Biomechanical analysis of medial collateral ligament reconstruction grafts of the elbow

Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction Between Palmaris Longus Autograft and Knee Medial Collateral Ligament Allograft

Background

Medial ulnar collateral ligament (mUCL) injury can cause significant pain and alter throwing mechanics. Common autograft options for mUCL reconstruction (UCLR) include the palmaris longus (PL) and hamstring tendons. Allograft use may reduce donor site morbidity and decrease function related to PL autografts.

Purpose

To compare varus stability and load to failure between a novel allograft for UCLR-knee medial collateral ligament (kMCL)-and a PL autograft in human donor elbow specimens.

Study Design

Controlled laboratory study.

Methods

A total of 24 fresh-frozen human elbows were dissected to expose the mUCL. Medial elbow stability was tested with the mUCL intact (native), deficient, and reconstructed utilizing the humeral single-docking technique with either a (1) kMCL allograft (n = 12) or (2) a PL autograft (n = 12). A 3-N·m valgus torque was applied to the elbow, and valgus rotation of the ulna was recorded via motion tracking cameras. The elbow was cycled through a full range of motion 5 times. After kinematic testing, specimens were loaded to failure at 70° of elbow flexion, and failure modes were recorded.

Results

The mUCL-deficient elbows demonstrated significantly greater valgus rotation compared with the intact and reconstructed elbows at every flexion angle tested (10°-120°) (P <.001). Both kMCL- and PL-reconstructed elbows exhibited significantly higher mean valgus rotation compared with the intact state between 10° and 40° of flexion (P < .01). There were no significant differences in valgus rotation at any flexion angle between the kMCL and PL graft groups. When loaded to failure, elbows reconstructed with both kMCL and PL grafts failed at similar torque values (18.6 ± 4 and 18.1 ± 3.4 N·m, respectively; P = .765).

Conclusion

Fresh-frozen and aseptically processed kMCL allografts demonstrated similar kinematic and failure properties to PL tendon autografts in UCL-reconstructed elbows, although neither graft fully restored kinematics between 10° and 40°.

Clinical Relevance

Prepared kMCL ligament allografts may provide a viable graft material when reconstructing elbow ligaments while avoiding the potential complications related to PL autografts- including donor site morbidity.

Static stability of novel uncemented elbow hemiarthroplasty stabilized with ligament reconstruction

BACKGROUND

The purpose of this study was to create a model to simulate treatment of unreconstructable distal humerus fractures with hemiarthroplasty. Stability was restored with a latest plate-system that simultaneously tensions medial and lateral collateral ligament grafts.

MATERIALS AND METHODS

Static varus and valgus elbow stability was tested in 11 cadaver elbows with intact ligaments and capsule at 5 flexion angles (0°, 30°, 60°, 90°, 120°). The elbows were then destabilized via release of all ligaments and capsular attachments. The distal humerus articular cartilage was excised and replaced with an uncemented hemiarthroplasty. Ligament reconstruction was subsequently performed, and elbow stability was measured and compared to the native state. Dimensions of the hemiarthroplasty component were compared to native elbow dimensions to assess and quantify any existing relationship to elbow stability.

RESULTS

A hemiarthroplasty was implanted in all specimens. A size mismatch occurred between the distal humerus trochlea and the olecranon fossa in all specimens and averaged 6.3 mm. Following ligament reconstruction, specimens reproduced the flexion angle-dependent stability of native elbows to both varus and valgus stress. On the medial side, elbow joint stability in mid-flexion was approximately 7% tighter after hemiarthroplasty. Laterally, the elbow was approximately 15% tighter after hemiarthroplasty and demonstrated peak stability in full flexion. The 3 assessed hemiarthroplasty components and bony dimensions did not exhibit any relationship between implant-bone mismatch and elbow stability after ligamentous reconstruction.

CONCLUSION

Cadaveric elbow specimens underwent uncemented hemiarthroplasty with soft tissue stabilization with a novel technique for ligament reconstruction. Following hemiarthroplasty and ligament reconstruction, these specimens maintained secure fixation between ligament and bone. Static stability was maintained at varying degrees of elbow flexion regardless of variable mismatch between the hemiarthroplasty component and the native olecranon fossa.

Testing of a Novel Method for Securing Ligaments Against Bone During Simultaneous Medial and Lateral Elbow Ligament Reconstruction

PURPOSE

A ligament reconstruction method that simultaneously tensions the medial and lateral sides of the elbow and maintains tension with compression plates on the proximal ulna is proposed for the treatment of bidirectional elbow ligament instability. Graft slippage, catastrophic failure, and excessive displacement were evaluated. Biomechanical stability without graft slippage was hypothesized.

METHODS

Eight cadaveric ligament reconstruction simulations were created through the dissection of three cadaver arms. Each reconstruction was statically tested with 160 N in a manner where it was first augmented with an absorbable suture and then without. Then, 3 more ligament reconstruction simulations were created for dynamic testing with each undergoing testing at 80 N for 2,000 cycles at 2 Hz. Construct displacement and graft slippage were recorded for each load application.

RESULTS

No grafts failed catastrophically and no graft slippage was observed with either static or dynamic loading. Under static loading, the mean change in displacement between augmented and nonaugmented ligament reconstruction simulations was 28.7% ± 21% (augmented 3.95 ± 1.81 mm vs nonaugmented 4.89 ± 2.22 mm). The mean stiffness was 66.6 ± 26.6 N/mm for augmented and 64.6 ± 23.2 N/mm for nonaugmented simulations. With dynamic loading, the mean displacement for augmented graft ligament reconstruction simulations was 1.55 ± 0.16 mm compared with 2.18 ± 0.77 mm for nonaugmented reconstruction simulations.

CONCLUSIONS

This method of fixation to the proximal ulna for the simultaneous reconstruction of medial and lateral elbow ligaments successfully prevented graft slippage without excessive construct displacement during static and dynamic testing. Ligament augmentation with absorbable sutures decreased the construct displacement.

CLINICAL RELEVANCE

This ligament fixation method may be a viable alternative for the treatment of concomitant medial and lateral elbow instability.

Testing of Novel Total Elbow Prostheses Using Active Motion Experimental Setup

PURPOSE

The goal of this study was to test a novel uncemented and unconstrained total elbow arthroplasty (Kaufmann total elbow) design that is stabilized through a ligament reconstruction.

METHODS

We quantified the implant stability after 25,000 cycles, which represents the time between implantation and when ligament and bone healing has occurred. We used an active motion experimental setup that applies tendon loads via pneumatic cylinders and reproduces the forearm-originating dynamic stabilizers of the elbow. The novel total elbow arthroplasty was actuated for 5,000 full flexion-extension cycles at 5 different shoulder positions. Four Sawbones and 4 cadaver elbows were employed. Angular laxity and implant stability were recorded prior to testing and after each 5,000-loading cycle.

RESULTS

Four Sawbones and 4 cadaver elbows were implanted with the uncemented total elbow arthroplasty and did not demonstrate fixation failure or substantial laxity after 25,000 cycles of loading imparted at different shoulder positions.

CONCLUSIONS

Our findings demonstrate that the Kaufmann total elbow replacement implanted into cadaver and Sawbones specimens did not exhibit fixation failure or excessive laxity after 25,000 cycles.

CLINICAL RELEVANCE

An uncemented, nonmechanically linked total elbow arthroplasty that gains component fixation using intramedullary screws and employs a ligament reconstruction to stabilize the elbow has the potential to be a valuable management option, particularly in younger patients.

Mechanical properties and microstructural organization of common ulnar collateral ligament grafts: Palmaris longus and gracilis tendons

Ulnar collateral ligament (UCL) injuries are becoming increasingly common. The palmaris longus (PL) and gracilis (GR) tendons are the most common grafts used in UCL reconstructions. While clinical studies have demonstrated relatively similar outcomes for either graft, there is little quantitative data describing these grafts from a material perspective, specifically the mechanical and microstructural properties of these tissues and how they respond under dynamic loading. The purpose of this descriptive laboratory study was to quantify and compare the mechanical and microstructural properties of PL and GR tendons. A total of 13 PL and 11 GR cadaveric human tendons were obtained. Each specimen was divided into three subregions and subjected to preconditioning, ramp-and-hold stress-relaxation and ramp-to-failure testing. Mechanical parameters were computed for each sample, and a polarized light imaging technique was used to simultaneously evaluate dynamic microstructural properties during testing. The PL had larger toe- and linear-region modulus values than the GR. Within the GR, the distal subregion had stronger collagen alignment than the proximal subregion at the zero, transition and linear portions of the stress-strain curve. The PL and GR, have similar mechanical properties and similar microstructural alignment under load. The PL graft has similar properties throughout its length whereas the GR properties exhibited slight differences in strength of alignment along its length. The PL and GR exhibit larger moduli values and more strongly/uniformly aligned collagenous microstructure when qualitatively compared to data previously published on the native UCL.

Return-to-Sport Outcomes After Primary Ulnar Collateral Ligament Reconstruction With Palmaris Versus Hamstring Tendon Grafts: A Systematic Review

Background

Ulnar collateral ligament (UCL) reconstruction is the current gold standard of treatment for overhead athletes with a symptomatic, deficient UCL of the elbow who have failed nonoperative treatment and wish to return to sport (RTS) at a high level. The palmaris longus and hamstring tendons are common graft choices, but no study has analyzed the existing literature to assess whether one graft is superior to the other.

Purpose

To systematically report on the outcomes of UCL reconstruction using palmaris and hamstring autografts.

Study Design

Systematic review; Level of evidence, 4.

Methods

A combination of the terms "ulnar collateral ligament," "valgus instability," "Tommy John surgery," "hamstring," and "palmaris longus" were searched in PubMed, Embase, and the Cochrane Library. RTS and return-to-same-level (RSL) rates, patient-reported outcomes, and complications were included for analysis. We used the modified Coleman Methodology Score and risk-of-bias tool for nonrandomized studies to assess the quality of the included studies.

Results

This review included 6 studies (combined total of 2154 elbows) that directly compared palmaris and hamstring graft use in UCL reconstruction. Follow-up ranged from 24 to 80.4 months, and the mean patient age across all studies was 21.8 years. The mean RSL across all studies and grafts was 79.0%, and the mean RTS was 84.1%, consistent with results previously reported in the literature. The mean RTS and RSL rates for the palmaris graft group were 84.6% and 82%, respectively; the hamstring graft group showed mean RTS and RSL rates of 80.8% and 80.8%. Meta-analysis revealed no significant difference in RSL between the 2 graft groups (odds ratio, 1.06; 95% CI, 0.77-1.46). The combined complication rate of the included studies was 18.2%, with failure rates ranging from 0% to 7.1%.

Conclusion

Results of this review indicated that both palmaris and hamstring tendon grafts are viable options for primary UCL reconstruction. Graft choice should be determined by a combination of patient and surgeon preference.

Is Allograft Reconstruction of the Medial Ulnar Collateral Ligament of the Elbow a Viable Option for Nonelite Athletes? Outcomes at a Mean of 8 Years

Background:

The rate of elbow medial ulnar collateral ligament (MUCL) injury and surgery continues to rise steadily. While authors have failed to reach a consensus on the optimal graft or anchor configuration for MUCL reconstruction, the vast majority of the literature is focused on the young, elite athlete population utilizing autograft. These studies may not be as applicable for the “weekend warrior” type of patient or for young kids playing on high school leagues or recreationally without the intent or aspiration to participate at an elite level.

Purpose:

To investigate the clinical outcomes and complication rates of MUCL reconstruction utilizing only allograft sources in nonelite athletes.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patient records were retrospectively analyzed for individuals who underwent allograft MUCL reconstruction at a single institution between 2000 and 2016. A total of 25 patients met inclusion criteria as laborers or nonelite (not collegiate or professional) athletes with a minimum of 2 years of postoperative follow-up. A review of the medical records for the included patients was performed to determine survivorship free of reoperation, complications, and clinical outcomes with use of the Summary Outcome Determination (SOD) and Timmerman-Andrews scores. Statistical analysis included a Wilcoxon rank-sum test to compare continuous variables between groups with an alpha level set at .05 for significance. Subgroup analysis included comparing outcome scores based on the allograft type used.

Results:

Twenty-five patients met all inclusion and exclusion criteria. The mean time to follow-up was 91 months (range, 25-195 months), and the mean age at the time of surgery was 25 years (range, 12-65 years). There were no revision operations for recurrent instability. The mean SOD score was 9 (range, 5-10) at the most recent follow-up, and the Timmerman-Andrews scores averaged 97 (range, 80-100). Three patients underwent subsequent surgical procedures for ulnar neuropathy (n = 2) and contracture (n = 1), and 1 patient underwent surgical intervention for combined ulnar neuropathy and contracture.

Conclusion:

Allograft MUCL reconstruction in nonelite athletes demonstrates comparable functional scores with many previously reported autograft outcomes in elite athletes. These results may be informative for elbow surgeons who wish to avoid autograft morbidity in common laborers and nonelite athletes with MUCL incompetency.

Comparison of Outcomes Based on Graft Type and Tunnel Configuration for Primary Ulnar Collateral Ligament Reconstruction in Professional Baseball Pitchers

BACKGROUND

Professional baseball pitchers are at high risk for tears of the ulnar collateral ligament (UCL) of the elbow, often requiring surgical reconstruction. Despite acceptable published return-to-play outcomes, multiple techniques and graft types have been described.

PURPOSE

This study compares UCL reconstruction (UCLR) outcomes based on tunnel configuration and graft type.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

After approval from our institutional review board and Major League Baseball (MLB), 566 professional baseball pitchers who underwent UCLR between 2010 and 2014 were identified and included. The following patient characteristics were analyzed: age, pitching role (starter vs reliever), level of play (MLB vs Minor League Baseball [MiLB]), and throwing side dominance. Surgical factors analyzed included reconstruction technique, graft type, and concomitant procedures. Primary outcome measures consisted of the ability to return to play at any level (RTP), ability to return to the same level of play (RSL), time to return, subsequent elbow injuries, and need for subsequent or revision elbow surgery. The effects of patient and surgical factors on outcomes were analyzed using multivariate linear and logistic regression modeling.

RESULTS

The RTP rate was 79.9%, and the RSL rate was 71.2%. Grafts used to reconstruct the UCL included the palmaris longus autograft (n = 361, 63.7%), the gracilis autograft (n = 135, 23.8%), and other grafts (n = 70, 12.5%). Surgical techniques utilized were the docking technique (n = 171, 30.2%), the modified Jobe technique (n = 290, 51.2%), and other techniques (n = 105, 18.6%). There were no significant differences in the time to RTP or RSL based on reconstruction technique or graft type. RTP rates were similar for the docking versus modified Jobe technique (80.1% vs 82.4%, respectively; P = .537) and for the 2 primary graft types (83.1% for palmaris longus vs 80.7% for gracilis; P = .596). The rate of subsequent elbow surgery was 10.5% for the docking technique versus 14.8% for the modified Jobe technique ( P = .203), and the rate of revision UCLR was 2.9% versus 6.2% for the docking versus modified Jobe technique, respectively ( P = .128). Significant trends toward an increasing use of the palmaris longus autograft ( P = .023) and the docking technique ( P = .006) were observed. MLB pitchers were more likely than MiLB pitchers to RTP ( P < .001) and RSL ( P < .001), but they required a longer time to return (mean difference, 35 days; P = .039) and had a higher likelihood of subsequent elbow (odds ratio [OR], 3.58 [95% CI, 2.06-6.23]; P < .001) and forearm injuries (OR, 5.70 [95% CI, 1.99-16.30]; P = .004) but not subsequent elbow surgery. No specific variables correlated with the rates of subsequent elbow surgery or revision UCLR in the multivariate analysis. The use of concomitant ulnar nerve transposition did not affect outcomes.

CONCLUSION

Surgical outcomes in professional baseball players are not significantly influenced by UCLR technique or graft type. There was a high rate (46.3%) of subsequent throwing elbow injuries. MLB pitchers were more likely to RTP and RSL, but they had a higher frequency of subsequent elbow and forearm injuries than MiLB pitchers. Both the docking technique and the palmaris longus autograft are increasing in popularity among surgeons treating professional baseball players.

Surgical Reconstructions for Posterolateral Rotatory Instability of Elbow using a Synthetic Ligament

Background

Chronic posterolateral rotatory instability occurs as a result of disruption of the lateral ulnar collateral ligament of the elbow. It is usually treated by ligament reconstruction using an autogenous graft. We present our experience of reconstruction with the use of a synthetic polyester (LARS®; Ligament Advanced Reinforcement System; Surgical Implants and Devices, Arc-sur-Tille, France) ligament and discuss the advantages of this technique.

Methods

Ten consecutive cases of lateral ligament reconstruction using a LARS® ligament were reviewed. The mean age at the time of surgery was 30.2 years. The mean duration of instability symptoms preoperatively was 32.4 months. Three patients had generalized hyperlaxity. Three patients had previously undergone an unsuccessful autogenous graft reconstruction.

Results

The mean postoperative follow-up was 27 months. At review, seven of the 10 patients had stable elbows with no feelings of recurrent instability. This included two of the patients with generalized hyperlaxity. The mean postoperative arc of flexion/extension was 13° to 137°. The mean Mayo Elbow Performance Score was 87.5.

Conclusions

The use of a synthetic ligament for reconstruction of posterolateral rotatory instability of the elbow provides satisfactory stability. It avoids the associated morbidity of using an autograft, appears to be well tolerated and is particularly valuable in the treatment of complex generalized hyperlaxity problems.

The circumferential graft technique for treatment of multidirectional elbow instability: a comparative biomechanical evaluation

BACKGROUND

Ligament reconstruction with a circumferential graft represents an innovative technique for treatment of multidirectional elbow instability. This biomechanical study compared the stability of the intact elbow joint with the circumferential graft technique and the conventional technique.

METHODS

Seven fresh frozen cadaveric elbows were evaluated for stability against valgus and varus/posterolateral rotatory forces (3 Nm) over the full range of motion. Primary stability was determined for intact specimens, after sectioning of the collateral ligaments, after applying the circumferential graft technique (box-loop), and after conventional collateral ligament reconstruction. Cyclic loading (1000 cycles) was performed to assess joint stability and stiffness of the native ligaments and the tendon grafts.

RESULTS

Primary stability of both reconstruction techniques was equal to the native specimens (P = .17-.91). Sectioning of the collateral ligaments significantly increased joint instability (P < .001). The reconstruction techniques provided equal stability after 1000 cycles (P = .78). Both were inferior to the intact specimens (P = .02). Cyclic loading caused a significantly lower increase in stiffness of the native ligaments compared with the tendon grafts of either reconstruction technique (P = .001-.008). Significantly better graft stiffness was retained with the circumferential graft technique compared with conventional reconstruction (P = .04).

CONCLUSION

Neither reconstruction technique fully reproduces the biomechanical profile of the native collateral ligaments. The circumferential graft technique seems to resist cyclic loading slightly better than the conventional reconstruction technique, yet both reconstruction techniques provide comparable stability.

Optimal management of ulnar collateral ligament injury in baseball pitchers

The ulnar collateral ligament stabilizes the elbow joint from valgus stress associated with the throwing motion. During baseball pitching, this ligament is subjected to tremendous stress and injury if the force on the ulnar collateral ligament during pitching exceeds the physiological limits of the ligament. Injuries to the throwing elbow in baseball pitchers result in significant time loss and typically surgical intervention. The purpose of this paper is to provide a review of current information to sports medicine clinicians on injury epidemiology, injury mechanics, injury risk factors, injury prevention, surgical interventions, nonsurgical interventions, rehabilitation, and return to play outcomes in baseball pitchers of all levels.

Graft diameter does not influence primary stability of ulnar collateral ligament reconstruction of the elbow

BACKGROUND

Ulnar collateral ligament insufficiency may result in medial elbow pain, instability, and reduced athletic performance in throwing athletes. Several reconstruction methods have been described, but biomechanical studies suggest that in general, stability of the graft construct is inferior to the native ulnar collateral ligament. This study investigates whether a stronger graft would yield greater resistance to valgus load over the range of motion.

METHODS

Ten cadaveric elbows were mounted to a testing fixture and incremental valgus moments of 2.5, 5, and 7.5 Nm were applied with the elbow in 120°, 90°, 60°, 30° and 0° of flexion and in varying rotational forearm positions. The intact and the ulnar collateral ligament released elbow joint were compared with the docking ulnar collateral ligament reconstruction technique, using different graft sources with increasing cross-sectional areas: palmaris longus, tricpes brachii, extensor carpi radialis longus, and semitendinosus. The resulting angular displacement was evaluated and compared between graft sources and different elbow positions.

RESULTS

Compared with the intact situation, ulnar collateral ligament release resulted in a significant increase in valgus deformation over the entire range of flexion-extension motion. Ligament reconstruction using any graft source significantly restored valgus stability at 60°, 90°, and 120°, while at 0° and 30°, angular valgus deformation did not significantly differ from the ulnar collateral ligament deficient situation. There were no significant differences in angular valgus deformation between the graft sources over the range of flexion motion or forearm rotation.

CONCLUSIONS

This study did not prove that a thicker graft yielded more resistance to valgus moments when using the docking technique. Thicker grafts require larger bone tunnels, cannot be adequately tensioned, and are non-anatomic. Therefore, the palmaris longus or a triceps tendon strip are considered more appropriate for ulnar collateral ligament reconstruction.

Percutaneous lateral ulnar collateral ligament reconstruction

PURPOSE

Open surgical reconstruction of the lateral ulnar collateral ligament is the standard treatment for symptomatic posterolateral rotatory instability of the elbow. It involves dissection and retraction of the lateral elbow muscles, which have been shown to be secondary stabilizers of the lateral elbow. We introduce a new muscle-protecting technique for single-strand lateral ulnar collateral ligament reconstruction and report on the isometry and primary stability when compared with a conventional muscle-splitting procedure. It was hypothesized that percutaneous lateral ulnar collateral ligament reconstruction provided isometry over the range of motion and that stability was comparable with a conventional open procedure.

METHODS

In sixteen human cadaver arms, the intact and the lateral collateral ligament complex-deficient situation was tested. Open lateral ulnar collateral ligament reconstruction was performed using a single-strand palmaris graft with humeral and ulnar tenodesis screw fixation. Posterolateral rotational stability was compared with a new reconstruction method, which percutaneously places a single-strand palmaris graft with humeral and ulnar tenodesis screw fixation.

RESULTS

Both open and percutaneous lateral ulnar collateral ligament reconstruction provided isometry over the range of motion and restored posterolateral stability to that of the intact situation. No significant differences between open and percutaneous reconstruction were found.

CONCLUSIONS

Percutaneous lateral ulnar collateral ligament reconstruction aims to preserve the lateral elbow muscles and to minimize soft tissue dissection. It has been shown that in an in vitro setup, this new procedure provides isometry over the range of motion and sufficiently restores posterolateral rotatory stability.

Assessment of the presence/absence of the palmaris longus muscle in different sports, and elite and non-elite sport populations

OBJECTIVES

To investigate whether higher presence of the palmaris longus muscle is associated with sports that require hand grip.

DESIGN

Cross-sectional study.

PARTICIPANTS

Six hundred and forty-two medical students, members of sports clubs and national athletes.

METHODS

Participants were invited to complete a questionnaire that assessed their main sport, elite or non-elite level of participation, and level of activity. The presence of the palmaris longus was assessed visually using a standardised test.

MAIN OUTCOME MEASURES

Presence of the palmaris longus, type of hand grip required for the sport and the level of participation.

RESULTS

The presence of the palmaris longus was higher in elite athletes (21/22, 96%) than non-elite athletes (66/84, 79%; P=0.066) for sports that require a dominant-handed or two-handed cylindrical grip (18/22, 82% and 19/35, 54%, respectively; P=0.034). For both elite and non-elite athletes, the presence of the palmaris longus was higher in those participating in sustained grip sports (325/387, 84%) compared with sports that do not require a sustained grip (150/197, 76%; P=0.012).

CONCLUSIONS

The palmaris longus may provide an advantage in certain types of sport that require hand grip, and for elite athletes participating in sports that require a dominant-handed or two-handed cylindrical hand grip. Orthopaedic specialists considering the use of the palmaris longus for a grafting procedure on an athlete should consider the level of participation and the type of hand grip required in the athlete's sport.