Role of the lateral collateral ligament in posteromedial rotatory instability of the elbow (original) (raw)
2017, Journal of Shoulder and Elbow Surgery
Background: Posteromedial rotatory instability (PMRI) of the elbow consists of an anteromedial coronoid fracture with lateral collateral ligament (LCL) and posterior bundle of the medial collateral ligament (PMCL) tears. We hypothesized that the LCL tear is required for elbow subluxation/joint incongruity and that an elbow affected by an anteromedial subtype 2 coronoid fracture and a PMCL tear exhibits contact pressures different from both an intact elbow and an elbow affected by PMRI. Materials and methods: Six cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and to passively flex the elbow from 0°to 90°and measure joint contact pressures. After testing of the intact specimen (INTACT-elbow), an anteromedial subtype 2 coronoid fracture with a PMCL tear (COR+PMCL-elbow) and a PMRI injury (PMRI-elbow), after adding an LCL tear, were tested. The highest values of mean contact pressure were used for the comparison among the 3 groups. Results: Neither subluxation nor joint incongruity was observed in the COR+PMCL-elbow. The addition of an LCL detachment consistently caused subluxation and joint incongruity. Mean contact pressures were higher in the COR+PMCL-elbow compared with the INTACT-elbow (P < .03) but lower than in the PMRI-elbow (P < .001). Conclusions: The LCL lesion in PMRI is necessary for elbow subluxation and causes marked elevations in contact pressures. Even without subluxation, the COR+PMCL-elbow showed higher contact pressures compared with the INTACT-elbow. Treatment of PMRI should be directed toward prevention of joint incongruity, whether by surgical or nonsurgical means, to prevent high articular contact pressures.
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Articular Contact Area and Pressure in Posteromedial Rotatory Instability of the Elbow
Journal of Bone and Joint Surgery, American Volume, 2018
Background: Joint incongruity in posteromedial rotatory instability (PMRI) has been theorized to determine early articular degenerative changes. Our hypothesis was that the articular contact area and contact pressure differ significantly between an intact elbow and an elbow affected by PMRI. Methods: Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and allow passive elbow flexion (0°to 90°). The mean contact area and contact pressure data were collected and processed using the Tekscan sensor and software. After testing the intact specimen (intact elbow), a PMRI injury was simulated (PMRI elbow) and the specimen was tested again. Results: The PMRI elbows were characterized by initial joint subluxation and significantly elevated articular contact pressure. Both worsened, corresponding with a reduction in contact area, as the elbow was flexed from 0°until the joint subluxation and incongruity spontaneously reduced (at a mean [and standard error] of 60°± 5°of flexion), at which point the mean contact pressure decreased from 870 ± 50 kPa (pre-reduction) to 440 ± 40 kPa (post-reduction) (p < 0.001) and the mean contact area increased from 80 ± 8 mm 2 to 150 ± 58 mm 2 (p < 0.001). This reduction of the subluxation was also followed by a shift of the contact area from the coronoid fracture edge toward the lower portion of the coronoid. At the flexion angle at which the PMRI elbows reduced, both the contact area and the contact pressure of the intact elbows differed significantly from those of the PMRI elbows, both before and after the elbow reduction (p < 0.001). Conclusions: The reduction in contact area and increased contact pressures due to joint subluxation and incongruity could explain the progressive arthritis seen in some elbows affected by PMRI. Clinical Relevance: This biomechanical study suggests that the early degenerative changes associated with PMRI reported in the literature could be subsequent to joint incongruity and an increase in contact pressure between the coronoid fracture surface and the trochlea.
Journal of Shoulder and Elbow Surgery, 2011
Hypothesis: Complete ulnar collateral ligament (UCL) injury increases articular pressure and reduces contact area compared with the normal intact UCL. UCL reconstruction restores the contact area and contact pressure observed in the native joint. Materials and methods: Six male cadaveric elbows were mounted on a custom jig capable of simulating the 2 critical phases of the throwing motion during pitching. A contact sensor was placed through an anterior arthrotomy into the radiocapitellar joint. Each specimen then underwent valgus loading at 1.75 and 5.25 Nm of torque with the biceps, brachialis, and triceps under axial load in each testing condition. Results: The average valgus laxity in the intact elbow at 90 was 3.7 AE 0.6 at the 5.25 Nm level of torque, which doubled after transection. The reconstruction group demonstrated less laxity (2.4 AE 0.4 ) and reduced valgus angulation of the ulna at 5.25 Nm of torque. The transected UCL condition showed peak contact pressure 67% higher compared with the native ligament group at 5.25 Nm of torque. The reconstructed group increased peak articular cartilage pressures by 33% from the native ligament. At 5.25 Nm of torque for the 90 flexion phase, the transected UCL condition showed an average contact pressure of 84% greater than that of the native ligament group. Reconstruction of the UCL restored average articular pressures to within 20% of intact values at 90 .
PLRI: posterolateral rotatory instability of the elbow
Clinics in Sports Medicine, 2004
Posterolateral rotatory instability (PLRI) of the elbow is the term coined to describe the condition in which the proximal ulna and radial head externally rotate about the distal humerus when the forearm is positioned in supination and slight flexion. This pattern of ligamentous instability, which has been recently described, results from insufficiency of both the static ligamentous stabilizers and the dynamic stabilizers about the posterolateral elbow. The principal static stabilizing component is the lateral ulnar collateral ligament (LUCL), which originates at the lateral epicondyle and extends to the crest of the proximal ulna. LUCL insufficiency permits the proximal ulna and radial head to rotate externally and posterior to the distal humerus. PLRI has been portrayed in recent studies as existing on a continuum from subtle laxity to recurrent elbow dislocation. For patients whose instability symptoms persist despite appropriate conservative measures, repair or reconstruction of the lateral ligament complex may provide significant relief and functional improvement. In this article, the authors reiterate the history and salient clinical features that accompany posterolateral rotatory instability of the elbow and the definitive surgical technique for treatment of this condition [1]. History The term posterolateral instability of the elbow (PLRI) was introduced by O'Driscoll et al in a 1991 report [2] that describes 5 patients with persistent recurrent instability of the elbow. Preceding this report by O'Driscoll, however, there were several reports in the literature describing similar elbow pathology. In
EFORT Open Reviews
Chronic posterolateral rotatory instability (PLRI) is the most common form of chronic elbow instability. PLRI usually occurs from a fall on the outstretched hand. On impact, the radial head and ulna rotate externally coupled with valgus displacement of the forearm. This leads to posterior displacement of the radial head relative to the capitellum, thus causing disruption of some or all of the lateral-sided stabilisers. PLRI is mainly a clinical diagnosis with a history of instability, clicking and lateral-sided pain, with a positive clinical examination including the pivot-shift test, push-up, chair and tabletop test. MRI can often help guide diagnosis but more commonly assists in surgical planning. Surgery is indicated in patients with persistent, symptomatic instability of the elbow causing pain or functional deficit. There are several surgical techniques to treat PLRI, often leading to good to excellent results. An open or arthroscopic technique has been successfully used in pati...
Management of complex elbow instability
MUSCULOSKELETAL SURGERY, 2010
Complex elbow instability is a challenging injury even for expert elbow surgeons. The preoperative radiographs should be carefully evaluated to recognize all lesions that may occur in complex elbow instabilities. Recognizing all the possible lesions is critical to achieve an optimal outcome. The most common types of injuries are as follows: (1) radial head fractures associated with lateral and medial collateral ligaments lesions (with or without elbow dislocation); (2) Coronoid fractures and lateral collateral ligament lesion (with or without elbow dislocation);
MUSCULOSKELETAL SURGERY, 2016
Background In the recent years, considerable improvements have come in biomechanical knowledge about the role of elbow stabilizers. In particular, the complex interactions among the different stabilizers when injured at the same time have been better understood. Anyway, uncertainties about both nomenclature and classification still exist in the definition of the different patterns of instability. Material and methods The authors examine the literature of the last 130 years about elbow instability classification, analyzing the intuitions and the value of each of them. However, because of the lack of a satisfactory classification, in 2015 a working group has been created inside SICSeG (Italian Society of Shoulder and Elbow Surgery) with the aim of defining an exhaustive classification as simple, complete and reproducible as possible. Results A new all-inclusive elbow instability classification is proposed. This classification considers two main parameters: timing (acute and chronic forms) and involved stabilizers (simple and complex forms), and four secondary parameters: etiology (traumatic, rheumatic, congenital…), the involved joint (radius and ulna as a single unit articulating with the humerus or the proximal radio-ulnar joint), the degree of displacement (dislocation or subluxation) and the mechanism of instability or dislocation (PLRI, PMRI, direct axial loading, pure varus or valgus stress). Conclusions This classification is at the same time complete enough to include all the instability patterns and practical enough to be effectively used in the clinical practice. This classification can help in defining a shared language, can improve our understanding of the disorder, reduce misunderstanding of diagnosis and improve comparison among different case series.
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