Coronoid reconstruction using osteochondral grafts: a biomechanical study

Acute and chronic coronoid reconstruction using the olecranon Tip

Post-traumatic coronoid deficiency in the elbow can lead to chronic pain, instability and arthritis. A variety of osteochondral grafts have been used to reconstruct the coronoid, and restore elbow stability. The radial head and iliac crest grafts are the most common in the literature but have limitations. The olecranon tip is a promising alternative, with both cadaveric and computer models demonstrating superior congruency, without compromising elbow stability or disrupting the extensor mechanism. We present a small, case series demonstrating the technique for contralateral and ipsilateral grafts in both the acute and chronic setting.

Improved Understanding of Traumatic Complex Elbow Instability

Recent advancements in surgical treatment have improved clinical results in complex traumatic elbow injury. There is increasing recognition that conservative treatment and inadequate surgical fixation carry high risk of substantial morbidity in many of these cases. Recent literature displays improved outcomes in complex elbow instability, in part, because of a more complete comprehension of the injury patterns and fixation methods. Prompt surgical management with stable internal fixation, which permits immediate postoperative mobilization, has been a consistent variable across the reports leading to more satisfactory outcomes. This applies to both acute and chronic cases.

[Elbow joint dislocation : Frequent concomitant injuries and current treatment concepts]

Dislocations of the elbow joint are among the most prevalent dislocation injuries in the human body after shoulder joint dislocations and represent a challenge in the clinical routine because of the concomitant injuries and complications. They predominantly affect young adults who become injured during athletic or daily activities. A distinction is generally made between a simple elbow dislocation and a dislocation fracture of the elbow; however, a uniform classification or treatment algorithm has not yet been established, especially for simple elbow dislocations with associated ligamentous, muscular and capsular concomitant injuries. Due to this and the complexity of this injury, a standardized approach is needed to initiate the optimal treatment at an early stage and to correctly select the narrow treatment pathway between impending chronic instability and elbow stiffness.

Biomechanical impact of elbow motion in elbow stiffness

BACKGROUND

A mechanical block in the elbow due to osteophytes in the olecranon fossa is a common clinical symptom for elbow stiffness.

PURPOSE/HYPOTHESIS

This study aims to understand the biomechanical characteristics or changes in the stiff elbow in the resting (or neutral) and swing position of the arm using a cadaveric model. The hypotheses included the following: (1) a difference exists in the articular contact pressure of the elbow by comparing the non-stiff and stiff models in in vivo studies; (2) the degree of stiffness would affect the increase of the joint loading of the elbow.

STUDY DESIGN

Controlled laboratory study, cadaveric study.

METHODS

Eight fresh-frozen specimens from individuals of both sexes were included in the biomechanical study. The specimen was mounted on a custom-designed jig system with gravity-assisted muscle contracture to mimic the elbow in a standing position. The elbow was tested in two conditions (the resting and passive swing). Contact pressure was recorded for three seconds in the resting position, which was the neutral position of the humerus. By dropping the forearm from 90° of the elbow flexion, the passive swing was performed. The specimens were tested sequentially in three stages of stiffness (stage 0, no stiffness; stage 1, 30° of extension limitation; and stage 2, 60° of extension limitation). After data collection was completed in stage 0, a stiff model was sequentially created for each stage. The stiff model of the elbow was created by blocking the olecranon by inserting a 2.0 K-wire into the olecranon fossa horizontally with the intercondylar axis.

RESULTS

The mean contact pressures were 279 ± 23, 302 ± 6, and 349 ± 23 kPa in stages 0, 1, and 2, respectively. The increases in the mean contact pressure in stages 2 versus 0 were significant (P < 0.0001). The mean contact pressures were 297 ± 19, 310 ± 14, and 326 ± 13 kPa in stages 0, 1, and 2, respectively. The peak contact pressures were 420 ± 54, 448 ± 84, and 500 ± 67 kPa in stages 0, 1, and 2, respectively. The increases in mean contact pressure in stage 2 versus 0 were significant (P = 0.039). The increases in peak contact pressure in stages 0 versus 2 were significant (P = 0.007).

CONCLUSIONS

The elbow bears the load created by gravity and muscle contracture in the resting and swing motion. Moreover, extension limitation of stiff elbow increases the load bearing in the resting position and swing motion. Careful surgical management should be considered for meticulous clearance of bony spur around olecranon fossa to resolve the extension limitation of the elbow.

The role of the lateral part of the distal triceps and the anconeus in varus stability of the elbow: a biomechanical study

BACKGROUND

The role of the lateral part of the distal triceps as a stabilizer in the lateral collateral ligament-deficient elbow and whether its effect in improving the stability is independent of that of the anconeus are unclear.

METHODS

Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. An injury model was created by sectioning the lateral collateral ligament and sparing the common extensor origin. The lateral part of the distal triceps tendon was loaded sequentially with 0 N, 10 N, 25 N, and 40 N. Each stage of the lateral part of the distal triceps loading was tested with the anconeus unloaded (inactive) or with a 25-N load applied (active). Articular contact pressures on the coronoid, the medial facet, and the lateral facet were collected and processed using Tekscan sensors and software.

RESULTS

A significant decrease in the mean coronoid contact pressure was seen with sequential loading of the lateral part of the distal triceps (P < .001). The ratio of medial to lateral facet contact pressures significantly decreased with sequential loading of the lateral part of the distal triceps (P < .001), indicating a better distribution of the contact pressure between the medial and lateral facets as the lateral part of the distal triceps was loaded. These effects were statistically significant, both with and without anconeus loading. There was no significant modification of the effect of the lateral part of the distal triceps loading on the contact pressure by the anconeus loading (P = .47). However, with active anconeus loading, the contact pressure and the ratio of medial to lateral facet contact pressures were significantly lower for any stage of lateral triceps loading (P < .001), indicating a synergistic effect of the anconeus.

CONCLUSIONS

In a lateral collateral ligament-deficient elbow, the lateral part of the distal triceps loading prevents the increased contact pressure on the coronoid under varus stress and improves the distribution of contact pressures on the coronoid. Anconeus loading further decreases and improves the distribution of the contact pressures; however, its effect is independent of that of the lateral part of the distal triceps. These results substantiate a role of the lateral part of the distal triceps as a dynamic constraint against elbow varus and have clinical implications for prevention and rehabilitation of elbow instability.

The role of the lateral collateral ligament-capsule complex of the elbow under gravity varus

BACKGROUND

The lateral collateral ligament complex along with the capsule is likely to be at risk during arthroscopic extensor carpi radialis brevis release for lateral epicondylitis. We hypothesized that disruption of the lateral collateral ligament-capsule complex (LCL-cc) would increase the mean contact pressure on the coronoid under gravity varus.

MATERIALS AND METHODS

Eight cadaveric elbows were tested via gravity varus and weighted varus (2 Nm) stress tests using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. Mean articular surface contact pressure data were collected and processed using intra-articular thin-film sensors and software. Sequential testing was performed on each specimen from stage 0 to stage 3 (stage 0, intact; stage 1, release of anterior one-third of LCL-cc; stage 2; release of anterior two-thirds of LCL-cc; and stage 3, release of entire LCL-cc). The mean contact pressure on the coronoid and the mean ratio of contact pressure on the medial coronoid to that on the lateral coronoid (M/L ratio) were used for comparisons among the stages and the intact elbow.

RESULTS

The overall mean contact pressure significantly increased in stage 2 (P = .0004 in gravity varus and P = .0001 in weighted varus) and stage 3 (P < .0001 in gravity varus and P < .0001 in weighted varus) compared with that in stage 0. In contrast, release of the anterior one-third of the LCL-cc (stage 1) did not significantly increase the mean contact pressure on the coronoid in any degree of flexion under gravity varus (P = .09) or weighted varus loading (P = .6). The M/L ratio difference between stage 0 and stage 1 was 1.1 ± 1.1 under gravity varus (P = .8) and 2.1 ± 1.0 under weighted varus (P = .2). The overall M/L ratios in stage 2 and stage 3 were significantly higher than those seen in stage 0 under gravity varus (P = .04 in stage 2 and P = .02 in stage 3) and weighted varus (P = .006 in stage 2 and P < .0001 in stage 3).

CONCLUSIONS

Loss of the anterior two-thirds or more of the LCL-cc significantly increases the overall mean contact pressure on the coronoid, especially the medial coronoid, under both gravity varus and weighted varus. The LCL-cc also plays a role in the distribution of coronoid contact pressure against gravity varus loads.

Effect of Radiocapitellar Joint Over/Under Stuffing on Elbow Joint Contact Pressure

PURPOSE

Comminuted radial head fractures are commonly treated by surgical resection or replacement with a prosthesis. A potential problem with radial head replacement is overlengthening of the radial neck ("overstuffing" of the radial head), which has been shown to affect both ulnohumeral kinematics and radiocapitellar pressures. We hypothesized that an overstuffed radial head prosthesis increases capitellar pressure and reduces coronoid pressure.

METHODS

Seven human cadaveric elbows were prepared on a custom-designed apparatus simulating stabilizing muscle loads, and passively flexed from 0° to 90° under gravity valgus torque while joint contact pressures were measured. Each elbow was tested sequentially with different neck lengths, starting with the intact specimen followed by insertion of understuffed (-2 mm), standard-height (0 mm), and overstuffed (+2 mm) radial head prostheses in neutral forearm rotation, 40° pronation, and 40° supination positions, respectively.

RESULTS

Capitellar mean contact pressures significantly increased after insertion of an overstuffed radial head prosthesis. In valgus position with neutral forearm rotation, capitellar mean contact pressure on the joint with an intact radial head averaged 227 ± 70 kPa. Insertion of understuffed, standard-height, and overstuffed radial head prostheses changed the mean contact pressures to 152 ± 76 kPa, 212 ± 68 kPa, and 491 ± 168 kPa, respectively. The overstuffed radial head group had significantly lower whole coronoid mean contact pressures (153 ± 56 kPa) compared with the intact (390 ± 138 kPa) and standard-height (376 ± 191 kPa) radial head groups.

CONCLUSIONS

An increase in radial prosthesis height significantly increases capitellar contact pressures and reduces coronoid contact pressures.

CLINICAL RELEVANCE

Restoration of the anatomic radial head height is critical when performing radial head arthroplasty to maintain normal joint biomechanics. Elevated capitellar contact pressures can potentially lead to pain and early degenerative changes.

A Novel Suture-Preset Spring Plate System (SSPS) for Comminuted Coronoid Process Fracture in the Elbow

OBJECTIVE

This study is aimed to investigate the clinical outcomes of a novel SSPS for fixation of the comminuted coronoid fracture.

METHODS

A retrospective study was carried out in the patients with comminuted fractures of the coronoid treated by SPSS fixation between January 2014 and December 2018. A total of 17 patients (17 sides) was included in our study, including 11 male and six female, with a mean age range from 18 to 60. All cases started to functional rehabilitation immediately after the operation. Clinical outcomes were evaluated both radiographically and functionally at the follow-up visit, including the elbow instability, range of motion and Mayo elbow performance score (MEPS).

RESULTS

According to the O'Driscoll classification system, there was two side of type 1.2, two of type 2.1, four of type 2.2, three of type 2.3, two of 3.1 and four of type 3.2. The surgery was carried out by Kocher and anteromedial approach in 12 patients, posterior and anteromedial approach in four, anterior approach in one. The average operation time and intraoperative blood loss was 129.41±43.87 min and 115.29±104.65 ml. The median follow-up time was 9 months (range, 6 to 15 months). The mean flexion, extension, pronation and supination motion was 138.76±8.67 degrees, 20.00±13.58, 82.94±5.32and 74.12±14.39 respectively at final follow up. The mean MEPS score was 89.76±8.46, including 11 excellent, 3 good and 3 fair result. The mean VAS score was 1.94±0.97. The mean union time of coronoid fractures was 2.77±0.31 months according to the established standard of healing. There were no significant differences in clinical outcomes among groups according to the O'Driscoll classification (P > .05) and ligament repair strategy (P > .05). No patient underwent instability or dislocation of the elbow during follow up. There were two cases with mild ulnar nerve symptoms which recovered totally at follow up. Meanwhile, there were three cases with heterotopic ossification of the elbow.

CONCLUSION

Our findings demonstrated that the SSPS can provide a reliable fixation for the comminuted coronoid fracture with satisfactory clinical outcomes.

[Coronoid reconstruction with autologous iliac crest bone graft in chronic elbow instability through a medial approach]

OBJECTIVE

Neutralizing a posteromedial rotatory instability (PMRI) caused by coronoid deficiency by restoration of the humeroulnar joint surface with an autologous iliac crest bone graft.

INDICATIONS

Surgery is indicated in patients with chronic deficiency of the anteromedial facet of the coronoid with subsequent PMRI.

CONTRAINDICATIONS

Coronoid reconstruction is not recommended in patients with advanced osteoarthritis of the elbow caused by subluxation of the humeroulnar joint. General contraindications like acute infection, pregnancy and lack of operability should also be taken into account.

SURGICAL TECHNIQUE

First, a medial approach is established and the base of the coronoid is prepared. Afterwards an autologous iliac crest bone graft is placed onto the defect and secured by screws or a plate. In addition, a reconstruction of the anterior bundle of the medial collateral ligament with an autologous tendon graft is performed.

POSTOPERATIVE MANAGEMENT

An elbow orthesis is worn for 6 weeks after surgery to avoid valgus or varus stress. There is no restriction in range of motion. A continuous passive motion elbow chair supports the patient in regaining elbow mobility.

RESULTS

Between 2015 and 2017, we treated 10 patients suffering from chronic coronoid defects with coronoid reconstruction. Eight of the patients were available for follow-up 86 weeks after surgery. The mean age was 41.4 years. In all patients, elbow range of motion and patient-related outcome measures were improved after surgery. Plain radiographs illustrated correct centering of the elbow joint. One patient had to undergo elbow arthroplasty and was excluded. Coronoid reconstruction with an autologous iliac crest bone graft restored humeroulnar joint congruency and improved satisfaction in patients suffering from chronic coronoid deficiency.

Effect of incremental increase in radial neck height on coronoid and capitellar contact pressures

BACKGROUND

Over-lengthening of the radial neck has been shown to affect ulnohumeral kinematics and has been proposed to affect radiocapitellar pressures. We hypothesized that an incremental increase in radial neck height increases the capitellar contact pressure and reduces the coronoid contact pressure. Knowledge of the effects of over-lengthening is clinically important in preventing pain and degenerative changes due to overstuffing.

METHODS

Six human cadaveric elbows were prepared on a custom-designed apparatus simulating muscle loads and passive flexion from 0° to 90° under gravity valgus torque while measuring joint contact pressures in this biomechanical study. Each elbow was tested sequentially starting with the intact specimen followed by insertion of a radial head prosthesis with 0, +2, and +4 mm of radial neck height, respectively.

RESULTS

Capitellar mean contact pressures significantly increased after insertion of +2 and +4 mm radial head prostheses (p < 0.03). The capitellar mean contact pressure with a 0 mm radial head prosthesis was 97 KPa. Insertion of +2 mm and +4 mm radial heads increased mean contact pressures to 391 KPa (p = 0.001) and 619 KPa (p = 0.001), respectively, with 90° of elbow flexion.

DISCUSSION

Increasing radial prosthesis height by 2 mm significantly increases capitellar contact pressures and reduces coronoid contact pressures.

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.

Management of the Posttraumatic Coronoid-Deficient Elbow

Posttraumatic coronoid deficiency is one of the most challenging scenarios even for the most experienced elbow surgeon. Surgical options can be grouped into soft tissue reconstructions, autogenous corticocancellous bone graft reconstructions, osteochondral reconstructions, and prosthetic replacement. However, the literature is inconclusive with limited cases, short follow-up, and no conclusive clinical comparative studies of these techniques. This article provides a review of the current surgical options, and we offer the senior author's (S.W.O.) perspective after years of experience with many of these techniques.

Posteromedial rotatory incongruity of the elbow: a computational kinematics study

BACKGROUND

Our objective was to analyze the effect of different anteromedial coronoid fracture patterns with different combinations of ligamentous repairs. We hypothesized that smaller fractures would be sufficiently treated with ligamentous repair alone but that larger fragments would require a combination of ligament and bony repair versus reconstruction.

METHODS

Two multibody models were created from cadaveric specimens in the ADAMS program. Four different conditions were simulated: (1) no fracture, (2) O'Driscoll anteromedial subtype I (2.5-mm) fracture, (3) subtype II 2.5-mm fracture, and (4) subtype II 5-mm fracture. In each of these conditions, 3 ligament repairs were studied: lateral ulnar collateral ligament (LUCL), posterior bundle of the medial collateral ligament (pMCL), and both LUCL and pMCL. For each condition, kinematics and articular contact areas were calculated.

RESULTS

LUCL repair alone increases whereas pMCL repair decreases internal rotation of the ulna relative to all tested posteromedial rotatory instability conditions; their rotational effects are summative when both ligaments are repaired. With a subtype I fracture and both pMCL and LUCL injuries, repairing the LUCL alone corrects angulation whereas rotational stability is satisfactory through the arc from 0° to 90°. In a subtype II 2.5-mm fracture, isolated repair of the LUCL or pMCL is not capable of restoring rotation or angulation. For a subtype II 5-mm fracture, no combination of ligamentous repairs could restore rotation or angulation.

CONCLUSIONS

This study suggests that LUCL repair alone is sufficient to restore kinematics for small subtype I fractures for an arc avoiding deep flexion; whereas nearly normal kinematics throughout the arc of motion can be achieved if the pMCL is also repaired. Larger anteromedial coronoid fractures should ideally have fragments fixed in addition to ligament repairs.

Effect of radiocapitellar Achilles disc arthroplasty on coronoid and capitellar contact pressures after radial head excision

BACKGROUND

Long-term radiographic arthritis has been commonly reported after radial head excision. Concern over radial head arthroplasty may arise in certain situations including capitellar arthritis, radiocapitellar malalignment, and in young and active patients. We hypothesized that radial head excision increases coronoid contact pressures, which may at least be partially reduced by radiocapitellar Achilles tendon disc arthroplasty.

METHODS

Coronoid and capitellar contact pressure was measured on 6 human cadaveric elbows on a custom-designed gravity-valgus simulator under passive flexion from 0° to 90°. Sequential testing, starting with the intact specimen, resection of the radial head, and finally, radiocapitellar Achilles tendon disc arthroplasty were performed on each specimen.

RESULTS

Mean contact pressure of the coronoid significantly increased after radial head excision (P < .0001) and significantly improved after Achilles disc arthroplasty (P < .0001). The pressure difference was most pronounced on the lateral coronoid. From 15° to 85° of elbow flexion, mean contact pressures on the lateral coronoid were 291 kPa and 476 kPa before and after radial head excision, respectively (P < .0001). Achilles disc arthroplasty significantly lowered coronoid contact pressures to 385 kPa (P = .002); however, they remained significantly higher than those in the intact radial head group (P = .0009).

CONCLUSIONS

Radial head resection increases contact pressure in the coronoid, especially the lateral coronoid. This study showed that radiocapitellar Achilles disc arthroplasty significantly improves contact pressures on the coronoid after radial head resection. Achilles disc arthroplasty could be considered in patients who are not candidates for radial head arthroplasty.

The role of the posterior bundle of the medial collateral ligament in posteromedial rotatory instability of the elbow

Aims

The aim of this study was to evaluate two hypotheses. First, that disruption of posterior bundle of the medial collateral ligament (PMCL) has to occur for the elbow to subluxate in cases of posteromedial rotatory instability (PMRI) and second, that ulnohumeral contact pressures increase after disruption of the PMCL.

Materials and Methods

Six human cadaveric elbows were prepared on a custom-designed apparatus which allowed muscle loading and passive elbow motion under gravitational varus. Joint contact pressures were measured sequentially in the intact elbow (INTACT), followed by an anteromedial subtype two coronoid fracture (COR), a lateral collateral ligament (LCL) tear (COR + LCL), and a PMCL tear (COR + LCL + PMCL).

Results

There was no subluxation or joint incongruity in the INTACT, COR, and COR + LCL specimens. All specimens in the COR + LCL + PMCL group subluxated under gravity-varus loads. The mean articular contact pressure of the COR + LCL group was significantly higher than those in the INTACT and the COR groups. The mean articular contact pressure of the COR + LCL + PMCL group was significantly higher than that of the INTACT group, but not higher than that of the COR + LCL group.

Conclusion

In the presence of an anteromedial fracture and disruption of the LCL, the posterior bundle of the MCL has to be disrupted for gross subluxation of the elbow to occur. However, elevated joint contact pressures are seen after an anteromedial fracture and LCL disruption even in the absence of such subluxation. Cite this article: Bone Joint J 2018;100-B:1060–5.