Ulnar coronoid process anatomy: possible implications for elbow instability

Biomechanical evaluation of the modified lasso technique

BACKGROUND

The Terrible Triad of the elbow is a constellation of elbow dislocation, radial head fracture and coronoid process fracture. A common type of coronoid fracture documented with this triad is type II Regan-Morrey coronoid fractures. The preferred fixation method for this fracture type is the lasso technique, medial-lateral tunnel orientation being the traditional approach. Considering elbow anatomy, we saw an opportunity to potentially improve fixation by altering the suture lasso tunnel orientation to a proximal-distal orientation.

HYPOTHESIS

Two tunnels in the proximal-distal direction would result in greater biomechanical stability as compared to the traditional lasso technique.

MATERIAL AND METHODS

A type 2 Regan-Morrey fracture was created in 12 fresh frozen cadaveric elbows at 50% of the coronoid height using an oscillating saw. The humero-ulnar joint was placed in 0 degrees flexion then loaded at a rate of 10mm/min to failure.

RESULTS

The control technique (medio-lateral tunnels) showed failure load of 150±81N that was not significantly different (p=0.825) than the 134±116N measured for the modified technique (distal-proximal tunnels). The portion of the load-displacement curve used to calculate stiffness was linear (R^2=0.94±0.04) with determination coefficients that did not differ between the two groups (p=0.351). For stiffness, we measured 17±13N/mm and 14±12N/mm respectively for control and modified techniques that did not result in a significant difference (p=0.674).

CONCLUSION

In this attempt to improve the shortcomings of the lasso technique, we found that changing from medio-lateral to proximal-distal drilling directions did not result in an appreciable biomechanical benefit.

LEVEL OF EVIDENCE

Basic science study; Biomechanics.

Coronoid fractures and traumatic elbow instability

The coronoid process is key to concentric elbow alignment. Malalignment can contribute to post-traumatic osteoarthritis. The aim of treatment is to keep the joint aligned while the collateral ligaments and fractures heal. The injury pattern is apparent in the shape and size of the coronoid fracture fragments: (1) coronoid tip fractures associated with terrible triad (TT) injuries; (2) anteromedial facet fractures with posteromedial varus rotational type injuries; and (3) large coronoid base fractures with anterior (trans-) or posterior olecranon fracture dislocations. Each injury pattern is associated with specific ligamentous injuries and fracture characteristics useful in planning treatment. The tip fractures associated with TT injuries are repaired with suture fixation or screw fixation in addition to repair or replacement of the radial head fracture and reattachment of the lateral collateral ligament origin. Anteromedial facet fractures are usually repaired with a medial buttress plate. If the elbow is concentrically located on computed tomography and the patient can avoid varus stress for a month, TT and anteromedial facet injuries can be treated nonoperatively. Base fractures are associated with olecranon fractures and can usually be fixed with screws through the posterior plate or with an additional medial plate. If the surgery makes elbow subluxation or dislocation unlikely, and the fracture fixation is secure, elbow motion and stretching can commence within a week when the patient is comfortable.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Greater sigmoid notch dysplasia causing elbow instability: Lateral ligament reconstruction and Stamp osteotomy

The coronoid is one of the elbow's primary static stabilisers, and the importance of reconstruction following fracture with instability has been established. In the developing elbow, instability can lead to greater sigmoid notch dysplasia that can make reconstruction challenging. A novel technique to improve osseous stability with an opening wedge 'stamp osteotomy' reconstruction of the coronoid is described combined with a lateral ligament reconstruction, in two patients with recurrent posteromedial rotatory instability. The technique improves congruity and coverage of the greater sigmoid notch with the trochlea whilst maintaining articular cartilage. Extra-articular iliac crest bone graft is used to maintain the position with buttress plate support. The surgical technique is described and the clinical and radiographic outcome reported in two patients. Level of evidence: IV.

Histologic Evaluation of the Triceps Brachii Tendon Insertion: Implications for Triceps-Sparing Surgery

PURPOSE

Triceps detachment and olecranon osteotomy are 2 techniques used to enhance exposure in elbow surgery. Both the techniques can potentially add considerable morbidity and lengthen the recovery after surgery. Triceps-sparing surgery can potentially mitigate those issues. The purpose of this study was to evaluate the triceps tendon insertion at a histologic level to help improve triceps-sparing surgical techniques used in elbow trauma and arthroplasty.

METHODS

Seventeen fresh-frozen cadaveric elbow specimens were collected. The olecranon and its soft tissue attachments were isolated. We performed gross measurements and sectioned the specimens for histologic evaluation in the saggital or coronal planes. The proximal-to-distal and medial-to-lateral dimensions of the tendon and the distance from the proximal tip of the olecranon to the proximal tendon insertion were measured microscopically on stained embedded sections.

RESULTS

The proximal-to-distal dimension of the triceps tendon insertion was less than previously reported, whereas the medial-to-lateral dimension was similar. The true distance from the tip of the olecranon to the proximal tendon insertion was greater than the previously reported distance obtained via gross measurement.

CONCLUSIONS

Gross measurement of the triceps tendon insertion overestimates and inaccurately represents the true insertional footprint. Gross measurement has been shown to demonstrate consistent disparity compared with histologic measurement. Histologic investigation provides a more accurate description.

CLINICAL RELEVANCE

The finding that the distance from the articular tip of the olecranon to the proximal tendon insertion is greater than previously reported may have clinical implications. A triceps split approach may allow more visualization and exposure of the posterior joint and, therefore, lessen the need for triceps detachment or olecranon osteotomy.

Reconstruction of the coronoid process with the olecranon tip for chronic elbow dislocation in children: A rare case report and literature review

The coronoid process of the ulna, as a key part of the elbow joint, plays an important role in maintaining elbow joint stability. Reconstruction of the coronoid process is necessary in both acute and chronic coronoid defects to restore elbow stability and avoid early joint degeneration. The olecranon tip may be a useful autologous osteochondral graft for reconstructing the same shape of the ulna coronoid process. The purpose of this report was to verify if reconstruction of the coronoid process with the olecranon tip can restore elbow stability and kinematics. Here, we report a 13-year-old boy who had undergone Kirschner-wire fixation for a left supracondylar fracture of the left humerus 9 years previously. After that, the right elbow dislocation and varus deformity gradually appeared. Imaging revealed posterolateral dislocation of the left elbow due to the absence of the coronoid process of the ulna. We reconstructed the ulnar coronoid process by intercepting the ipsilateral olecranon tip. After 22 months of follow-up, the range of motion of the left elbow joint was normal, and the cubitus varus deformity disappeared. The results of this report suggest that olecranon tip autografts are suitable to replace transverse coronoid defects. Given the patient's satisfactory clinical results, this reconstruction technique is safe and effective for the treatment of chronic elbow instability due to coronoid process defects of the ulna.

Repair Versus Non-Repair of Lateral Ulnar Collateral Ligament in Elbow Varus Posteromedial Rotatory Instability Treatment: A Comparative Study

OBJECTIVE

To compare the effects of repairing and not repairing the lateral ulnar collateral ligament (LUCL) when surgically treating elbow varus posteromedial rotatory instability (PMRI).

METHODS

In this retrospective study spanning June 2014 to February 2019, 24 patients with elbow PMRI who were treated surgically were assigned to group RL (Repair LUCL) or group NL (Non-repair LUCL) depending on whether the LUCL was repaired. Hospitalization time, operation time, intraoperative blood loss, and related complications were reviewed. The elbow range of motion (ROM), the visual analog scale (VAS), the Mayo elbow performance score (MEPS), and the disabilities of the arm, shoulder, and hand (DASH) score were used for functional assessment.

RESULTS

Among the 24 patients with PMRI, 15 were assigned to group RL and nine were assigned to group NL. The mean blood loss (184.66 ± 20.3 vs 207.33 ± 19.447, P < 0.001), the operation time (98.88 ± 12.693 min vs 184.66 ± 20.3 min, P < 0.001) were significantly lower in group RL compared to group NL. There were no significant differences between the two groups in time until surgery and follow-up time (6.66 ± 1.838 vs 6.11 ± 1.900 days, 25.53 ± 2.099 vs 26.11 ± 2.891 months, P = 0.577, P = 0.486). All of the patients achieved bone union. The elbow flexion-extension ROM (122.00° ± 3.162°vs 121.11° ± 3.333° at 12 months, P = 0.520) and pronation-supination ROM (154.53° ± 3.335° vs 155.55° ± 4.639° at 12 months, P = 0.537). Both groups achieved similar results in MEPS score (90.53 ± 2.695 vs 89.77 ± 3.865, P = 0.578) and DASH (9.77 ± 1.897 vs 9.99 ± 1.550, P = 0.772) score at the final follow-up. And the MEPS score revealed excellent results (87% in group RL, 89% in group NL).The VAS scores decreased significantly in group RL (from 6.13 ± 0.990 to 1.93 ± 0.593) and group NL (from 5.77 ± 1.481 to 1.88 ± 0.781), and no significant differences in preoperative or final follow-up were observed between the two groups (P = 0.487, P = 0.876). Complications observed in group NL with one patient occurred cubital tunnel syndrome 3 months after the operation, the patient underwent ulnar nerve simple neurolysis and the symptoms were relieved after 3 weeks.

CONCLUSION

For patients with elbow PMRI, satisfactory functional outcomes can be yielded with non-repair of the LUCL as long as the stable elbow joint is performed during operation.

Reconstruction of coronoid process of the ulna: a literature review

As a pivotal part of the elbow joint structure, the coronoid process of the ulna plays a vital role in maintaining elbow joint stability. Loss of coronoid process height causes instability of the elbow joint depending on the fracture characteristics and size. The diagnosis and treatment of coronoid process fractures has gained widespread attention from orthopedic surgeons. Nevertheless, few reports have described reconstruction of coronoid process fractures and defects that affect elbow joint stability. Treatment of elbow joint instability induced by coronoid process defects is challenging because most cases are complicated by other elbow joint injuries. Moreover, the clinical efficacy remains unclear. The present narrative review was performed to examine the research progress on reconstruction of the coronoid process. The findings of this review provide evidence for clinical repair and reconstruction of coronoid process defects and contribute to the published literature on this topic.

Monteggia-like lesions: preliminary reports and mid-term results of a single center

Background and aim of the work:

Monteggia-like lesions are complex and rare elbow injuries. A detailed classification and a proper surgical treatment can provide quite good functional and radiological outcomes. The aim of this retrospective study was to evaluate the mid-term results of Monteggia-like lesions surgical treatment. The other purpose was to investigate whether the complexity of ulna and radius fractures could be prognostic factors of insufficient functional results.

Methods:

Seven women and five men, with a mean age of 59,25 years who had sustained a Monteggia-like lesion were followed up clinically and radiologically after surgical treatment. The Mayo Elbow Performance Score (MEPS) and the Quick Disabilities of the Arm, Shoulder and Hand (QUICK-DASH) score were used for evaluation at a mean of 17,5 months postoperatively (12-26). The range of movement (ROM), patients’ satisfaction and neurological symptoms were also investigated. Osteolysis, implant loosening and heterotopic ossification were graded. Pearson’s test was used to correlate the different classification systems used (AO/OTA, Bado and Jupiter, PURCCS, Mason) with MEPS and QUICK-DASH score.

Results:

The mean MEPS was 84,92 (65 to 100). The mean QUICK-DASH score was 18,75 (0 to 34,1). The mean active pronation and supination was 72,5° and 59,17°, respectively. The mean active ROM of the elbow was 101,43°. Heterotopic ossifications were absent in six cases but were found in six. No statistically significant correlation was found between the analyzed variables.

Conclusions:

Quite good functional results can be obtained in Monteggia-like lesions if injury pattern is recognized and each component of the injury is addressed. Further studies are needed to determine any prognostic factors. (www.actabiomedica.it)

Functional Outcome of Surgically Treated Isolated Coronoid Fractures With Elbow Dislocation in Young and Active Patients

Coronoid fractures are less frequent injuries seen in around one-tenth of patients with elbow dislocation. Any injury to the coronoid process can be associated with elbow instability, in which injury to collateral ligaments co-exists, resulting in a loss of congruency of the elbow joint. However, there is a scarcity of evidence regarding patients' management with elbow dislocation and associated coronoid fractures. So, our aim is to assess the functional outcome of the elbow after operative fixation in patients with any type of coronoid fracture with associated elbow dislocation. A total of six patients with closed coronoid fracture of the elbow, with associated elbow dislocation, without any other associated trauma or previous surgery to the same limb, were included in our study. After closed reduction, patients with an incongruent reduction of the elbow joint were operated. The injured structures were repaired in an inside-out sequence: the coronoid fragment was first reduced by using a lasso-type suture. The larger fragments of the coronoid were fixed with either a screw or a plate when deemed necessary. Then, the lateral collateral ligament was repaired either using a suture anchor or transosseous (No. 2 Arthrex; Naples, Florida) sutures.

After repair, the elbow was examined for stability radiologically using the hanging arm test; a concentric reduction of the elbow in lateral view during this test indicates a stable elbow. All patients showed a good to excellent outcome on the Mayo elbow performance score (MEPS) at the final follow-up (three patients had an excellent score while three had a good score). At the final follow-up, mean elbow flexion was 124º, loss of extension was 10º in only one patient, mean supination was 80º, and mean pronation was 72º. Isolated fractures of the coronoid associated with elbow dislocation require appropriate evaluation and management. Closed reduction and immobilization alone in young and active patients may not be sufficient, especially in patients with incongruent ulnohumeral joint. Surgical fixation of the coronoid fragment and repair of the collateral ligament, whenever indicated, can provide good functional outcomes.

Reliability and validity of the Wrightington classification of elbow fracture-dislocation

Aims

The Wrightington classification system of fracture-dislocations of the elbow divides these injuries into six subtypes depending on the involvement of the coronoid and the radial head. The aim of this study was to assess the reliability and reproducibility of this classification system.

Methods

This was a blinded study using radiographs and CT scans of 48 consecutive patients managed according to the Wrightington classification system between 2010 and 2018. Four trauma and orthopaedic consultants, two post CCT fellows, and one speciality registrar based in the UK classified the injuries. The seven observers reviewed preoperative radiographs and CT scans twice, with a minimum four-week interval. Radiographs and CT scans were reviewed separately. Inter- and intraobserver reliability were calculated using Fleiss and Cohen kappa coefficients. The Landis and Koch criteria were used to interpret the strength of the kappa values. Validity was assessed by calculating the percentage agreement against intraoperative findings.

Results

Of the 48 patients, three (6%) had type A injury, 11 (23%) type B, 16 (33%) type B+, 16 (33%) Type C, two (4%) type D+, and none had a type D injury. All 48 patients had anteroposterior (AP) and lateral radiographs, 44 had 2D CT scans, and 39 had 3D reconstructions. The interobserver reliability kappa value was 0.52 for radiographs, 0.71 for 2D CT scans, and 0.73 for a combination of 2D and 3D reconstruction CT scans. The median intraobserver reliability was 0.75 (interquartile range (IQR) 0.62 to 0.79) for radiographs, 0.77 (IQR 0.73 to 0.94) for 2D CT scans, and 0.89 (IQR 0.77 to 0.93) for the combination of 2D and 3D reconstruction. Validity analysis showed that accuracy significantly improved when using CT scans (p = 0.018 and p = 0.028 respectively).

Conclusion

The Wrightington classification system is a reliable and valid method of classifying fracture-dislocations of the elbow. CT scans are significantly more accurate than radiographs when identifying the pattern of injury, with good intra- and interobserver reproducibility. Cite this article: Bone Joint J 2020;102-B(8):1041–1047.

Anterior capsule re-attachment in terrible triad elbow injury with coronoid tip fracture

BACKGROUND

During the surgical treatment of terrible triad elbow injury (TTEI), the usefulness of re-attaching the anterior joint capsule when the coronoid tip is fractured remains unclear. The primary objective of this study was to assess potential benefits during surgery for TTEI of re-attaching the joint capsule when the coronoid tip is fractured.

HYPOTHESIS

Re-attaching the anterior joint capsule in TTEI with a fractured coronoid tip improves clinical and radiological outcomes and decreases the complication and revision rates.

MATERIALS AND METHODS

This single-centre retrospective study included patients who underwent surgery at the acute phase of TTEI with a fractured coronoid tip. In all patients, a physical examination and elbow radiographs were performed at least 1year after surgery. A statistical analysis was done to compare the groups with vs. without re-attachment of the anterior capsule and coronoid tip.

RESULTS

The study included 30 patients, 16 females and 14 males, with a mean age of 51years (range: 21-84years). Among them, 11 did and 19 did not undergo re-attachment. The two groups were comparable regarding demographic features and follow-up duration. No significant differences were found at last follow-up for flexion-extension motion arc (p=0.75), pronation-supination motion arc (p=0.3051), or the Mayo Elbow Performance Score (p=0.19). Radiographic evidence of humero-radial osteoarthritis was significantly more common in the absence of re-attachment (p=0.04), whereas no differences were evidenced regarding humero-ulnar osteoarthritis (p=0.73), the occurrence of subluxation or dislocation (p=0.43), or loosening of the radial head implant (p=0.47). The complication and revision rates were similar in the two groups.

CONCLUSION

In our experience, re-attaching the anterior capsule during the surgical treatment of TTEI with a coronoid tip fracture did not improve the clinical or radiographic outcomes after a mean follow-up of 54months.

LEVEL OF EVIDENCE

IV, retrospective study.

Insertional anatomy of the anterior medial collateral ligament on the sublime tubercle of the elbow

BACKGROUND

Acute injuries to the anterior medial collateral ligament (AMCL) can occur due to valgus trauma or during other dislocating events to the elbow. AMCL lesions are often associated with bony lesions, such as radial head fractures or fractures of the coronoid process. We analyzed the insertion of the AMCL on the sublime tubercle in relation to surrounding osseous structures. We aimed to increase the understanding of the involvement of the AMCL in bony lesions to the sublime tubercle.

METHODS

We investigated 86 elbows from 43 embalmed human specimens. We measured the most ventral extensions of the AMCL at the sublime tubercle in relation to a clearly defined and reproducible landmark. We used as our landmark a horizontal line (baseline) originating on the lesser sigmoid notch in a right angle to the ulnar ridge.

RESULTS

The mean distance of the coronoid process tip to the baseline was 4.0 mm (standard deviation [SD], 1.3 mm; range, 1.4-6.7 mm). The mean distance of the ventral extension of the AMCL to the horizontal line was 3.7 mm (SD, 2.6 mm; range: 9.4-2.2 mm). The mean horizontal distance between the ventral aspect of the AMCL and the coronoid tip was 13.7 mm (SD, 2.5 mm; range, 7.7-20.5 mm).

CONCLUSIONS

We present a detailed description of the insertional anatomy of the AMCL at the sublime tubercle. These values could be helpful for classifications of coronoid fractures and to estimate the involvement of the AMCL in fractures of the sublime tubercle.

Quantitative measurements of facets on the ulnar coronoid process from reformatted CT images

Background

To quantify the size and angle of the medial and lateral facets of the ulnar coronoid process by reformatted computed tomography (CT) imaging.

Methods

Elbow CT images were retrospectively selected from the picture archiving and communication system in our hospital over a 5-year period (January 2011 to December 2015). The widths, heights, gradient and tilt angles of both the medial and lateral facet of the ulnar coronoid process were measured using two-dimensional (2D) reformations of CT images.

Results

Our database research yielded 120 elbow joints (53 right, 67 left) of 120 patients (54 males, 66 females) which fulfilled our criteria. The average width of the two facets of the ulnar coronoid process were 13.34±1.85 mm for the medial facet and 8.39±1.29 mm for the lateral facet. The average height of the medial facet was 18.45±3.38 mm and the lateral facet was 17.55±3.81 mm. The average tilt angles of medial and lateral facet were 80.34°±7.71° and 98.78°±5.71° respectively. The average gradient angles of the medial and lateral facet ridge were 60.02°±8.78° and 36.97°±4.99° respectively. The length of the lateral facet ridge was longer than the medial facet ridge.

Conclusions

Reformatted CT images allow for multiple, accurate measurements of facets on the ulnar coronoid process. These measurements can be applied to guiding appropriate surgical interventions for fractures in this area.

Lasso plate - An original implant for fixation of type I and II Regan-Morrey coronoid fractures

INTRODUCTION

Coronoid fractures are notoriously difficult to manage particularly when there is a small fragment. We report a retrospective analysis of our experience with consecutive type I and II Regan-Morrey coronoid fractures using a lasso plate.

HYPOTHESIS

Type I and II Regan-Morrey coronoid fractures can be effectively managed using a lasso plate.

METHODS

From October 2011 and December 2013, 25 patients (21 males and 4 females, mean age 40.0 years) with type I and II Regan-Morrey coronoid fractures were treated with the open reduction and internal fixation (ORIF) using the lasso plate. Postoperative measurements of the elbow range of motion were recorded. Elbow function was evaluated by the Mayo Elbow Performance Score (MEPS) and Disabilities of the Arm, Shoulder and Hand (DASH) score.

RESULTS

All patients were reexamined at a mean follow-up of 32.7 months (range: 24-49 months). The mean fractures healing time was 13.6 weeks (range: 6 to 18 weeks). The mean flexion range of the elbow was 121.8° (range: 90° to 135°) and the mean extension range of the elbow was 10.6° (range: 0° to 20°). The mean pronation of the forearm was 75.8° (range: 65° to 85°). The mean supination of the forearm was 80.4° (range: 70° to 90°). The mean DASH score was 10.2 (range: 0 to 28). The mean MEPS was 83.4 (range: 55 to 95), 8 patients (32%) were rated excellent, 14 patients (56%) were rated good, 2 (8%) patients were rated fair. One (4%) patient was rated poor. No patient was seriously infected but implant breakage was found in one case. Two cases of elbow heterotopic ossification (HO) were observed. Two cases of elbow medial instability were observed.

DISCUSSION

The type I and II Regan-Morrey coronoid fractures combined with the instability of the elbow should be operated. The lasso plate reduces the pressure between the wire and the insertion of capsule. A tight wire results in greater stability than ordinary suture fixation, thus enabling early functional exercise.

CONCLUSION

In the treatment of type I and II Regan-Morrey coronoid fractures, lasso plate can provide concentric fracture reduction of the elbow and stable fixation to allow for early rehabilitation. Good clinical outcomes can be anticipated.

LEVEL OF EVIDENCE

Level IV: retrospective study.

Joint capsule attachment to the coronoid process of the ulna: an anatomic study with implications regarding the type 1 fractures of the coronoid process of the O'Driscoll classification

BACKGROUND

The attachment of the anterior joint capsule on the ulnar coronoid process is not yet completely understood. The purpose of this study was to clarify the anatomic relationship between the anterior capsule of the elbow joint and the tip of the coronoid process.

METHODS

Seventeen embalmed elbows were used for this anatomic study. The anterior capsule of the elbow joint was reflected, and the attachment of the capsule on the coronoid process was exposed. The attachment of the joint capsule on the coronoid process was macroscopically and histologically observed, its relationship to the coronoid tip was assessed, and the length of the attachment of the joint capsule was measured.

RESULTS

The length of the capsule attachment at the radial side of the coronoid (11.9 mm) was greater than that at the ulnar side (6.1 mm). The bone thickness on the coronoid tip from the proximal edge of the joint capsule attachment was 1.9 mm; together, the cartilage and bone thickness was 4.7 mm. At the radial side of the coronoid, the thickness of the joint capsule at the proximal aspect of the attachment of 2 samples was 0.6 mm and 0.3 mm, and that at the tip of the coronoid was 2.6 mm and 1.7 mm, respectively.

CONCLUSIONS

The anterior capsule of the elbow joint had a substantial attachment on the radial side of the coronoid process. The subtype 2 tip fractures of the O'Driscoll classification included the joint capsule attachment, joint cartilage, and subchondral bone.

Reconstruction of Monteggia-like proximal ulna fractures using different fixation devices: A biomechanical study

BACKGROUND

Comminuted proximal ulna fractures are rare and reconstruction of these fractures is discussed controversially. The aim of this study was to test three currently available plate devices in a standardized comminuted four-part fracture model created in proximal ulna sawbones.

MATERIAL AND METHODS

A standardized four-part fracture of the proximal ulna was created in 80 sawbones. Reconstruction was performed by five experienced test surgeons according to a standardized reconstruction protocol. Each surgeon reconstructed 4 fractures with a 3.5mm eight-hole reconstruction plate, 4 fractures with seven-hole third-tubular double plates and 4 fractures with a 3.5mm anatomical seven-hole locked angle proximal ulna plate. 4 more fractures were reconstructed with simple K-wires as a reference construct for further experiments. Outcome measurements were time for reconstruction, quality of reconstruction and stability of the reconstruction. Stability testing was done in 90° and 30° flexion of the elbow. Testing in 30° flexion was done to test the anteroposterior stability regarding the fixed coronoid process.

RESULTS

Time for reconstruction was significantly less for K-wire fixation than for the plate devices. Time for reconstruction plating and locked angle plating was significantly lower than for double plating (p<0.005). Quality of reduction did not differ between the three plate systems (p<0.05). K-wire fixation showed the best quality of reduction (p<0.005). In 90° of elbow flexion the anatomic locked angle olecranon plate showed a significantly higher stability compared to the other devices. Furthermore the tubular double plating was significantly more stable than reconstruction plating or K-wire fixation (p<0.05). In anteroposterior loading at 30°, the stability did not differ between the 4 different fixation techniques (p>0.05). For all devices the testing in 30° flexion showed a significantly higher rigidity compared to 90° flexion.

CONCLUSION

The locked angle plate system showed the highest stability in 90° of elbow flexion. Each implant was more stable in 30° flexion than in 90° flexion. Testing of the anterior stability of the elbow did not show any differences between the different implants. Because of the superior stability of this device, we conclude that locked angle plating should be preferred for reconstruction of monteggia like complex proximal ulna fractures.

Effect of elbow flexion angles on stress distribution of the proximal ulnar and radius bones under a vertical load: measurement using resistance strain gauges

Objectives

This study aimed to explore the surface stress at the proximal ends of the ulna and radius at different elbow flexion angles using the resistance strain method.

Methods

Eight fresh adult cadaveric elbows were tested. The forearms were fixed in a neutral position. Axial load increment experiments were conducted at four different elbow flexion angles (0°, 15°, 30°, and 45°). Surface stain was measured at six sites (tip, middle, and base of the coronoid process; back ulnar notch; olecranon; and anterolateral margin of the radial head).

Results

With the exception of the ulnar olecranon, the load-stress curves at each measurement site showed an approximately linear relationship under the four working conditions studied. At a vertical load of 500 N, the greatest stress occurred at the middle of the coronoid process when the elbow flexion angles were 0° and 15°. When the flexion angles were 30° and 45°, the greatest stress occurred at the base of the coronoid process. The stress on the radial head was higher than those at the measurement sites of the proximal end of the ulna.

Conclusion

The resistance strain method for measuring elbow joint surface stress benefits biomechanics research on the elbow joint. Elbow joint surface stress distributions vary according to different elbow flexion angles.

Elbow ulnar collateral ligament reconstruction: clinical, radiographic, and ultrasound outcomes at a mean 3-year follow-up

BACKGROUND

Ulnar collateral ligament (UCL) has the main function to be stress-resistant to elbow valgus overload. Multilayer tears require a reconstruction with a tendon graft. In this study, we report the clinical, radiographic, and ultrasound outcomes after tendon graft reconstruction for symptomatic UCL insufficiency.

MATERIALS AND METHODS

Among twenty-six subjects underwent elbow UCL reconstruction from 2006 to 2012, fifteen were available to be evaluated at a mean follow-up of 36 months. Preoperative assessment included clinical examination and MRI. The outcome measures were the Mayo Elbow Performance Score (MEPS); the Oxford Elbow Score (OES); the Disabilities of the Arm, Shoulder, and Hand (DASH); and the Conway-Jobe Scale. Overall population was postoperatively investigated with X-ray and ultrasound (US). Reconstruction was performed with autograft (palmaris longus) in five cases and allograft (semitendinosus) in ten cases using the figure-of-eight configuration (five cases), the docking technique (eight cases), or a fixation with screws (two cases).

RESULTS

We found a significant improvement in postoperative MEPS, OES, and DASH scores (p < 0.01). One case was unsatisfied and required an additional procedure of ulnar nerve transposition 12 months after the reconstruction. X-ray showed calcifications along the graft in ten cases. At US examination, all the grafts assessed appeared anatomically intact without structural changes, and the dynamic examination showed a slight medial laxity with the valgus stress maneuver without pain or other sign of medial instability.

CONCLUSIONS

This study confirms the efficacy of the graft reconstruction for chronic UCL insufficiency and introduces fresh insight on the role of musculoskeletal ultrasound to evaluate the reconstructed UCL.

Anterior approach for fixation of isolated type III coronoid process fracture

Authors chose anterior approach through the antecubital fossa for better exposure in that case of isolated coronoid process fracture. The objective of the study was to report validity of anterior approach for the Regan and Morrey type III, isolated fracture of the coronoid process of the ulna without residual valgus or varus instability. From January 2007 and January 2010, we evaluated eleven consecutive patients (7 men, 4 women; mean age 44 years; range 25-67 years) who underwent surgical fixation through the anterior approach. The mean follow-up period was 21 months (range 15-34 months). Preoperative and follow-up roentgenograms were evaluated for assessment of the fracture configuration and confirmation of fracture union. Clinical evaluation included an analysis of surgical complication, range of motion, Mayo elbow performance score, and DASH (disability of the arm, shoulder, and hand) score. Fractures were mainly fixed with plate and screws in 8 cases, cannulated screws in 3 cases. There was no residual joint instability after fracture fragment fixation. All fractures were united, and the average union time was 15.2 weeks with a range of 11-20 weeks. Mean flexion contracture of the elbow was 3.6° (range 0°-10°), and further flexion was 130.9° (range 125°-140°) at the last follow-up. Mean Mayo elbow performance score was 92.3 (range 80-100 points), and mean DASH score was 5.9 (range 1.6-8.3 points). In conclusion, Primary fixation of the coronoid process fractures through the anterior approach could be particularly useful in the Regan and Morrey type III isolated coronoid process fractures.

Surgical reconstruction of comminuted coronoid fracture in terrible triad injury of the elbow

The terrible triad injury of the elbow is the combination of an elbow dislocation, a radial head fracture and a coronoid process fracture. In this study, we explored the outcome of a modified protocol for terrible triad injury of the elbow in a consecutive series of 14 patients, with a focus on reconstruction of comminuted coronoid fractures. Fourteen patients with terrible triad injuries of the elbow were retrospectively reviewed at a mean follow-up of 23 months (range, 15-30 months) and were clinically and radiographically evaluated. For comminuted coronoid fractures, autografting with resected radial head fragment or ilium fragment with cartilage surface and transosseous suture with non-absorbable suture were performed. Internal fixation of the radial head was performed in six cases and arthroplasty in five. The collateral ligaments were repaired. Mean flexion at last follow-up was 125°, ranging from 100° to 135°. Mean extension loss was 13°, ranging from 0° to 38°. Mean pronation was 70° and mean supination was 66°. No patient experienced dislocation of the radial head prosthesis. The mean Mayo Elbow Performance Score (MEPS) was 87 (range, 75-100), with six excellent cases and eight good cases. According to our intraoperative examination, no patient demonstrated unacceptable residual instability in extension following restoration of all of the osseous and ligamentous lesions. In conclusion, our protocol can achieve stable reconstruction of the coronoid process, which promotes the functional outcome of surgical treatment on terrible triad injuries of the elbow.

An anatomic study of coronoid cartilage thickness with special reference to fractures

BACKGROUND

Current coronoid fracture classification systems are based on fragment size and configuration using plain radiographs and/or computed tomography (CT). During surgery, coronoid fracture fragments appear much larger than anticipated because cartilage is radiolucent and therefore not accounted for with preoperative imaging. The purpose of this imaging study was to quantify the articular cartilage thickness of the coronoid, with reference to coronoid fractures.

MATERIALS AND METHODS

Twenty-four cadaveric ulnae were dissected, imaged with CT, and analyzed by use of image analysis software. Thirteen identifiable landmarks were chosen on the coronoid, olecranon, and proximal radioulnar joint to measure articular cartilage thickness. Intraobserver reliability and interobserver reliability were determined.

RESULTS

Cartilage thickness was highest at the coronoid tip, with a mean of 3.0 mm (range, 1.7-4.6 mm). Cartilage thickness at the tip correlated inversely with age (P < .01) and correlated strongly with overall ulnar height and ulnar length (P < .05). All measurements had excellent intraobserver and interobserver reliability.

CONCLUSION

The thickness of cartilage on the coronoid tip is not inconsequential. The results of this study indicate that a 2-mm coronoid tip fracture on CT scan may actually appear to be a mean of 5 mm thick when viewed at the time of surgery. Clinically, this is important because it may alter the classification, the decision to treat, or the type of fixation used. Importantly, biomechanical cadaveric studies assessing coronoid injuries have incorporated cartilage thickness into coronoid size measurements when creating simulated fractures; therefore, it is critical that the conclusions of such biomechanical studies be scrutinized with regard to their clinical recommendations. Surgeons should be aware of these discrepancies.

Fractures of the coronoid: morphology based upon computer tomography scanning

HYPOTHESIS/BACKGROUND

Coronoid fractures have traditionally been described by the Regan-Morrey classification system, based upon lateral plain film radiographs. However, use of computer tomography (CT) scans to determine fracture morphology, define associated injuries, and make treatment plans is now commonplace. In addition, it is increasingly recognized that classification systems based upon plain film imaging studies may not be adequate to describe complex fracture patterns. The purpose of the present investigation was to review CT scans obtained for elbow trauma to describe coronoid fracture morphology and determine inter- and intra-observer reliability.

METHODS

CT scans performed for elbow trauma over a 2-year period were examined to identify coronoid fractures, and recurring patterns were sought. After patterns were identified, the scans were reviewed by 3 observers to determine inter- and intra-observer reliability.

RESULTS

Of 373 CT scans, 52 identified coronoid fractures were appropriate for review. Five common patterns were identified, including a tip type, mid-transverse type, basal type, anteromedial oblique fractures, and an anterolateral oblique type fracture that has not been well described previously. Inter- and intra-observer reliability ranged from good to very good in this series.

DISCUSSION/CONCLUSION

In this series, we describe anatomic patterns by which coronoid fractures break. Five common patterns were noted: a "tip" type fracture seen in 29% of the cases; a "mid-transverse" type fracture (24%); a "basal" type fracture (23); and 2 "oblique" type fracture patterns (24%), including an "anteromedial" type fracture (17%) and an "anterolateral" type (7%). There was a high rate of intra- and inter-observer reliability between and within 3 observers.

Treatment of fractures of the ulnar coronoid process

OBJECTIVE

To discuss the classification, management and outcome of fractures of the ulnar coronoid process.

METHODS

Retrospective analysis was carried out in 31 patients (19 men and 12 women of average age 29.8 years [range, 18-52 years]) with fractures of the ulnar coronoid process. The fractures were classified into four major groups based on the extent of injury to the ulnar coronoid process, the state of the anterior bundle of the ulnar collateral ligaments (UCL) and elbow stability. A fracture of the coronoid process less than halfway up was defined as type I (eleven cases); of the middle of the coronoid process with injury of the UCL as type II (nine cases); of the base of coronoid process with dislocation of the elbow joint, sometimes with injury of the UCL, as type III (six cases); and severe comminuted fracture of the coronoid process with elbow instability as type IV (five cases). We chose treatment according to the type of injury.

RESULTS

Follow-up was 18-72 months (average 28.6 months). All patients achieved fracture union without inflammation, neural injuries or elbow instability. One type III and two type IV patients had traumatic osteoarthritis, and two type III and two type IV developed heterotopic ossification. There was a statistically significant difference between the ranges of movement of the two-side joints in type IV.

CONCLUSION

We choose conservative treatment for type I fractures unless the bone fragment affected movement of the elbow joint, in which case we chose operative treatment so that elbow stability was not affected. Type II and type III fractures with elbow instability were reduced by internal fixation and the ligament repaired or reconstructed. In type IV cases, bone reconstruction was necessary to recover elbow stability. Proper post-operative rehabilitation can decrease the occurrence of traumatic osteoarthritis.

Treatment of persistent instability after posterior fracture-dislocation of the elbow: restoring stability and mobility by internal fixation and hinged external fixation

BACKGROUND

Long-term results after the treatment of fracture-dislocations of the elbow have often been disappointing, because of post-traumatic instability, stiffness, and early arthritis. We present the results after surgical restoration of stability in complex fracture-dislocations of the elbow using early postoperative mobilization with a hinged external fixator after internal reconstruction of the static stabilizers.

METHODS

Twenty patients with persistent instability after fracture-dislocation of the elbow were treated at a mean of 11 weeks after injury. We evaluated 17 elbows in 16 patients (mean age, 44 years) at a mean of 44 months after the definitive surgical procedure.

RESULTS

Overall, 10 of 17 elbows had a good or excellent result. The mean range of motion was 96° (SD, 23°). The mean Mayo Elbow Performance Score (MEPS) was 74 (SD, 18), and the mean Functional Elbow Score was 68 (SD, 21). Patients treated within 6 weeks after the trauma had significantly better scores, with a mean MEPS of 81 (SD, 18), than patients treated after a delay, with a mean MEPS of 62 (SD, 13). No patients had recurrent dislocation. Secondary arthritis was mainly found in the delayed-treatment group. Of 17 elbows, 7 (41%) had complications.

CONCLUSION

Surgical restoration of the static stabilizers in combination with hinged external fixation leads to satisfactory results when performed within the first 6 weeks after injury. When definite surgical stabilization is delayed more than 6 weeks, the procedure can still restore stability but the functional results are often disappointing.

The proximal ulna dorsal angulation: a radiographic study

BACKGROUND

Recognition of the proximal ulna dorsal angulation (PUDA) is important for anatomic reduction of proximal ulna fractures, nonunions, malunions, or osteotomies, especially when using newer straight precontoured ulnar plates. The purpose of this study was to characterize the PUDA in 50 patients with bilateral elbow radiographs.

MATERIALS AND METHODS

Commercial software was used to magnify 100 bilateral elbow radiographs 4 times. The PUDA was measured from the intersection of lines perpendicular to the subcutaneous border of the olecranon and the ulnar shaft. The olecranon tip-to-apex distance of the PUDA was also measured. Three orthopedic surgeons independently examined the radiographs, and intraobserver and interobserver reliability was calculated using intraclass correlation.

RESULTS

A PUDA was present in 96% of radiographs. The average PUDA was 5.7 degrees (range, 0 degrees -14 degrees ). The Pearson correlation coefficient for a side-to-side comparison was 0.860 (P < .001). The average tip-to-apex distance was 47mm (range, 34-78mm). No correlation was identified with age. Intraobserver reliability was excellent for the PUDA and good for the tip-to-apex distance. Interobserver reliability was good for the PUDA and the tip-to-apex distance.

DISCUSSION

A mean PUDA of 5.7 degrees is present in 96% of patients at an average of 47mm distal to the olecranon tip. Measurement of the PUDA has good-to-excellent interobserver and intraobserver reliability.

CONCLUSION

Contralateral PUDA measurements are reliable in determining the angle in patients with comminution or distorted anatomy. Recognition of the PUDA may be helpful in anatomic plating of the ulna. Recognition of the PUDA may be helpful in anatomic plating of the ulna for fractures, nonunions or malunions.

LEVEL OF EVIDENCE

Radiographic study.

Distal attachment of the brachialis muscle: anatomic and MRI study in cadavers

OBJECTIVE

The purpose of this study was to use MRI and anatomic correlation in cadavers to delineate the anatomic features of the distal attachment of the brachialis muscle.

MATERIALS AND METHODS

MRI was performed on 13 cadaveric elbows. The MRI findings were compared with those in anatomic sections and histologic preparations. The brachialis muscle of one cadaver was dissected.

RESULTS

The dissected brachialis muscle had two heads, superficial and deep. The attachment of the superficial head to the ulnar tuberosity was farther distal than that of the deep head. The attachments of all aspects of the muscle included a tendinous layer rather than purely muscular structures. Histologic analysis showed no direct communication between the brachialis and biceps brachii tendons or between the brachialis tendon and joint capsule.

CONCLUSION

Familiarity with the anatomic features of the distal brachialis muscle and tendon is essential for accurate assessment of these structures.

Coronoid fractures of the elbow

Coronoid fractures of the ulna are relatively uncommon, yet critical injuries to recognize. They often occur in association with elbow dislocations and play an important role in elbow instability. Historic recommendations are to fix all large coronoid fracture fragments, as well as small fracture fragments associated with instability. There is little data regarding management of small coronoid fracture fragments. The coronoid process acts as a bony buttress to prevent posterior dislocation and has three soft tissue insertions which lend stability as well: the anterior joint capsule of the elbow, the brachialis muscle and the medial ulnar collateral ligament. Injured patients often present with swelling, tenderness and limited range of motion. After obtaining a detailed history and performing a careful physical examination, plain radiographs should be obtained. If present, dislocations are reduced and post-reduction stability is assessed. If the elbow is unstable, management usually consists of a combination of bony and soft-tissue repairs often including coronoid process repair. Loss of motion is the most common complication of these injuries. The current recommendation is to repair virtually all coronoid fractures associated with instability.