: optimal and suboptimal recoveries. Most patients (84%) belonged to the optimal recovery class, which exhibited significantly lower baseline PREE scores, a consistent pattern of recovery, and a relatively high rate of change. Patients in the suboptimal recovery class (16%) had significantly higher baseline PREE scores and continued to experience relatively higher levels of pain and disability for the duration of the study; their rate of recovery was much slower. Patients belonging to the 2 recovery trajectories did not differ based on age or sex. Although we had low power in other variables, a qualitative exploration showed that the number of current or previous smokers was higher in the suboptimal recovery trajectory class.

CONCLUSIONS

In this longitudinal cohort study, we show that high postsurgical pain and disability, and potentially smoking, may adversely affect the recovery trajectory following RHA. Clinicians are recommended to assess these potential factors while considering revision surgeries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Overhead arm positioning in the rehabilitation of elbow dislocations: An in vitro biomechanical study

STUDY DESIGN

In vitro biomechanical study.

INTRODUCTION

Elbow stiffness is a common complication following elbow dislocation. Overhead exercises have been proposed to initiate early motion to reduce stiffness through employing gravity to stabilize the elbow. The implications of this position with regard to elbow kinematics after dislocation have not been reported.

PURPOSE OF THE STUDY

To determine the influence of the overhead position on elbow stability following combined medial and lateral collateral ligament (MCL and LCL) injuries.

METHODS

Passive and simulated active extension were performed on 11 cadaveric elbows with the arm in the overhead, dependent, and horizontal positions and with the forearm in pronation, neutral, and supination. Internal-external rotation (IER) and varus-valgus angulation (VVA) of the ulnohumeral joint were assessed for the intact elbow and after simulated MCL-LCL injury. Repeated-measures analyses of variance were conducted to analyze the effects of elbow state, arm position, forearm rotation, and extension angle.

RESULTS

During passive extension with the arm overhead, the pronated position resulted in more internal rotation than supination (-2.6 ± 0.7°, P = .03). There was no effect of forearm rotation on VVA. The overhead position increased internal rotation relative to the dependent position when the forearm was neutral (-8.5 ± 2.5°, P = .04) and relative to the horizontal position when the forearm was supinated (-12.7 ± 2.2°, P= .02). During active extension, pronation increased valgus angle compared to the neutral (+1.2 ± 0.3°, P= .04) and supinated (+1.5 ± 0.4°, P= .03) positions, but did not affect IER. There was no difference between active and passive motion with the arm overhead (P > .05).

DISCUSSION

Movement of the injured elbow in the overhead position most closely replicated kinematics of the intact elbow compared to the other arm positions.

CONCLUSIONS

Overhead elbow extension results in similar kinematics between an intact elbow and an elbow with MCL and LCL tears. As such, therapists might consider early motion in this position to reduce the risk of elbow stiffness after dislocation.

Outcomes of radial head implants in total elbow arthroplasty

BACKGROUND

There is no consensus on the management of the radial head in total elbow arthroplasty (TEA). In 3-part TEA designs, options include radial head retention, excision, or arthroplasty. Biomechanical studies suggest improved varus-valgus stability with radial head implants in unlinked total elbows. Unfortunately, complications with radial head implants have been common with historical designs. The aim of this study was to evaluate the clinical and radiographic outcomes of radial head implants in a current 3-part TEA and identify risk factors for mechanical failure.

METHODS

We performed a retrospective review of radial head implants with a 3-part convertible TEA from 2001 to 2016. Clinical outcomes, functional scores, and radiographic outcomes were recorded. The preoperative radiocapitellar alignment was measured using the radiocapitellar ratio (RCR). Statistics include descriptive statistics, t tests, logistic regression, and Kaplan-Meier survival curves.

RESULTS

We identified 44 TEAs in 40 patients, with a mean follow-up period of 7.2 years. The average age at surgery was 58 ± 11 years; 80% of the TEAs were performed in women. The indication for surgery was rheumatoid arthritis in 86%; of the implants, 61% were unlinked. The average preoperative RCR was 10.7 ± 17.9. Postoperatively, 2 radial head implants (5%) were subluxated, 6 (14%) were dissociated, and 2 (5%) were dissociated with implant dislocation on radiographic review. The revision rate for radial head subluxation, dissociation, or dislocation was 7% (n = 3). Univariate logistic regression showed that male sex (P = .002), abnormal preoperative RCR (P = .02), linked implant (P = .03), and older age (P = .04) were risk factors for radial head subluxation, dissociation, or implant dislocation. A multivariate model with all 4 variables did not demonstrate statistical significance.

CONCLUSION

The incidence of radial head arthroplasty subluxation, dissociation, or implant dislocation was high (23%). In a univariate logistic regression model, male sex, abnormal preoperative RCR, and linked implants were all statistically significant risk factors for mechanical failure of the radial head implant. Our multivariate model did not show any statistically significant independent risk factors. Polyethylene wear or loosening of the radial head implants was not observed in this study; failure of the bipolar linkage was the principal mode of failure. Although further study is required, caution should be used when considering inserting a radial head implant in male patients with significant preoperative radiocapitellar malalignment. Radial head subluxation or dissociation is not an absolute indication for revision in an asymptomatic patient. Improvements in radial head implant designs in TEA are needed.

Computed tomography analysis of the relationship between the coronoid and the radial head

BACKGROUND

The coronoid process is an important stabilizer of the elbow, and its anatomy has been extensively studied. However, data documenting the relationship of the coronoid relative to the radial head (RH) are limited. The latter is a good landmark for the surgeon when débriding or reconstructing the coronoid. This imaging-based study quantified the anatomic relationship between the coronoid and the proximal radius and ulna.

METHODS

We investigated 80 cadaveric upper extremities (18 paired elbows) by 3-dimensional digital analysis of computed tomography data. After construction of a standardized coordinate system, the relationships between the coronoid, the anterior-most point of the RH, the deepest point of the articular surface of the RH, the top of the lesser sigmoid notch, and the deepest point of the guiding ridge of the trochlear notch were analyzed.

RESULTS

The mean height of the tip of the coronoid was 36 ± 4 mm (range, 26-43 mm). The mean height of the anterior-most point of the RH was 40 ± 4 mm (range, 28-47 mm). The mean distance between the tip of the coronoid and the anterior-most point of the RH was 4.5 ± 1 mm (range, 2-10 mm). For paired elbows, the heights of the tip of the coronoid and the anterior-most point of the RH were similar between sides.

CONCLUSION

This study described the relationship between the coronoid and RH. This information should prove useful when reconstructing a coronoid from a medial approach in the case of an intact RH. The difference in radiographic height between the tip of the coronoid and anterior RH in the normal elbow averages 5 mm. However, when we account for the normal cartilage thickness of the RH and coronoid, a 3- to 6-mm difference in height would be seen at surgery depending on whether the cartilage of the coronoid process is intact or removed. The distance between the tip of the coronoid and the anterior-most point of the RH is similar to the size of shavers used when débriding osteophytes during arthroscopy.

The effect of hemiarthroplasty implant modulus on contact mechanics: an experimental investigation

BACKGROUND

Hemiarthroplasties cause damage to the cartilage that they articulate against, which is a major limitation to their use. This study investigated the use of lower-stiffness materials to determine whether they improve hemiarthroplasty contact mechanics and thus reduce the risk of cartilage damage.

METHODS

Eleven fresh-frozen cadaveric upper extremities were disarticulated and fixed in a custom-built jig that applied a static load of 50 N to the radiocapitellar joint. Flexion angles of 0°, 45°, 90°, and 135° were tested with radial head implants made of cobalt-chrome (CoCr) and ultrahigh-molecular-weight polyethylene (UHMWPE) compared with the native radial head. A Tekscan thin-film sensor was used to measure the contact area and contact pressure between the radius and capitellum.

RESULTS

UHMWPE and CoCr were too stiff in the application of hemiarthroplasty, resulting in lower contact areas and higher contact pressures relative to the native joint. The native contact area was, on average, 42 ± 20 mm² larger than that of UHMWPE (P < .001) and 55 ± 24 mm² larger than that of CoCr (P < .001). UHMWPE had a contact area 13 ± 10 mm² greater than that of CoCr (P = .014).

DISCUSSION AND CONCLUSION

This study shows that even though UHMWPE has a stiffness several times lower than CoCr, the use of this material in hemiarthroplasty led to only a minor improvement in contact mechanics. Neither implant restored contact similar to the native articulation. Investigations into new materials to improve the contact mechanics of hemiarthroplasty should focus on materials with a lower stiffness than UHMWPE.

The role of biceps loading and muscle activation on radial head stability in anterior Monteggia injuries: An in vitro biomechanical study

INTRODUCTION

Little evidence-based information is available to direct the optimal rehabilitation of patients with anterior Monteggia injuries.

PURPOSE OF THE STUDY

The aims of this biomechanical investigation were to (1) quantify the effect of biceps loading and (2) to compare the effect of simulated active and passive elbow flexion on radial head stability in anterior Monteggia injuries.

STUDY DESIGN

In vitro biomechanical study.

METHODS

Six cadaveric arms were mounted in an elbow motion simulator. The effect of biceps loading, simulated active and passive elbow flexion motions was examined with application of 0N, 20N, 40N, 60N, 80N, and 100N of load. Simulated active and passive elbow flexion motions were then performed with the forearm supinated. Radial head translation relative to the capitellum was measured using an optical tracking system. After testing the intact elbows, the proximal ulna was osteotomized and realigned using a custom jig to simulate an anatomical reduction. We then sequentially sectioned the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane to simulate soft tissue injuries commonly associated with anterior Monteggia fractures.

RESULTS

Greater magnitudes of biceps loading significantly increased anterior radial head translation. However, there was no significant difference in radial head translation between simulated active and passive elbow flexion except in the final stage of soft tissue sectioning. There was a significant increase in anterior radial head translation with progressive injury states with both isometric biceps loading and simulated active and passive motion.

CONCLUSIONS

Our results demonstrate that anatomic reduction of the ulna may not be sufficient to restore radial head alignment in anterior Monteggia injuries with a greater magnitude of soft tissue injury. In cases with significant soft tissue injury, the elbow should be immobilized in a flexed and supinated position to allow relaxation of the biceps and avoid movement of the elbow in the early postoperative period.

The Patient-Rated Elbow Evaluation and the American Shoulder and Elbow Surgeons-Elbow form capture aspects of functioning that are important to patients with elbow injuries

STUDY DESIGN

This is a cross-sectional study.

INTRODUCTION

The Patient-Rated Elbow Evaluation (PREE) and the self-report section of the American Shoulder Elbow Surgeons-elbow form (pASES-e) are two important elbow-specific self-report measures used in routine clinical practice.

PURPOSE OF THE STUDY

To use the International Classification of Functioning Disability and Health (ICF) to link aspects of functioning that are reported using the Patient-Specific Functional Scale by a cohort of patients with elbow disorders and compare it to the content of the PREE and the pASES-e.

METHODS

One hundred patients with a variety of elbow disorders (mean age and SD 53.88 (14.51); M: F 48: 52) were recruited from the Roth-McFarlane Hand and Upper Limb Centre. They self-reported important aspects of functioning using the Patient-Specific Functional Scale. These concerns were linked to the ICF using formal linking procedures. These ICF categories were compared to the categories related to the PREE and the pASES-e. Linking was carried out by two independent raters, and agreement was calculated using percentage agreement.

RESULTS

A total of 423 self-reported functional activities were linked to 25 second-level ICF categories from the activity and participation domain. Commonly reported activities were D640 doing housework (52%); D540 dressing (47%); and D475 driving (35%). PREE had better coverage of the patient concerns (71%) than pASES-e (50%). D475-driving (35%) and D440-fine hand use (24%) were the 2 major categories that were not captured by the questionnaires. Agreement between the raters was 90.5%.

DISCUSSION

This study established that the PREE and the pASES-e were able to capture aspects of functioning important to patients and that align with the ICF, with this happening to a greater extent on the PREE than the pASES-e. Because all patients reported concerns from the activity and participation section ('d' categories) of the ICF, this validated that these PROMs measure this conceptual domain.

CONCLUSION

The PREE provided more comprehensive coverage of patients' functional concerns than the pASES-e.

The Unsalvageable Radial Head in Patients Aged 30 Years and Younger

PURPOSE

Concern exists regarding the use of radial head arthroplasty (RHA) in younger patients. This study assessed clinical, functional, and radiographic outcomes of RHA in patients aged 30 years and younger.

METHODS

A retrospective review identified 26 elbows that underwent a smooth stem modular RHA in patients aged 30 years and younger at a median follow-up of 3.3 years clinically and 2.9 years radiographically. The mean age was 24 ± 5 years. Indications were acute trauma in 13 patients and chronic pathologies in the remaining 13, and these 2 groups were evaluated separately. Patients underwent clinical, functional, and radiographic evaluation.

RESULTS

Average arc of motion was 137° ± 16° in the cohort with acute trauma and 120° ± 24° in the cohort with chronic pathologies. Mean Patient-Rated Elbow Evaluation scores were 23 ± 18 (acute) and 31 ± 19 (chronic). Mean Quick Disabilities of the Arm, Shoulder, and Hand scores were 18 ± 15 (acute) and 23 ± 20 (chronic). Average Mayo Elbow Performance Index scores were 90 ± 9 (acute) and 80 ± 13 (chronic). Severe capitellar erosion was present in 1 patient (4%) in the cohort with chronic pathologies. Radiographic stem lucency was seen in all cases with 10 of these (38%) graded as severe. Moderate-to-severe ulnohumeral arthritis developed in 4 patients (15%), 3 of whom were in the chronic reconstruction group. Two patients (8%) required reoperation, 1 for persistent instability and 1 for stiffness, both in the cohort with chronic pathologies.

CONCLUSIONS

For acute trauma and challenging chronic conditions involving the radial head in patients aged 30 years and younger, a smooth stem modular RHA is an option. Although reoperation rates based on this series are low, osteoarthritis is common when used for posttraumatic conditions and severe radiographic stem lucency was seen in greater than one-third of patients. These concerning features warrant close follow-up, and further long-term outcomes are needed.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Coronoid process reconstruction with a distal clavicle autograft: an in silico analysis of fitting accuracy

BACKGROUND

The coronoid process plays a vital role in preserving elbow stability. In cases of acute or chronic deficiency of the coronoid process, reconstruction is warranted to restore stability and to avoid early joint degeneration. The distal clavicle might be a useful osteochondral autograft for coronoid reconstruction with low donor-site morbidity. This study evaluated the fitting accuracy of the distal clavicle as an autograft for coronoid process reconstruction.

METHODS

One hundred upper-extremity computed tomography scans of 85 body donors were available for this study (mean age, 69 ± 17 years; 46 male and 39 female donors; 15 bilateral specimens). Standardized 40% transverse defects of the coronoid process were digitally created; the distal clavicles were digitally harvested and placed onto the defects by a best-fit technique in 2 different orientations using commercially available software: (1) with the superior aspect of the articular surface of the graft oriented toward the coronoid tip and (2) with the inferior aspect of the articular surface of the graft oriented toward the coronoid tip. The fitting accuracy of the grafts to the native coronoid process was evaluated from lateral to medial using custom code.

RESULTS

Regardless of the orientation of the graft, the distal clavicle provided a good fit in the central portion of the coronoid process. In the lateral and medial aspects of the defect, however, the fitting accuracy of the graft declined significantly (P ≤ .044). No significant differences were observed between ipsilateral and contralateral grafts (P ≥ .199). The intrarater reliability was excellent.

CONCLUSION

The results of this study suggest that a distal clavicle autograft may be suitable to replace a transverse defect of the coronoid process; however, it may not fully reconstruct the anteromedial and anterolateral aspects of the coronoid.

Medial elbow exposure: an anatomic comparison of 5 approaches

PURPOSE

Several surgical approaches to the medial elbow are described; however, it remains unclear which exposure provides the optimal view of relevant medial elbow structures. The purpose of this anatomic study was to determine the visible surface area of the coronoid process, distal humerus, and radial head through 5 approaches to the medial elbow.

METHODS

Eight fresh-frozen cadaveric upper extremity specimens were dissected. Five surgical approaches were performed on each specimen. The Smith muscle-splitting approach to the ulnar collateral ligament was performed first (Smith), followed by the Hotchkiss medial "Over the top" approach (Hotchkiss), the extended medial elbow approach (EMEA), the flexor carpi ulnaris splitting approach (FCU-Split), and the Taylor and Scham approach (T&S). Bony visualization was determined using laser surface scanning (Artec Space Spider; Artec 3D). The scans were segmented using commercially available digital software (Geomagic Wrap; 3D Systems Corporation), and the surface area visualized was determined. A descriptive analysis of the joint areas visible using the medial collateral ligament (MCL) as a clinical landmark was performed.

RESULTS

The EMEA visualized the highest proportion of the total elbow joint from the medial side showing 13.9 ± 6.0 cm², or 15% ± 4% of the joint. It also provided the best visualization of the coronoid (3.2 ± 1.7 cm² of surface area, or 26% ± 9%) and distal humerus (9.9 ± 4.3 cm², or 15% ± 4%). The Hotchkiss approach was best at visualizing the radial head (0.8 ± 0.3 cm², or 7% ± 3%). The EMEA, Hotchkiss, and Smith approaches showed primarily the anterior bundle of the MCL, its insertion, and the regions anterior to it, whereas the FCU-Split showed the anterior bundle of the MCL and regions both anterior and posterior to it. The T&S showed primarily the areas posterior to the anterior bundle of the MCL; the anterior regions were not visible. The FCU-Split and the T&S allowed visualization of the posterior bundle of the MCL. The intraclass correlation coefficients (ICCs) for intraobserver reliability were 0.997, 0.992, and 0.974 for the test distal humerus, test coronoid, and test radial head, respectively. The ICCs for interobserver reliability were 0.915 for the test distal humerus, 0.66 for the coronoid, and 0.583 for the radial head.

CONCLUSION

The EMEA provides the most visualization of the coronoid and distal humerus, whereas the Hotchkiss showed the most radial head. However, these approaches mainly visualize structures anterior to the MCL. If exposure of structures posterior to the MCL is required, the FCU-Split and T&S approaches are more appropriate.

Outcomes of nonoperative management of displaced olecranon fractures in medically unwell patients

Background

Surgical treatment of displaced olecranon fractures in the elderly has a high rate of complications, including wound breakdown and fixation failure. The purpose of this study was to assess the clinical, radiographic, and functional outcomes of nonsurgical management of displaced olecranon fractures in low-demand elderly and medically unwell patients.

Methods

A retrospective review of 28 patients with displaced closed olecranon fractures was performed with an average follow-up of 11 months. The mean age at the time of injury was 79 ± 10 years. The average Charlson Comorbidity Index was 6.4 ± 2.6. Treatment modalities were at the discretion of the treating surgeon. A sling alone was used in 3 cases, an extension circumferential cast in 9, or a plaster or thermoplastic splint in 16. The mean period of immobilization was 5 ± 1 weeks. Outcomes included range of motion, ability to perform active overhead extension, as well as radiographic and functional outcomes.

Results

At final follow-up, the mean elbow range of motion for the cohort was from 28° ± 21° extension to 127° ± 15° flexion. Active overhead elbow extension against gravity was noted or documented in 24 (86%) patients. Two patients (7%) were unable to perform active extension. No pain was noted in 18 elbows, severe pain was present in 1 elbow, and the remainder reported mild occasional pain. All olecranon fractures in this cohort were displaced on the initial lateral radiograph. The mean displacement was 11 ± 7 mm. Nonunion at final radiographic outcome was observed in 23 (82%) elbows. Two (7%) patients developed skin complications related to posteriorly placed splints; one of which was severe.

Discussion

This study adds to the growing literature that supports nonoperative management of displaced olecranon fractures in elderly and medically unwell patients with low upper extremity demand. Patients can be counseled that they have a good chance of obtaining overhead extension, with minimal pain. Posteriorly based splints should not be used to minimize skin complications.

Rotational Anatomy of the Radius and Ulna: Surgical Implications

PURPOSE

The rotational anatomy of the forearm bones is not well defined. This study aims to further the understanding of the torsion of the radius and ulna to better guide treatment.

METHODS

Computed tomography images of 98 cadaveric forearms were obtained and 3-dimensional models of the radius and ulna were generated and analyzed. The rotation of the radius was evaluated by comparing the orientation of the distal radius central axis (DRCA) with the volar cortex of the distal radius (DR) and biceps tuberosity (BT). The rotation of the ulna was evaluated by assessing the orientation of the ulnar head with respect to the proximal ulna.

RESULTS

The DR volar cortex pronates from distal to proximal. The BT was 43.8° ± 16.9° supinated from the DRCA (range, 2.7°-86.5°). The mean difference in rotation between contralateral biceps tuberosities was 7.0° ± 7.1°. The volar cortex of the DR was 12.6° ± 5.4° supinated compared with the DRCA. The ulnar head was pronated 8.4° ± 14.9° with respect to the greater sigmoid notch (range, 50.3° pronation-22.0° supination).

CONCLUSIONS

The BT has a variable orientation relative to the DR, but it is generally located anteromedially in a supinated arm or 136° opposite the radial styloid. Understanding the rotational anatomy of the radius and ulna can play an important role in surgical planning and implant design. The rotational anatomy of the radius and ulna varies significantly between individuals, but is similar in contralateral limbs.

CLINICAL RELEVANCE

Distal radius volar cortex rotational anatomy can help guide treatment of DR fractures and malunions as well as assist in positioning of wrist arthroplasty implants, particularly in the presence of bone loss. The side-to-side similarities demonstrated in this study should be helpful in managing patients with segmental bone loss or fracture malunion and those requiring joint reconstruction.

Rehabilitation of Elbow Instability

The elbow is the second most commonly dislocated major joint in adults with estimated incidence of 5 dislocations per 100,000 persons per year. A comprehensive understanding of elbow anatomy and biomechanics is essential to optimize rehabilitation of elbow injuries. This allows for implementation of a systematic therapy program that encourages early mobilization within a safe arc of motion while maintaining joint stability. To optimize outcomes, close communication between surgeon and therapist is necessary to allow for implementation of an individualized rehabilitation program. This article reviews key concepts that enable the clinician to apply an evidence-informed approach when managing elbow instability.

Elbow motion patterns during daily activity

BACKGROUND

This in vivo kinematic study was developed to ascertain (1) elbow posture and motion during daily activities and (2) to compare motions of the dominant and nondominant elbows.

METHODS

Forty-six subjects wore a custom instrumented shirt to continuously measure elbow posture and motion for the waking hours of 1 day. The 3D orientations of each of the forearm and humerus sensors enabled calculation of elbow flexion-extension and pronation-supination angles.

RESULTS

The elbow flexion-extension postures that were most common ranged from 60°-100° for both the dominant and nondominant extremities averaging 44% ± 4% and 35% ± 4% of the day, respectively. When elbow flexion motions were calculated, there were a large number of motions over a wide distribution of flexion angles, with the dominant side exhibiting significantly more motions per hour than the nondominant side.

CONCLUSION

Both flexion-extension and pronation-supination motions occur more commonly in the dominant arm, and the dominant arm is more commonly in pronation. These data provide a baseline for assessing treatment outcomes, ergonomic studies, and elbow arthroplasty wear testing.

Effect of ulnar angulation and soft tissue sectioning on radial head stability in anterior Monteggia injuries: an in vitro biomechanical study

BACKGROUND

Radial head instability continues to be a challenge in the management of anterior Monteggia injuries; however, there is a paucity of literature on the factors that contribute to this instability. The aim of this biomechanical investigation was to examine the effects of ulnar angulation and soft tissue insufficiency on radial head stability in anterior Monteggia injuries.

METHODS

Six cadaveric arms were mounted in an elbow motion simulator. Radial head translation was measured during simulated active elbow flexion with the forearm supinated. After testing the elbows in the intact state, the ulna was osteotomized and tested at 0°, 10°, 20°, and 30° of extension angulation. To examine the effect of soft tissue insufficiency, the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane (IOM) were sequentially sectioned.

RESULTS

There was a significant increase in anterior radial head translation with greater ulnar extension angulation. Sequential soft tissue sectioning also significantly increased anterior radial head translation. There was no increase in radial head translation with isolated sectioning of the anterior radiocapitellar joint capsule. Additional sectioning of the annular ligament and quadrate ligament slightly increased anterior radial head translation but did not reach statistical significance. Subsequent sectioning of the proximal and middle IOM resulted in significant increases in anterior radial head translation.

CONCLUSION

Our study demonstrates that progressive ulnar extension angulation results in an incremental increase in anterior radial head translation in anterior Monteggia injuries. Moreover, increasing magnitudes of soft tissue disruption result in greater anterior radial head instability.

Establishing the psychometric properties of 2 self-reported outcome measures of elbow pain and function: A systematic review

STUDY DESIGN

Systematic review.

INTRODUCTION

The Patient-Rated Elbow Evaluation (PREE) and the self-report section of the American Shoulder and Elbow Surgeons-elbow form (pASES-e) are 2 patient-reported outcome measures (PROMs) commonly used to assess pain and disability arising from elbow disorders.

PURPOSE OF THE STUDY

To systematically review and summarize the quality and content of the evidence that is available on the psychometric properties of the PREE and pASES-e.

METHODS

We systematically searched the online databases PubMed, EMBASE, ProQuest, Scopus, Cumulative Index to Nursing and Allied Health Literature, UptoDate, ProQuest Dissertations & Theses, and Google Scholar. Ninety-one articles were retrieved, and after screening, 9 were included in the final analysis. Data extraction and quality appraisal was performed by 2 independent raters. Descriptive synthesis of the reviewed studies was completed.

RESULTS

Seven of the 9 studies had a quality score of 75% or higher. Agreement between the raters was good (kappa, 0.81). Both the PROMs did not demonstrate any floor and ceiling effects except for the satisfaction subscale of the pASES-e. Factor analysis revealed multidimensionality in the function subscale for both the PROMs. Construct validity was good with correlations above 0.70. Both were highly reliable with interclass correlation coefficient of >0.90. They were also highly responsive with an effect size and standardized response mean above 1. The minimal clinical important difference was not estimated for either measures.

DISCUSSION

This study concluded that strong clinical measurement properties exist for both the PREE and the pASES-e. We identified gaps in the current evidence for both the ASES-e and the PREE. Future studies need to calculate clinically important estimates like MCID, SEM, and others; and provide clear and specific conclusions.

CONCLUSION

The PREE and pASES-e have been established to be valid, reliable, and sensitive to change in both clinical and research settings based on high-quality evidence.

The effect of stem fit on the radiocapitellar contact mechanics of a metallic axisymmetric radial head hemiarthroplasty: is loose fit better than rigidly fixed?

BACKGROUND

Radial head hemiarthroplasty is commonly used to manage comminuted displaced fractures. Regarding implant fixation, current designs vary, with some prostheses aiming to achieve a tight "fixed" fit and others using a smooth stem with an over-reamed "loose" fit. The purpose of this study was to evaluate the effect of radial head hemiarthroplasty stem fit on radiocapitellar contact using a finite element model that simulated both fixed (size-for-size) and loose (1-, 2-, and 3-mm over-reamed) stem fits. It was hypothesized that a loose stem fit would improve radiocapitellar contact mechanics, with an increased contact area and decreased contact stress, by allowing the implant to find its "optimal" position with respect to the capitellum.

METHODS

Finite element models of the elbow were produced to compare the effects of stem fit on radiocapitellar contact of a metallic axisymmetric radial head implant. Radiocapitellar contact mechanics (contact area and maximum contact stress) were computed for 0°, 45°, 90°, and 135° of elbow flexion with the forearm in neutral rotation, pronation, and supination.

RESULTS

The data suggest that the loose smooth stem radial head implant may be functioning like a bipolar implant in optimizing radiocapitellar contact. Over-reaming of 3 mm produced a larger amount of stress concentration on the capitellum, suggesting there may be a limit to how loose a smooth stem implant should be implanted.

CONCLUSIONS

The loose 1 to 2 mm over-reamed stem provided optimal contact mechanics of the metallic axisymmetric radial head implant compared with the fixed stem.

The Effectiveness of a Hinged Elbow Orthosis in Medial Collateral Ligament Injuries: An In Vitro Biomechanical Study

BACKGROUND

Medial collateral ligament (MCL) injuries are common after elbow trauma and in overhead throwing athletes. A hinged elbow orthosis (HEO) is often used to protect the elbow from valgus stress early after injury and during early return to play. However, there is minimal evidence regarding the efficacy of these orthoses in controlling instability and their influence on long-term clinical outcomes.

PURPOSE

(1) To quantify the effect of an HEO on elbow stability after simulated MCL injury. (2) To determine whether arm position, forearm rotation, and muscle activation influence the effectiveness of an HEO.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven cadaveric upper extremity specimens were tested in a custom simulator that enabled elbow motion via computer-controlled actuators and motors attached to relevant tendons. Specimens were examined in 2 arm positions (dependent, valgus) and 2 forearm positions (pronation, supination) during passive and simulated active elbow flexion while unbraced and then while braced with an HEO. Testing was performed in intact elbows and repeated after simulated MCL injury. An electromagnetic tracking device measured valgus angulation as an indicator of elbow stability.

RESULTS

When the arm was dependent, the HEO increased valgus angle with the forearm in pronation (+1.0°± 0.2°, P = .003) and supination (+1.5°± 0.0°, P = .006) during active motion. It had no significant effect on elbow stability during passive motion. In the valgus position, the HEO had no effect on elbow stability during passive or active motion in pronation and supination. With the arm in the valgus position with the HEO, muscle activation reduced instability during pronation (-10.3°± 2.5°, P = .006) but not supination (P = .61).

CONCLUSION

In this in vitro study, this HEO did not enhance mechanical stability when the arm was in the valgus and dependent positions after MCL injury.

CLINICAL RELEVANCE

After MCL injury, an HEO likely does not provide mechanical elbow stability during rehabilitative exercises or when the elbow is subjected to valgus stress such as occurs during throwing.

The Capitate-to-Axis-of-Radius Distance (CARD): A New Radiographic Measurement for Wrist and Carpal Alignment in the Sagittal Plane

PURPOSE

To determine the reliability of a new radiographic index evaluating sagittal radiocarpal alignment, the capitate-to-axis-of-radius distance (CARD). A secondary purpose was to validate this index by comparing values between normal wrists and those with distal radial fractures (DRFs) and rheumatoid arthritis (RA).

METHODS

The CARD is defined as the perpendicular distance from the center of the capitate head to the axis of the radius. Inter- and intraobserver reliability was tested. Cronbach alpha was calculated, and 2 methods of measurement were compared. The superior one (volar border of radial shaft) was used in the second part of the study. The normal CARD was then compared with unilateral DRFs with dorsal displacement DRF (n = 25) and RA (n = 25). Correlations between the CARD and other radiographic parameters (dorsal angulation, radial inclination, and ulnar variance) were calculated as well as between the CARD and the severity of disease or fracture displacement (mild/moderate/severe).

RESULTS

The CARD showed excellent intra- and interobserver reliability. The volar radius measurement method was superior to the midaxis method and was, therefore, used for the second portion of the study. The mean CARD for normal, fractured, and RA wrists was significantly different (2.2 ± 2.5 mm, 15.7 ± 6.5 mm and 0.2 ± 4.4 mm, respectively). There was a strong side-to-side correlation in normal wrists (r = 0.77) and a significant correlation between the CARD (mm) and the severity of deformity (RA, r = -0.7; DRF, r = 0.8).

CONCLUSION

The CARD is a reproducible, easy-to-use measurement of sagittal carpal alignment with a strong side-to-side correlation. The CARD increases with dorsal angulation of the distal radius and decreases as severity of deformity with RA increases.

CLINICAL RELEVANCE

The correlation of the CARD with severity of deformity in DRFs and RA makes it a useful method of assessing deformities in the sagittal plane. The normal wrist can be used as a comparison when evaluating the CARD in the setting of unilateral wrist disease.

Computed Tomography Analysis of the Radial Notch of the Ulna

PURPOSE

The anatomy of the radial head and capitellum has been extensively studied; however, the anatomy of the radial notch of the ulna (RNU) has received little attention. This imaging-based anatomic study characterizes the morphology of the RNU.

METHODS

Ninety-eight cadaveric arms (57 male, 72 ± 14 y) were imaged with computed tomography, and 3-dimensional reconstructions of the proximal ulna were constructed. The anteroposterior and proximal-distal dimensions of the RNU as well as the radius of curvature at standardized levels were measured in 2-mm increments. The orientation of the RNU was also determined.

RESULTS

The proximal-distal and anteroposterior dimensions of the RNU were 12 ± 2 mm (range, 7-16 mm) and 18 ± 3 mm (range, 12-24 mm), respectively. The average radius of curvature of the RNU was 15 ± 0 mm (range, 15-16 mm). The radius of curvature did not change significantly when comparing the proximal and distal aspect of the RNU. The RNU was rotated 33° ± 2° (range, 31° to 38°) externally relative to the transverse plane of the ulna. The average depth of the RNU at its deepest point was 2.2 ± 0.4 mm (range, 1.5-2.7 mm). The depth decreased from proximal to distal, being most shallow distally. The depth changed by an increase of the radius of curvature, as well as by rotation in the frontal plane.

CONCLUSIONS

The RNU anatomy was variable, generally extending laterally from proximal to distal. This suggests that a radial head implant should taper from proximal to distal to optimize contact at the RNU.

CLINICAL RELEVANCE

The present study investigates the detailed anatomy of the radial notch of the ulna using computed tomography scans. The data might help improve the design of prosthetic components.

An In Vitro Study to Determine the Effect of Ulnar Shortening on Distal Forearm Loading During Wrist and Forearm Motion: Implications in the Treatment of Ulnocarpal Impaction

PURPOSE

To evaluate the effect of ulnar shortening on distal forearm loading following simulated dynamic motion.

METHODS

Ulnar shortening was simulated using a custom-built adjustable implant to simulate up to 4 mm of ulnar shortening (-4 mm) in 9 cadaveric extremities. Load cells were placed in the distal ulna and radius to quantify axial loading. Using a wrist and forearm motion simulator, absolute and percentage loads were measured during dynamic flexion, ulnar deviation (UD), flexion dart throw (DT), and pronation.

RESULTS

There was a significant decrease in absolute and percentage distal ulnar loads at each interval of ulnar shortening during flexion, UD, DT, and pronation. The distal ulna bore no compressive loads, and in fact, tensile loads were measured in the ulna at 2 mm of ulnar shortening during DT and pronation, at 3 mm during flexion, and at 4 mm during UD.

CONCLUSIONS

A progressive decrease in distal ulnar loads with generation of tensile loads was observed with sequential ulnar shortening.

CLINICAL RELEVANCE

Ulnar shortening greater than 2 mm can result in tensile loading in the distal ulna. When managing ulnar impaction syndrome, excessive shortening may not be required to provide relief of symptoms.

Effect of Radial Lengthening on Distal Forearm Loading Following Simulated In Vitro Radial Shortening During Simulated Dynamic Wrist Motion

PURPOSE

To evaluate the effect of radial length change on distal forearm loading during simulated dynamic wrist motion.

METHODS

A custom-built adjustable radial implant was used to simulate up to 4 mm of distal radius shortening (-4 mm) and 3 mm of lengthening (+3 mm). Load cells were placed in the distal radius and ulna in cadavers to measure their respective axial loads. The specimens were mounted on a wrist motion simulator that produced active wrist motion via tendon actuation. To simulate radial lengthening osteotomy following radial shortening from malunion, the radius was sequentially lengthened by 1-mm intervals from -4 mm to +3 mm. Radial and ulnar loads were measured during simulated wrist flexion, ulnar deviation (UD), and flexion dart throw (DT) at each interval of radial lengthening up to +3 mm.

RESULTS

During wrist flexion and UD, for each millimeter of radial lengthening from -4 mm to the native length, there was a significant increase in distal radial loads. No significant change in radial load was observed beyond the native length during flexion and UD. There was no change in distal radial loads during DT for each interval of radial lengthening from -4 mm to +3 mm. A sequential decrease in ulnar loads was observed as the radius was lengthened from -4 mm to +3 mm for all wrist motions evaluated.

CONCLUSIONS

Radial lengthening beyond the native length was not detrimental to radial loading and further reduced distal ulnar loading; achieving at least native ulnar variance seems to be appropriate to restore normal biomechanical loading based on this in vitro study.

CLINICAL RELEVANCE

Lengthening of the radius beyond native variance in the setting of ulnar impaction syndrome, distal radius malunion, or distal radioulnar instability may not result in excessive loading of the distal radius and further reduces loading on the distal ulna. Surgeons should obtain contralateral wrist x-rays to serve as a template when performing distal radius osteotomies.

The effect of torsional moments on the posterolateral rotatory stability of a lateral ligament deficient elbow: An in vitro biomechanical investigation

BACKGROUND

Clinical tests for posterolateral rotatory instability of the elbow apply external torsional moments to the forearm; however, biomechanical studies of lateral collateral ligament injuries and their surgical repair, reconstruction and rehabilitation have primarily relied on varus gravity loading to quantify instability. The aim of this investigation was to determine the effect of torsional moments on the posterolateral rotatory instability of the lateral ligament deficient elbow.

METHODS

Six cadaveric arms were tested in an elbow motion simulator with the arm in the varus position. A threaded outrigger was inserted on the dorsal aspect of the proximal ulna to suspend 400 g, 600 g, and 800 g of weight to allow torsional moments of 0.12, 0.18, and 0.23 Nm respectively on the ulna. An injured model was created by sectioning of the common extensor origin, and the lateral collateral ligament.

FINDINGS

During simulated active flexion with the arm in varus, the injured model resulted in a significant increase in external rotation of the ulnohumeral articulation with the forearm both pronated and supinated (pronation: P = .021; supination: P = .015). The application of torsional moments to the lateral ligament deficient elbow resulted in a significant increase in the posterolateral rotatory instability of the elbow.

INTERPRETATION

This investigation demonstrates that the application of even small amounts of external torsional moments on the forearm with the arm in the varus position increases the rotational instability of the lateral ligament deficient elbow. During clinical examination for posterolateral rotatory instability and biomechanical studies of lateral ligament injury, the application of external torsion to the forearm should be considered to detect subtle instability.

LEVEL OF EVIDENCE

Basic Science Study.

Management of chronic distal biceps tendon ruptures: primary repair vs. semitendinosus autograft reconstruction

BACKGROUND

Delayed presentation of distal biceps tendon ruptures can make primary repair difficult, in which case reconstruction using a tendon graft is an option. The aim of this study was to compare outcomes and complications between delayed distal biceps tendon ruptures managed with repair vs. semitendinosus autograft reconstruction.

METHODS

Nineteen delayed distal biceps tendon rupture cases treated with a tendon reconstruction were compared with 16 delayed primary repair cases (>21 days). The reconstructions were performed using a semitendinosus autograft looped through a transosseous tunnel in the bicipital tuberosity and secured with a Pulvertaft weave to the remnant distal biceps tendon. The patient groups were reviewed and completed functional outcomes testing including range of motion, isometric elbow flexion and supination strength, Disabilities of the Arm, Shoulder, and Hand, Patient-Rated Elbow Evaluation, Single Assessment Numeric Evaluation, and Mayo Elbow Performance Index.

RESULTS

Mean patient age (49 ± 9 vs. 46 ± 8 years, P = .65) and follow-up (47 ± 25 vs. 45 ± 27 months, P = .45) were similar between delayed primary repair and reconstruction groups. Range of motion (P = .62), supination strength (P = .26), elbow flexion strength (P = .93), Disabilities of the Arm, Shoulder, and Hand (P = .08), and Single Assessment Numeric Evaluation (P = .22) were not significantly different between groups. The Patient-Rated Elbow Evaluation (P = .02) and Mayo Elbow Performance Index (P = .04), however, were better in the delayed repair group compared with the reconstruction group. Complications were similar between groups (P = .87).

CONCLUSION

Delayed reconstruction of irreparable distal biceps tendon ruptures with semitendinosus autograft produces similar strength, range of motion, and complication rates but slightly worse functional outcome scores compared with delayed primary repair. This suggests that when possible direct repair is preferred, however, if not possible, reconstruction with an autologous tendon graft results in predictably good outcomes.

Role of the anconeus in the stability of a lateral ligament and common extensor origin-deficient elbow: an in vitro biomechanical study

BACKGROUND

The role of the anconeus in elbow stability has been a long-standing debate. Anatomic and electromyographic studies have suggested a potential role as a stabilizer. However, to our knowledge, no clinical or biomechanical studies have investigated its role in improving the stability of a combined lateral collateral ligament and common extensor origin (LCL + CEO)-deficient elbow.

METHODS

Seven cadaveric upper extremities were mounted in an elbow motion simulator in the varus position. An injured model was created by sectioning of the CEO and the LCL. The anconeus tendon and its aponeurosis were sutured in a Krackow fashion and tensioned to 10 N and 20 N using a transosseous tunnel. Varus-valgus angles and ulnohumeral rotations were recorded using an electromagnetic tracking system during simulated active elbow flexion with the forearm pronated and supinated.

RESULTS

During active motion, the injured model resulted in a significant increase in varus angulation (P = .0001 for pronation; P = .001 for supination) and external rotation (P = .001 for pronation; P = .003 for supination) of the ulnohumeral articulation compared with the intact state. Tensioning of the anconeus significantly decreased the varus angulation (P = .006 for 10 N pronation; P = .0001 for 20 N pronation; P = .0001 for 10 N supination; P = .0001 for 20 N supination) and external rotation angle (P = .008 for 10 N pronation; P = .0001 for 20 N pronation; P = .0001 for 10 N supination; P = .0001 for 20 N supination) of the injured elbow.

CONCLUSIONS

In the highly unstable varus elbow orientation, anconeus tensioning restores the in vitro stability of a combined LCL + CEO-deficient elbow during simulated active motion with the forearm in both pronation and supination. These results may have several clinical implications in managing symptomatic lateral elbow instability.

The shape match of the olecranon tip for reconstruction of the coronoid process: influence of side and osteotomy angle

BACKGROUND

The integrity of the coronoid process is critical to maintaining elbow stability. Unreconstructible fractures and chronic coronoid deficiency are challenging clinical problems with no clear solution. The purposes of this study were to investigate the shape match of the ipsilateral and contralateral olecranon tips as graft options and to determine the influence of the osteotomy angle on fitment.

METHODS

Nineteen paired cadaveric elbow joints were investigated by 3-dimensional digital analysis of computed tomography DICOM (Digital Imaging and Communications in Medicine) data. After construction of an ulnar coordinate system, the ipsilateral and contralateral olecranon tips were digitally harvested at 10°, 20°, 30°, 40°, 50°, and 60° osteotomy angles. In an overlay analysis, we compared the shape match of the ipsilateral and contralateral grafts and the different angles.

RESULTS

The ipsilateral grafts showed an average mismatch of 1.8 mm (standard deviation, 1.38 mm), whereas the contralateral grafts had a significantly lower (P < .001) mean mismatch of 1.3 mm (standard deviation, 0.95 mm). The 50° osteotomy plane showed the best shape match in comparison with the native coronoid-in both the ipsilateral and contralateral grafts. Evaluation of the intraclass correlation coefficient was calculated at r = 0.944, showing high repeatability of the measurements.

CONCLUSIONS

The contralateral olecranon tip graft showed significantly better shape matching to the native coronoid than the ipsilateral olecranon graft. Specifically, the contralateral graft more closely matched the biomechanically critical anteromedial coronoid facet. Finally, both the contralateral and ipsilateral olecranon grafts had better shape matching with the native coronoid when osteotomy was performed at higher angles, specifically 50°.

The Effect of Dorsal Angulation on Distal Radioulnar Joint Arthrokinematics Measured Using Intercartilage Distance

Background  The effects of dorsal angulation deformity on in vitro distal radioulnar joint (DRUJ) contact patterns are not well understood. Purpose  The purpose of this study was to utilize intercartilage distance to examine the effects of forearm rotation angle, distal radius deformity, and triangular fibrocartilage complex (TFCC) sectioning on DRUJ contact area and centroid position. Methods  An adjustable implant permitted the creation of simulated intact state and dorsal angulation deformities of 10, 20, and 30 degrees. Three-dimensional cartilage models of the distal radius and ulna were created using computed tomography data. Using optically tracked motion data, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. Results  DRUJ contact area was highest between 10 and 30 degrees of supination. TFCC sectioning caused a significant decrease in contact area with a mean reduction of 11 ± 7 mm ² between the TFCC intact and sectioned conditions across all variables. The position of the contact centroid moved volarly and proximally with supination for all variables. Deformity had a significant effect on the location of the contact centroid along the volar-dorsal plane. Conclusion  Contact area in the DRUJ was maximal between 10 and 30 degrees of supination during the conditions tested. There was a significant effect of simulated TFCC rupture on contact area in the DRUJ, with a mean contact reduction of 11 ± 7 mm ² after sectioning. Increasing dorsal angulation caused the contact centroid to move progressively more volar in the sigmoid notch.

Arthroscopic debridement for primary elbow osteoarthritis with and without capsulectomy: a comparative cohort study

BACKGROUND

Arthroscopic elbow debridement for primary osteoarthritis may be performed with or without a joint capsulectomy. The purpose of this comparative cohort study was to compare range of motion (ROM) and early complications between patients with and without anterior capsulectomy.

METHODS

In total, 110 patients with primary osteoarthritis of the elbow who underwent an arthroscopic debridement for primary osteoarthritis were reviewed with a minimum of 3 months postoperative follow-up. The first group consisted of 51 patients who had a concomitant capsulectomy and the second group consisted of 59 patients who either had a capsulotomy or did not have the capsule addressed.

RESULTS

There was significantly greater pre-operative stiffness in the group who had an anterior capsulectomy versus those who did not. A greater improvement in arc of ROM occurred in patients who had a concomitant capsulectomy compared to patients without (24° versus 12°) (p < 0.003); however, there were no significant differences in final ROM between groups. There were no statistically significant differences in the incidence of complications between the groups (16% capsulectomy versus 18% no capsulectomy).

CONCLUSIONS

Elbow arthroscopy and debridement for primary elbow osteoarthritis yields satisfactory motion at short-term follow-up with or without a capsulectomy. The incidence of early complications was low at this tertiary referral centre, with no significant differences between groups.

In Vitro Kinematic Assessment of a Hinged Elbow Orthosis Following Lateral Collateral Ligament Injury

PURPOSE

Elbow lateral collateral ligament injuries (LCLI) are often managed with protected mobilization using a hinged elbow orthosis (HEO). The objective of this investigation was to determine the effectiveness of an HEO in stabilizing the elbow following LCLI.

METHODS

Seven fresh-frozen cadaveric upper extremity specimens were studied using a custom simulator that enabled elbow motion via computer-controlled actuators and servomotors attached to relevant tendons. Specimens were examined in 4 arm positions (dependent, overhead, horizontal, and varus) and 2 forearm positions (pronation and supination) during both passive and simulated active elbow extension. Specimens were examined before and after simulated LCLI, and then with the addition of an HEO. The lateral collateral ligament, common extensor origin, and lateral elbow capsule were sectioned in the injury model. An electromagnetic tracking system measured ulnohumeral kinematics.

RESULTS

The orthosis did not change elbow stability in any arm position during active motion. Muscle activation and forearm pronation enhanced stability in the dependent, horizontal, and varus positions while the HEO was applied.

CONCLUSIONS

This HEO does not improve the in vitro stability of the elbow following simulated LCLI.

CLINICAL RELEVANCE

An HEO may be safe to use during active motion, but when a patient is not activating the muscles normally (ie, owing to fatigue or cognitive impairment) and the arm is in positions in which the weight of the orthosis might increase joint distraction, an HEO may be harmful. If an HEO is used, the forearm should be braced in pronation following LCLI.

Design of Anatomical Population-Based and Patient-Specific Radial Head Implants

PURPOSE

The objective of this study was to characterize the morphology of the radial head and design population-based anatomical and patient-specific radial head implants.

METHODS

Computed tomography (CT) images of 50 normal cadaveric upper extremities (34 male, 16 female) were obtained using a 64-slice CT scanner. Surface models were ellipse-fitted and characterized. Using an intersurface distance mapping approach, the surface geometry of the population-based anatomical design (PB-An), 3 distinct patient-specific designs, and an existing axisymmetrical implant (Com-Axi) were compared with the native radial head and the overall surface mismatch was measured.

RESULTS

Morphological analysis indicated that the diameters of the outer and rim ellipses were correlated. The mean mismatch for the existing commercially available axisymmetrical implants was 0.5 ± 0.1 mm.The PB-An implants showed significantly reduced surface mismatch (0.4 ± 0.2 mm). The PS-An implant using 82 parameters in its design (0.1 ± 0.0 mm), had the lowest mean surface mismatch of any of the implants investigated.

CONCLUSIONS

The mean surface mismatch of radial head implants may be reduced using reverse engineering techniques to determine the required parameters for both population-based and patient-specific implant designs. Whether there is a significant clinical advantage of a more anatomically shaped radial head implant requires additional study. More anatomical implant shapes rely on a surgical technique to accurately position these implants during surgery. It is unclear if this can be achieved clinically using conventional techniques or whether computer-assisted surgery will be required to realize the potential advantages of a more anatomical implant.

CLINICAL RELEVANCE

This study characterized the morphology of the radial head with implications for population-based anatomical implants and patient-specific implants. The overall design of each implant was quantitatively compared with the native radial head. This study has implications for the design of patient-specific/anatomical implants and compares their use with commercially available generic implants.

Delayed repair of distal biceps tendon ruptures is successful: a case-control study

BACKGROUND

The literature has shown an increased complication rate with a delay to surgical repair of acute distal biceps tendon ruptures; however, little has been documented regarding the outcome of delayed repairs. This case-control study compared a study cohort of delayed (>21 days) distal biceps tendon repairs with a control cohort repaired acutely (<21 days).

METHODS

Sixteen delayed repair cases were reviewed and matched with acute controls (1:3) based on repair technique, age, and workers' compensation status. The delayed cohort was reviewed and completed isometric strength testing and the Disabilities of the Arm, Shoulder and Hand questionnaire; Patient-Rated Elbow Evaluation; and American Shoulder and Elbow Surgeons elbow questionnaire.

RESULTS

The time to surgery averaged 37 ± 12 days in the delayed cohort versus 10 ± 6 days in the acute cohort. Complications occurred in 63% of patients in the delayed cohort versus 29% in the acute cohort (P = .04); however, 90% of the delayed cohort's complications consisted of transient paresthesias. Follow-up scores on the Patient-Rated Elbow Evaluation, Disabilities of the Arm, Shoulder and Hand questionnaire, and American Shoulder and Elbow Surgeons elbow questionnaire were not statistically different between cohorts (P > .37, P > .22, and P > .46, respectively).

CONCLUSIONS

Despite a high rate of initial complications, patients treated with distal biceps tendon repair after a delay (>21 days) can expect similar functional outcomes to those treated acutely.

Effect of Radial Head Implant Shape on Radiocapitellar Joint Congruency

PURPOSE

Radial head arthroplasty is indicated in displaced fractures in which comminution precludes successful internal fixation. Many types of radial head implants have been developed varying in material, methods of fixation, and degrees of modularity and geometry. The purpose of this study was to investigate the effect of radial head implant shape on radiocapitellar joint congruency.

METHODS

Joint congruency was quantified in 7 cadaveric specimens employing a registration and inter-surface distance algorithm and 3-dimensional models obtained using computed tomography. Forearm rotation was simulated after computer-guided implantation of an axisymmetric radial head, a population-based quasi-anatomic radial head implant, and a reverse-engineered anatomic radial head implant. Inter-surface distances were measured to investigate the relative position of the radial head implant and displayed on 3-dimensional color-contour maps. Surface area was measured for inter-surface distances (1.5 mm) and compared for each radial head geometry.

RESULTS

There were no statistical differences in the contact surface area between radial head implants during active or passive forearm rotation. The joint was more congruent (larger contact surface area) during active forearm rotation compared with passive forearm rotation.

CONCLUSIONS

This study investigated the effect of implant geometry on the radiocapitellar joint contact mechanics by examining a commercially available radial head system (axisymmetric), a quasi-anatomic design, and an anatomic reverse-engineered radial head implant. We found no statistical differences in radiocapitellar joint contact mechanics as measured by 3-dimensional joint congruency in cadaveric specimens undergoing continuous simulated forearm rotation.

CLINICAL RELEVANCE

The importance of choosing an implant that matches the general size of the native radial head is recognized, but the degree to which it is necessary to create an implant that replicates the native anatomy to restore elbow stability and prevent cartilage degenerative changes remains unclear. This study concluded that the geometry of the implant did not have a statistically significant effect on joint contact mechanics; therefore, future work is needed to examine additional factors related to implant design, such as material choice and implant positioning to investigate their influence on joint contact mechanics.

Optimizing the rehabilitation of elbow lateral collateral ligament injuries: a biomechanical study

BACKGROUND

Elbow lateral collateral ligament (LCL) injury may arise after trauma or lateral surgical approaches. The optimal method of rehabilitating the LCL-insufficient elbow is unclear. Therapists often prescribe active motion exercises with the forearm pronated. Recently, overhead exercises have become popular as they may enable gravity to compress the elbow joint, improving stability, although this has not been proved biomechanically. This investigation aimed to quantify the effects of several variables used in LCL injury rehabilitation on elbow stability.

METHODS

Seven cadaveric specimens were tested in a custom elbow motion simulator in 3 arm positions (overhead, dependent, and varus) and 2 forearm positions (pronation and supination) during passive and simulated active elbow extension. Three injury patterns were studied (intact, LCL injury, and LCL with common extensor origin injury). An electromagnetic tracking device measured ulnohumeral kinematics.

RESULTS

Following combined LCL and common extensor origin injury, overhead positioning enhanced elbow stability relative to the other arm positions (P < .01 in pronation; P = .04 in supination). Active motion stabilized the LCL-deficient elbow in the dependent (P = .02) and varus (P < .01) positions. Pronation improved stability in the overhead (P = .05), dependent (P = .06), and varus (P < .01) positions.

CONCLUSIONS

Rehabilitation with the arm overhead improves elbow stability after LCL injury. Initiating earlier range of motion in this "safe position" might decrease elbow stiffness and allow optimal ligament healing. If exercises are done in the dependent position, active motion with forearm pronation should be encouraged. Varus arm positioning should be avoided.

Treatment of Radial Head Fractures with a Modular Metallic Radial Head Replacement

Introduction

Radial head arthroplasty with a smooth-stemmed metallic modular implant is a reliable treatment option for patients with acute unreconstructible radial head fractures, and good clinical outcomes may be expected beyond 5 years of follow-up (Video 1).

Indications & Contraindications

Step 1 Preoperative Planning

Obtain a careful history and perform a physical examination along with appropriate imaging to facilitate appropriate treatment decisions.

Step 2 Operating Room Setup and Patient Positioning

Perform proper operating room setup and patient positioning, as they are required to gain access to all affected structures around the elbow in a safe and efficient manner.

Step 3 Approach

Make a midline posterior skin incision with development of a full-thickness lateral fasciocutaneous flap or use a direct lateral incision; the deep interval is determined on the basis of the integrity of the LCL.

Step 4 Radial Head Excision

Remove and preserve all fragments of the radial head for implant sizing.

Step 5 Implant Sizing

Implant a prosthesis that closely replicates the dimensions of the native radial head, which is the primary goal of the procedure.

Step 6 Stem Broaching

Sequentially broach the canal until good cortical contact is achieved and undersize the definitive stem by 1 mm to allow implant movement within the canal and appropriate articulation with the capitellum.

Step 7 Insertion of Trial Components and Final Radial Head Implant

With the selected trial in place, assess the radial head diameter, height, and articular congruency.

Step 8 Closure and Repair of the LCL

Ensure proper repair of the LCL as it is essential to maintaining or restoring elbow stability.

Step 9 Postoperative Protocol

Postoperative rehabilitation depends on the status of the collateral ligaments.

Results

In a review of the cases of 55 patients at a mean follow-up of 8 years after radial head arthroplasty with a smooth-stemmed modular metallic prosthesis, Marsh et al.⁹.

Pitfalls & Challenges

Kinematics of Ulnar Head Arthroplasty

This in vitro study evaluated the performance of an ulnar head replacement. A joint simulator was employed that produced active forearm rotation in cadaveric specimens, with motion measured using an electromagnetic tracking system. The kinematics of the intact forearm were compared with a partial ulnar head replacement and a full replacement (with and without soft-tissue reconstruction) and a full excision of the ulnar head. There were no differences between intact kinematics and those following prosthetic reconstruction. However, ulnar head excision produced distal radioulnar joint instability in the form of radioulnar convergence and increased anteroposterior translations.

Osseous Anatomy of the Distal Radioulnar Joint: An Assessment Using 3-Dimensional Modeling and Clinical Implications

PURPOSE

Using a novel technique, we assess and describe the distal radioulnar joint (DRUJ) anatomy. The purpose of this study was to provide the anatomic dimensions of the DRUJ and to evaluate contralateral symmetry.

METHODS

Computed tomography images of 100 cadaveric forearms were obtained. Three-dimensional models of the radius and ulna were generated and evaluated using 3-dimensional modeling software. Measurements of the radius of curvature of the sigmoid notch (SN) and ulnar head (UH), as well as the length of the SN and volar and dorsal lips were performed in the axial and coronal sequences. In addition, mid-coronal angular measurements were made of the SN and UH to quantify the obliquity of the DRUJ. All coronal measurements were performed with the forearm set to neutral rotation.

RESULTS

The average ulnar variance was -0.9 ± 1.8 mm. The radius of curvature of the UH (8.2 ± 1.3 mm) was markedly smaller than that of the SN (18.2 ± 8.5 mm). The length of the SN in coronal sequences increased from volar to dorsal by 65%. The mid-coronal angle (DRUJ obliquity) of the SN and UH measured 6.0 ± 9.9° and 18.0 ± 9.9°, respectively. A direct inverse correlation was demonstrated in the obliquity of the DRUJ and ulnar variance. All anatomic measurements were similar when comparing bilateral specimens.

CONCLUSIONS

The SN length tends to increase in size from volar to dorsal. Bilateral specimens from the same individual demonstrate similarities and can be cautiously used for comparison.

CLINICAL RELEVANCE

The relationships and measurements demonstrated in this study can be a guide when considering reconstructive procedures or dealing with complex fractures involving the DRUJ.

Selected anteromedial coronoid fractures can be treated nonoperatively

BACKGROUND

Surgical fixation is currently recommended for unstable anteromedial coronoid fractures, but the role of nonoperative management is not well defined. Our purpose was to report the functional and radiographic outcomes of select patients managed nonoperatively.

METHODS

Between 2006 and 2012, 10 patients with anteromedial coronoid fractures underwent nonoperative treatment. Outcomes assessed included elbow range of motion (ROM), stability, strength, radiographs, and 3 functional questionnaires, including the Patient-Rated Elbow Evaluation, Disabilities of Arm, Shoulder and Hand, and Mayo Elbow Performance Index.

RESULTS

There were 9 anteromedial subtype 2 coronoid fractures and 1 subtype 3. Mean fragment size was 5 mm, with a mean displacement of 3 mm for the subtype 2 fractures. The subtype 3 fracture was 9 mm in size with 1 mm of maximal gap displacement. At a mean follow-up of 50 months (range, 12-83 months), the average ROM of the affected elbow was 137° ± 8° of flexion, 2° ± 5° of extension, 88° ± 5° of pronation, and 86° ± 10° of supination. The mean Patient-Rated Elbow Evaluation score was 9 ± 13, Mayo Elbow Performance Index score was 94 ± 8, and the Disabilities of Arm, Shoulder and Hand score was 7 ± 9. All patients had bony union without radiographic arthrosis. There were no cases of recurrent instability or delayed surgical intervention.

CONCLUSIONS

Current indications for nonoperative management, based on the results of this study, include fractures that are small, minimally displaced, and most importantly, demonstrate no evidence of elbow subluxation. The elbow joint must be congruent and demonstrate a stable ROM to a minimum of 30° of extension. For selected anteromedial coronoid fractures, nonoperative management is an option that can lead to good clinical and radiographic outcomes.

The Effect of Radial Head Hemiarthroplasty Geometry on Proximal Radioulnar Joint Contact Mechanics

PURPOSE

To compare the joint contact area and peak contact stress of different radial head (RH) hemiarthroplasty articular profiles for the proximal radioulnar joint (PRUJ) to the native radial head with the hypothesis that the side radius and side angle closest to the native mating ulnar articular profile would provide the best contact mechanics.

METHODS

Finite element models generated from the computed tomography geometry of 14 native elbows (73 ± 17.5 years) were subjected to 12 different RH profiles having varying side radii (flat [r = ∞ mm], 16.25, 8.12, and 4.50 mm) and side angles (0°, 5°, and 10°) under a constant compressive 20-N medial load. Contact areas and peak contact stresses were computed and compared with the native joint.

RESULTS

On average, RH implants significantly reduced PRUJ contact area by 55% ± 16% and increased peak contact stress by 337% ± 241% compared with the native RH. The prosthesis side radius had significant effects on both contact area and stress, but side angle did not. The 16.25-mm radii produced the largest contact areas, and the 4.50-mm radius model generated the smallest contact areas. As the side radius was decreased, peak contact stress was reduced as the contact migrated toward the center of the native ulnar articulation, although the 8.12-mm radius achieved the lowest peak contact stress.

CONCLUSIONS

Whereas RH hemiarthroplasty side radius can affect both contact area and peak contact stress, the magnitude of the effect on contact area is relatively small compared with that of the peak contact stress. Furthermore, although a flat RH side profile with a side angle of 5° more closely matched the side profile of the native ulnas used in the present study, the optimal profile was found to be a smaller radius of 8.12 mm.

CLINICAL RELEVANCE

Optimizing PRUJ contact mechanics after metallic RH hemiarthroplasty may contribute to better clinical outcomes by reducing the potential for native cartilage degeneration.

Radial Head Fractures Treated with Modular Metallic Radial Head Replacement: Outcomes at a Mean Follow-up of Eight Years

BACKGROUND

Radial head arthroplasty is commonly used to treat acute unreconstructible radial head fractures. The purpose of this study was to report on the clinical and radiographic outcomes at a minimum follow-up of five years after radial head arthroplasty with a modular metallic implant for the treatment of acute radial head fractures.

METHODS

The cases of fifty-five patients with unreconstructible radial head fractures treated acutely with a smooth-stemmed modular metallic radial head implant were retrospectively reviewed. A wide variety of injuries, which ranged from isolated radial head fractures to so-called terrible triad injuries, were included. All patients returned for an interview, physical examination, and radiographic evaluation at a mean of eight years (range, five to fourteen years) postoperatively. Elbow and forearm motion, elbow strength, and grip strength were measured. Radiographs were evaluated, and validated patient-rated outcome questionnaires were completed. A longitudinal subgroup analysis was performed for thirty-three patients who were previously evaluated at two years postoperatively.

RESULTS

At a mean of 8.2 ± 2.9 years, the mean arc of flexion (and standard deviation) of the affected elbow was 11° ± 14° to 137° ± 15°. Elbow strength and motion were significantly diminished compared with the unaffected elbow (p < 0.05). The mean Mayo Elbow Performance Index (MEPI) was 91 ± 13 points. Twenty-five patients (45%) had stem lucencies; twenty-one (38%), ulnohumeral arthritis; and twenty (36%), heterotopic ossification, including one with radioulnar synostosis. Two patients underwent secondary elbow surgery, but no patient required implant removal or revision. In the subgroup evaluated longitudinally, there was a significant improvement in MEPI scores from the two-year to the eight-year follow-up (p = 0.012), with no loss of motion or strength (p > 0.05).

CONCLUSIONS

The mid-term outcomes of radial head arthroplasty with a smooth-stemmed modular metallic prosthesis are comparable with previously reported short-term outcomes, with no evidence of functional deterioration. Radial head arthroplasty with a smooth-stemmed metallic modular implant is a good treatment option for patients with acute unreconstructible radial head fractures, and sustained clinical outcomes may be expected beyond five years of follow-up.

LEVEL OF EVIDENCE

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

The relationship between the Patient-rated Ulnar Nerve Evaluation and the common impairment measures of grip strength, pinch strength, and sensation

STUDY DESIGN

Prospective cohort study.

INTRODUCTION

Grip strength, pinch strength, and sensory threshold are common evaluations used on a daily basis. Identifying how these variables relate to function for patients allows these assessments to be used for screening to identify who may benefit from surgical intervention, and provides valuable information about what impairments patients think are important with respect to functional use of their upper extremity. Therapists can use this information to focus rehabilitation programs on the most important impairments.

PURPOSE

To evaluate the relationship between the Patient-rated Ulnar Nerve Evaluation (PRUNE) and impairment measures of grip strength, pinch strength, and one-point sensory threshold.

METHODS

Data was prospectively collected from 77 patients before surgery and during regular time points for 2 years following surgery. Patients completed the PRUNE, grip and pinch strength measures, and a one-point sensory threshold evaluation. Correlations between these variables were calculated at baseline, 2 years after surgery, and for change scores during the 2-year follow up. A multiple regression analysis was used to determine the contribution of the impairment variables for determining functional change.

RESULTS

Grip strength showed moderate, statistically significant correlation with PRUNE scores at both baseline (r = -0.38) and at two years (r = -0.29). There was also a statistically significant correlation between one point sensory threshold for the small finger at two years (r = 0.36), but not at baseline. Change in grip strength (r = -0.28) and pinch strength (r = -0.30) both demonstrated significant correlations with PRUNE change scores. Overall, changes in grip strength, pinch strength, and sensation accounted for 20% of the variance in PRUNE changes.

CONCLUSION

Since grip strength was most highly correlated with PRUNE scores at baseline and at two years, rehabilitation programs that target grip strengthening is supported. While neither grip nor pinch strength were significant contributors to the regression when used together, each showed significant contributions to PRUNE variability when used in the model independently. Therefore, a combination of grip and pinch strengthening may be important during rehabilitation for improving functional results in patients that undergo surgical intervention for cubital tunnel syndrome.

LEVEL OF EVIDENCE

2b.

Hemiarthroplasty of the elbow: the effect of implant size on joint congruency

BACKGROUND

Distal humeral hemiarthroplasty is a treatment option for elbow joint disease that predominantly affects the distal humerus, including distal humerus fractures, nonunions, and avascular necrosis. The effect of hemiarthroplasty implants on joint contact has not been reported. The purpose of this in vitro study was to quantify the effects of hemiarthroplasty and implant size on ulnohumeral joint congruency.

METHODS

Five fresh frozen cadaveric upper extremities were mounted to a custom elbow testing system. Active and passive motion were performed in dependent, horizontal, varus, and valgus positions. A registration and interbone distance algorithm was used to quantify ulnohumeral joint congruency throughout elbow flexion.

RESULTS

The optimally sized hemiarthroplasty implant demonstrated the greatest joint congruency with the ulna, followed by the oversized implant, then the undersized implant. Joint congruency was greater during active vs. passive flexion, indicating that the elbow joint is more reduced in active flexion than in passive flexion.

CONCLUSION

This study demonstrates that undersized distal humeral hemiarthroplasty implants have the lowest joint congruency compared with an optimally sized or oversized implant.

A biomechanical assessment of fixation methods for a coronoid prosthesis

BACKGROUND

The coronoid process is an integral component for maintaining elbow joint stability. When fixation of a fracture is not possible, prosthetic replacement may be a feasible solution for restoring stability. The purpose of this in-vitro biomechanical study was to compare fixation methods for a coronoid implant.

METHODS

A coronoid prosthesis was subjected to distally-directed tip loading after implantation using four fixation methods: press-fit, anterior-to-posterior screws, posterior-to-anterior screws, and cement. Testing was performed on seven fresh-frozen ulnae in a repeated-measures model. Rounds of cyclic loading were applied at 1 Hz, for 100 cycles, increased in 50 N increments up to a maximum of 400 N. Micro-motion of the implant was quantified using an optical-tracking system. Outcome variables included total displacement, distal translation, gapping, anterior translation and axial stem rotation.

FINDINGS

Cement fixation reduced implant micro-motion compared to screw fixation, while the greatest implant micro-motion was observed in press-fit fixation. Comparing screw-fixation techniques, posterior-anterior screws provided superior stability only in distal translation. The implant did not experience displacements exceeding 0.9 mm with screw or cement fixation.

INTERPRETATION

Cement fixation provides the best initial fixation for a coronoid implant. However, the stability provided by both methods of screw fixation may be sufficient to allow osseous integration to be achieved for long-term fixation. Large displacements were observed using the press-fit fixation technique, suggesting that modifications would need to be developed and tested before this technique could be recommended for clinical application.

Regional Variations in Cartilage Thickness of the Radial Head: Implications for Prosthesis Design

PURPOSE

To characterize the regional variations in cartilage thickness around the radial head.

METHODS

We dissected 27 cadaveric radii and scanned them with computed tomography in neutral position. Three-dimensional cartilage and subchondral bone surface models were generated from computed tomography scans and 2 independent observers processed them through a computer program to obtain cartilage thickness measurements. These measurements were taken at 41 predetermined landmarks around the periphery of the radial head and within the articular dish.

RESULTS

At the periphery of the radial head, cartilage was thickest in the posteromedial region. Thickness values within the articular dish were similar but increased toward the rim. Regional variations within the rim (range, 0.76-1.73 mm) were also detected with the thickest region located anteriorly and thinnest region laterally. In addition, cartilage was significantly thicker in male relative to female specimens.

CONCLUSIONS

Regional variations in cartilage thickness are present around the periphery and rim and within the articular dish of the radial head.

CLINICAL RELEVANCE

Cartilage thickness across the articular dish may contribute to dish depth and the radius of curvature. This may be clinically important for the design of anatomic implants, because accounting for such subtle contours could help to restore radiocapitellar concavity-compression stability better.

A structured review addressing the use of radiographic measures of alignment and the definition of acceptability in patients with distal radius fractures

BACKGROUND

Standard radiographs are routinely used in clinical care to characterize the severity of a distal radius fracture and to monitor patients following a distal radius fracture. The objective of this review was to describe the range and variability of radiographic measures described in the literature in patients following a distal radius fracture.

METHODS

A structured literature review was conducted using the Embase and PubMed databases. Inclusion criteria included full-text publications which employed radiographic measures to examine 100 or more participants following a distal radius fracture. A standardized data extraction form was used to identify study design, fracture classification systems, the types of and definitions of radiographic measurements, and acceptability criteria following distal radius fractures.

RESULTS

From an initial 263 studies, 31 studies were included in the final data extraction process. A narrative synthesis of the articles included in this review indicated that there was a set of commonly used radiographic measurements examined in patients with a distal radius fracture which included radial inclination, volar/dorsal tilt, intra-articular step/gap, and a measure of ulnar variance/radial shortening. While 52 % of studies referenced or published a standardized measurement technique, there was substantial variability in the actual description of each radiographic measurement performed.

CONCLUSIONS

Substantial variability in how radiographic measurements are defined in large clinical studies as seen in this review suggest a need for consensus on the assessment and interpretations of radiographic measures used in patients following a distal radius fracture. Guidelines for radiographic measures should be established to ensure consistency between research and treatment centers.