Humeral Trochlea Research Articles

In-vivo biomechanical analysis of osteochondritis dissecans of the humeral trochlea

Osteochondritis dissecans (OCD) of the humeral trochlea can occur among adolescent gymnasts or throwing athletes. However, the natural history and treatment strategy remain unclear because of its low incidence. The aim of this report was to determine the biomechanical influence of trochlear OCD on the elbow joint by analyzing three-dimensional in-vivo joint biomechanics in a trochlear OCD case.

Locked Elbow Joint Due to a Cartilage Flap Caused by Osteonecrosis of the Humeral Trochlea: A Case Report.

Although osteonecrosis of the humeral trochlea is a well-known complication of supracondylar humeral fractures in childhood, its frequency is relatively rare1. We report a case of a young boy with a locked elbow joint due to a cartilage flap caused by osteonecrosis of the humeral trochlea. Osteonecrosis was confirmed by follow-up radiographic examinations. The patient’s mother was informed that data concerning the case would be submitted for publication, and she provided consent. A ten-year-old boy was referred to our hospital with the symptom of locking during left elbow extension, which was accompanied with pain. The locking occurred suddenly when he turned a doorknob with the left hand. The medical history included a left supracondylar humeral fracture when he was five years old, which was treated conservatively by a local physician (Fig. 1). Fig. 1 Nondisplaced supracondylar fracture of the left elbow (arrow) when the patient was five years old. On the initial examination, no swelling or tenderness was observed in the left elbow. Although the active elbow flexion range was up to 137°, the active and passive extension loss was 75°, with painful locking. Passive extension induced pain on the posterolateral side of the lateral humeral condyle. The range of forearm motion was 90° for pronation and 80° for supination without limitation. Radiographs revealed an irregularly contoured ossification of the epiphysis in the lateral humeral condyle (Fig. 2-A), and computed tomography (CT) revealed irregular ossification of the medial trochlea (Fig. 2-B). Magnetic resonance imaging (MRI) revealed an abnormal low-intensity shadow on the T2-weighted …

Median Nerve Decompression at Lacertus Tunnel: Possible Complications

To the Editor, HAND In an interesting study by Hagert [2], the author reported the diagnosis and surgical treatment of proximal median nerve (MN) entrapment within lacertus tunnel (LT) in 44 patients. The author defined LT as the space roofed by lacertus fibrosis (LF), floored by medial humeral trochlea, bounded by pronator teres (PT) medially, and brachialis laterally. Surgical decompression of MN within LT included subcutaneous infiltration covering the area of LF and the medial/central aspect of the elbow and forearm, incision at the elbow crease of cubital fossa followed by removal of PT fascia, division of LF, and exposure of MN after medial retraction of PT [2]. However, the presence of anomalous arteries at the area of LT as shown in Fig. 1 may complicate the surgical treatment of MN compression within LT or what is called lacertus tunnel syndrome (LTS). During the dissection of cubital fossae in 75 cadavers, we found bilateral superficial brachial artery (SBA) in an old male (Fig. 1). This artery (grasped by forceps in Fig. 1) was deep to the biceptal aponeurosis or LF and very close to the median cubital vein (MCV). The SBA divided into terminal divisions; radial artery laterally and persistent median artery (PMA) medially, just above the level of medial humeral epicondyle. Both the radial artery and PMA passed ventral to the PT, where PMA accompanied the MN distally within the carpal tunnel joining the superficial palmar arch (data not shown). As shown in Fig. 1, there is a possibility of injury of the PMA which is very close to the PT fascia and subsequently could be injured on removal of this fascia during surgical decompression of MN for LTS [2]. Accordingly, injury of PMA may be serious, as this artery may contribute significantly to blood supply of the hand as in the current case [3]. On the other hand, the pressure by PMA on the MN within the elbow and carpal tunnel my complicate the symptoms of LTS which may result from double crush lesions [1]. Moreover, as shown in Fig. 1, the PMA may be injured during infiltration anesthesia for treatment of LTS, or even this artery may be injected with drugs used for infiltration anesthesia resulting in serious complications [2]. The PMA may be also injured during surgical treatment of PT syndrome [3]. Compressive effects of the LF have been described as causing dysfunction of the musculocutaneous nerve and brachial artery [4]; and in the current case, there is a possibility of compression of the PMA by LF. Fig. 1 Superficial arteries at the elbow. The framed area shows the boundaries and contents of lacertus tunnel (LT). SBA superficial brachial artery, PMA persistent median artery, RA radial artery, UA ulnar artery, LF lacertus fibrosis, and PT pronator teres. ... As Hagert [2] illustrated a diagram showing boundaries and contents of LT, we think that the SBA and PMA could be possible contents of LT with surgical relevance. Moreover, the MCV could be added to the roof of LT based on clinical impotence [5]

Coronal Shear Fracture of the Humeral Trochlea

To review records of 5 patients with anterior coronal trochlear fractures. Four men and one woman aged 25 to 46 (mean, 34) years underwent cancellous screw (n=3) or Kirschner wire (n=2) fixation for anterior coronal fractures of the humeral trochlea after falling on a flexed elbow. Patients were operated on through a medial approach. Three patients who had a large osteochondral fragment underwent fixation using 4-mm AO partially threaded cancellous screws. Two patients who had a small un-amenable osteochondral fragment (with articular cartilage damage) underwent fixation using Kirschner wires. Patients were evaluated using the Mayo Elbow Performance Index (MEPI) based on pain, arc of motion, stability, and functional disability. The mean time from injury to surgery was 7 (range, 5-10) days. The mean follow-up period was 2.7 years. No patient had any wound-related problems, postoperative neurovascular compromise, or avascular necrosis. Radiographic union was noted after a mean of 14 weeks. Outcome was excellent in 4 patients and good in one. The mean arc of flexion-extension was 101º and the mean arc of supination-pronation was 130º. The mean MEPI was 92. The MEPI was relatively low in the 2 patients with a small osteochondral fragment who underwent Kirschner wire fixation. One patient with articular cartilage damage developed mild degenerative changes and had to change his occupation. The remaining 4 patients were pain-free and had returned to their occupations within 4 months. Open reduction and screw fixation restores articular congruency and enables early mobilisation. Small coronal shear fractures of the trochlea not amenable to screw fixation should be fixed with Kirschner wires.

EXPERIENCES IN TREATING LAUGIER'S FRACTURES

Laugier's fractures are rare because they are located deep in the elbow joint and are thus protected from any direct trauma. This study shows two patients whose Laugier's fractures were surgically treated. Surgical interventions were performed using the Campbell surgical approach. The ulnar nerve was mobilised for a distance of 12 cm, and then a tenotomy of the triceps brachii muscle and a posterior capsulectomy of the elbow joint were performed. A temporary repositioning followed by a permanent fixation were undertaken using two 3.2mm screws. The screws were inserted from the back, through the posterolateral and posteromedial pillars of the humeral condyle, to the front and medially. The tip of the screw was kept subchondrally in the bone of the humeral capitellum or trochlea and did not go through the cartilage. The stitches of the wound were done by layers, and prior to that a transposition of the ulnar nerve was performed medially. A plaster cast was worn on the upper arm for three weeks, with mandatory prophylaxis of periarticular ossification by taking indomethacin, 25mg three times a day. Upon removing the plaster cast, the patients underwent outpatient physical therapy for two weeks followed by inpatient physical therapy with full weight-bearing. Laugier's fractures have been insufficiently described in the literature. Surgical treatment does not have an alternative, and timely diagnosis and surgical and physical therapy yield, according to the Mayo elbow performance index, good results. Acta Medica Medianae 2011;50(4):49-54.

Quantification of Humeroulnar Incongruity inLabradorRetrievers with and without Medial Coronoid Disease

To quantify humeroulnar incongruity on elbow radiographs in Labrador Retrievers with or without medial coronoid disease (MCD). Retrospective study of 92 elbows. Radiographic projections of elbow joints from Labrador Retrievers with MCD (n = 42 elbows; 26 dogs) and without MCD (n = 50 elbows; 25 dogs). The congruity of the humeroulnar joint was measured using an index of subluxation (SI) for each elbow. SI was defined as the distance between the centers of 2 circles drawn along the margins of the incisura trochlearis and the trochlea of humerus on mediolateral digital radiographic projections, normalized by the radius of the circle circumscribing the humeral trochlea. SI was compared between right and left elbows with and without pathology using a Wilcoxon test for paired data, and between normal and abnormal groups with a Wilcoxon test for unpaired data. Mismatch between ulnar curvature and curvature of humeral trochlea and radioulnar incongruency were also noted (Wilcoxon test). The intraobserver repeatability, correlation between SI and radioulnar incongruency, and between SI and mismatch elbow curvature were estimated with a Pearson's correlation coefficient. Intraobserver repeatability of SI measurement was high (r = 0.97). Mean ± SD humeroulnar incongruity (SI) was greater in elbows with MCD (18.5 ± 6.6) than in the normal elbows (1.7 ± 2.0, P < 0.001). The difference between the diameters of the curvatures of the ulnar and humeral trochlea was greater in elbows with MCD (12.5 ± 4.4) than in the normal group (10.7 ± 4.1, P < 0.05). A moderate correlation was found between the degree of humeroulnar incongruity and a radioulnar step (r = 0.63); however, no correlation was identified between SI and the difference between the diameters of the curvatures of the ulnar and humeral trochleae (r = 0.14). We propose a radiographic index to measure humeroulnar incongruity on mediolateral digital radiographic projections. This index (SI) supports the presence of humeroulnar incongruity in Labrador Retrievers with MCD. Further evaluation of its reproducibility and clinical importance are warranted. Although there is a moderate correlation between humeroulnar incongruity and radioulnar incongruency, causation has not been established.

Outcomes of Reduction More Than 7 Days After Injury in Supracondylar Humeral Fractures in Children

Some slightly extended type II fractures initially treated with closed reduction and casting can displace during the first 2 weeks of follow-up. Although closed reduction and percutaneous pinning are desirable for displaced supracondylar humeral fractures treated acutely, there is little or no available information regarding the surgeon's ability to obtain a satisfactory reduction when such a procedure is performed more than a week after the original injury, or the clinical outcome of it. We reviewed the information on 143 type II pediatric supracondylar humeral fractures that were treated by closed reduction and percutaneous pinning. To determine the effect of late treatment, we compared a group of fractures that was treated within the first 7 days (group 1, n=101) with a group that was treated >7 days after the injury (group 2, n=42). Mean time from presentation to surgery was 2.1 days (range, 0 to 5) and 9.8 days (range, 7 to 15) for fractures in groups 1 and 2, respectively. There was no need for an open reduction in either group. An anatomic reduction was obtained in all fractures. There were no iatrogenic nerve injuries, vascular complications, or compartment syndromes in either group. Length of surgery was similar in both groups (P=0.3). There were no significant differences in final carrying angle (P=0.2) or range of motion of the treated elbow (P=0.21). Avascular necrosis of the humeral trochlea was identified in 2 fractures that were treated surgically 8 days after the original injury (group 2). The results of this study suggest that it is possible to obtain an anatomic reduction of a type II pediatric supracondylar humeral fracture even after 7 days from the injury. Such a delay in surgery does not appear to lead to longer surgeries, a higher incidence of open reduction, or to alter the final alignment or range of motion of the elbow. However, the risk of developing an avascular necrosis of the humeral trochlea must be considered. II.

Topographic and age-dependent distribution of subchondral bone density in the elbow joints of clinically normal dogs

To investigate topographic and age-dependent adaptation of subchondral bone density in the elbow joints of healthy dogs by means of computed tomographic osteoabsorptiometry (CTOAM). Animals-42 elbow joints of 29 clinically normal dogs of various breeds and ages. Subchondral bone densities of the humeral, radial, and ulnar joint surfaces of the elbow relative to a water-hydroxyapatite phantom were assessed by means of CTOAM. Distribution patterns in juvenile, adult, and geriatric dogs (age, < 1 year, 1 to 8 years, and > 8 years, respectively) were determined and compared within and among groups. An area of increased subchondral bone density was detected in the humerus distomedially and cranially on the trochlea and in the olecranon fossa. The ulna had maximum bone densities on the anconeal and medial coronoid processes. Increased bone density was detected in the craniomedial region of the joint surface of the radius. A significant age-dependent increase in subchondral bone density was revealed in elbow joint surfaces of the radius, ulna, and humerus. Mean subchondral bone density of the radius was significantly less than that of the ulna in paired comparisons for all dogs combined and in adult and geriatric, but not juvenile, dog groups. An age-dependent increase in subchondral bone density at the elbow joint was revealed. Maximal relative subchondral bone densities were detected consistently at the medial coronoid process and central aspect of the humeral trochlea, regions that are commonly affected in dogs with elbow dysplasia.

Arthroscopic debridement for osteochondral injury of the elbow trochlea: a case report with a long-term follow-up

Q1 Osteochondral injury of the elbow is a rare lesion of the articular surface of the immature joint. A number of cases involving the humeral trochlea of adolescent throwing athletes have been reported in the English-language literature. 6 In the last decade, elbow arthroscopy has evolved to become an accepted technique for the treatment of elbow osteochondral lesions. 8 This is the first report in the literature of the use of arthroscopic debridement for the treatment of a rare osteochondral defect located to the humeral trochlea. Case report A right handedominant 15-year-old female athlete presented with complaints of left elbow pain and limited range of motion (ROM). There was no precedent history of elbow trauma. The patient was a competitive athlete in basketball and swimming. The initial examination by a local orthopaedic surgeon showed a minor elbow extension loss, and an initial diagnosis of triceps tendinitis was made. The diagnosis was based on normal elbow radiographs and a clinical finding of tenderness at the triceps insertion. The orthopaedic surgeon recommended rest and prescribed nonsteroidal anti-inflammatory drugs. However, during the course of the subsequent year, the patient remained active in sporting activities. Despite conservative measures, elbow pain and stiffness persisted, and the athlete was referred to our institution for further evaluation. According to her report, the duration of her symptoms was 1 year. Subsequent physical examination showed limited left elbow ROM from e35 ! of extension to 140 ! of flexion, with full forearm pronation and supination. There was no evidence of elbow swelling or instability. Plain radiographs of the left elbow were again normal (Fig. 1). However, magnetic resonance imaging (MRI) showed a high-signal focus on the posterior-superior surface of the humeral trochlea. The radiologic finding was consistent with an osteochondral lesion. Adjacent to the lesion, another high-signal focus indicated posterior synovial hypertrophy. The triceps tendon itself appeared normal (Fig. 2). On the basis of worsening symptoms, progressive loss of ROM, and MRI findings, a decision for surgical management was made. Q2

Ulnohumeral Chondral and Ligamentous Overload

Background Previous studies have documented increased posteromedial contact forces with the elbow at lower flexion angles associated with valgus extension overload; however, the authors believe that posteromedial elbow impingement in association with valgus laxity is a complex pathological process that may occur throughout the entire throwing motion in the form of ulnohumeral chondral and ligamentous overload. Hypothesis Valgus laxity with the elbow at 90° of flexion may lead to chondromalacia secondary to a subtle shift in the contact point between the tip of the olecranon and the distal humeral trochlea. Study Design Controlled laboratory study. Methods Six fresh human cadaveric elbows were dissected and subjected to a static valgus load. Pressure-sensitive Fuji film measured the contact pressure, contact area, and shift in contact area across the posteromedial elbow before and after sectioning the anterior bundle of the ulnar collateral ligament. Results The contact pressure between the tip of the olecranon process and the medial crista of the posterior humeral trochlea significantly increased, from an average of 0.27 ± 0.06 kg/cm2 to 0.40 ± 0.08 kg/cm2. The contact area also significantly decreased, from an average of 30.34 ± 9.17 mm2 to 24.59 ± 6.44 mm2, and shifted medially on the medial humeral crista, which corresponds to the position of the posteromedial chondral lesions that was observed in throwing athletes in the authors’ clinical practice. Conclusion While simulating the early acceleration phase of the throwing motion with the elbow in 90° of flexion, the results illustrate that abnormal contact may occur as a result of valgus laxity through increased contact pressures across the posteromedial elbow between the medial tip of the olecranon and medial crista of the humeral trochlea. In addition, congruency of the ulnohumeral joint changed, as there was a statistically significant medial shift of the olecranon on the posterior humeral trochlea with the elbow at 90° of flexion after sectioning the anterior bundle of the ulnar collateral ligament. Clinical Relevance In the throwing athlete who continues the repetitive, throwing motion despite valgus laxity from ulnar collateral ligament insufficiency, the authors believe that these results provide a plausible mechanism for injury throughout the entire throwing motion secondary to ulnohumeral chondral and ligamentous overload. As throwing athletes may produce a tremendous amount of force and subsequent chondromalacia within the posteromedial aspect of the elbow, the findings of this study illustrate the importance of prompt clinical recognition of ulnar collateral ligament insufficiency.

Cartilage thickness and split-line pattern at the canine humeral trochlea

To characterise the humeral trochlea in middle to large breed dogs in respect to split-line pattern and cartilage thickness. In 15 paired cadaveric elbow joints of mature dogs (>20 kg body weight) collagen network orientation of the hyaline cartilage of the humeral trochlea was visualised using a traditional split-line technique in which a dissecting needle dipped in India ink was inserted into the cartilage (n = 10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at four representative locations within the joint surface of the humeral trochlea (n = 15). The joint surface of the humeral trochlea showed a distinct pattern of centripetally oriented split-lines with less pronounced or even absent split-lines caudo- proximally towards the olecranon fossa. Median cartilage thickness at the canine humeral trochlea was 0.51 mm (interquartile range: 0.42 - 0.61 mm). Centrally, at the region where osteochondrosis lesions commonly occur in middle to large breed dogs, the median cartilage thickness was 0.55 mm (interquartile range: 0.48 - 0.62 mm). When focusing on anatomical joint resurfacing while performing osteochondral transplantation at the canine humeral trochlea, transplants should be implanted such that their split-lines are oriented centripetally. Hyaline cartilage thickness of transferred grafts should be in the range of half a millimetre to optimally match the situation at the canine humeral trochlea.

Osteochondral lesions of the humeral trochlea in the young athlete

Osteochondral lesions of the humeral trochlea in the young athlete

Aseptic osteonecrosis of the both side humeral trochlea (Hegemann's disease); A case report

Aseptic osteonecrosis of the both side humeral trochlea (Hegemann's disease); A case report

Osteochondral lesions of the humeral trochlea in the young athlete

The purpose of this study was to characterize the variety of osteochondral abnormalities of the humeral trochlea in the pediatric athlete. Patients with trochlear abnormalities were identified through keyword search of radiology dictations from 1999 to 2007. The patient's medical record, imaging studies, and surgical reports were reviewed. The osteochondral lesions were categorized based on the imaging appearance. Surgical results were reviewed in conjunction with the imaging findings. Eighteen patients were identified. Trochlear lesions were stratified into two imaging groups: Osteochondral injury/osteochondritis dissecans (OCD) vs. avascular necrosis (AVN). The osteochondral injury group was stratified into medial and lateral trochlear abnormalities. The medial lesions (n = 3) were small (<6 mm) and were located on the posterior articular surface of the medial trochlea. The lateral lesions (n = 10) were larger (10-14 mm), circumscribed, and were located on the posterior inferior aspect of the lateral trochlea. Trochlear AVN (n = 5) affected development of the lateral trochlea (type A) or both the medial and lateral aspects of the trochlea (type B). AVN occurred exclusively in athletes with history of remote distal humeral fracture. Seven of the 18 patients underwent elbow arthroscopy. Surgical findings and treatment regimens are summarized. Trochlear lesions should be considered in throwing athletes presenting with medial elbow pain and flexion contracture/extension block. Medial trochlear osteochondral injuries may result from posteromedial olecranon abutment. Lateral OCD lesions occur in a characteristic vascular watershed zone resulting from the unique blood supply of the trochlea. Trochlear AVN may be unmasked years following treated distal humeral fracture when the athletic demands upon the adolescent elbow increase, revealing the altered growth and biomechanics.

Prediction of joint center location by customizable multiple regressions: Application to clavicle, scapula and humerus

Accurate spatial location of joint center (JC) is a key issue in motion analysis since JC locations are used to define standardized anatomical frames, in which results are represented. Accurate and reproducible JC location is important for data comparison and data exchange. This paper presents a method for JC locations based on the multiple regression algorithms without preliminary assumption on the behavior of the joint-of-interest. Regression equations were obtained from manually palpable ALs on each bone-of-interest. Results are presented for all joint surfaces found on the clavicle, scapula and humeral bone. Mean accuracy errors on the JC locations obtained on dry bones were 5.2±2.5 mm for the humeral head, 2.5±1.1 mm for the humeral trochlea, 2.3±0.9 mm for the humeral capitulum, 8.2±3.9 mm for the scapula glenoid cavity, 7.2±3.2 mm for the scapular aspect of the acromio-clavicular joint, 3.5±1.8 mm for the clavicular aspect of the sternoclavicular joint and 3.2±1.4 mm for the clavicular aspect of the acromio-clavicular joint. In-vitro and in-vivo validation accuracy was 5.3 and 8.5 mm, respectively, for the humeral head center location. Regression coefficients for joint radius dimension and joint surface orientation were also processed and reported in this paper.

Isolated displaced fracture of humeral trochlea: A report of two rare cases

Fracture of thehumeral trochlea is usually associated with elbow dislocations or capitellar fracture.3-5 Isolated trochlea fracture in adult is a surgical rarity as compared to its capitellar counterpart.5 This fracture is not mentioned in the standard orthopaedic textbook. It only appears sporadically in literature as a case report.2,6,8 The rarity of this fracture is probably a result of its anatomical location which is sited deep within the olecranon fossa. Therefore, there is still very little known regarding the mechanism of injury and the treatment results of this injury. Isolated fracture of the humeral trochlea was first described by Laugier in 1853 and later credited by Stimson. Thus, the trochlea fracture is also sometimes known as Laugier's fracture.7 We would like to report two cases of isolated displaced trochlea fracture that were treated with open reduction and internal fixation using the standard (non-cannulated) Herbert screw (Zimmer, Warsaw, Indiana).

Radiographic study of joint destruction patterns in the rheumatoid elbow

Knowledge of the pattern of joint destruction is important for planning the therapeutic approach to rheumatoid arthritis (RA) of the elbow. Accordingly, we carried out a large-scale radiographic study with the objective of elucidating the joint destruction pattern in rheumatoid elbows. From 2001 through 2003, we examined and took plain X-rays of both elbows of 193 RA patients (i.e., 386 elbows), consisting of 18 men and 175 women, with a mean age of 57.0 years. Radiographic images of the elbow joints were used to classify the degree of bone loss in various zones on the elbow joint surface into four grades of severity, and joint destruction was compared between the left and right elbows. In addition, correlation in the extent of bone loss between each of the zones of the same elbow and differences in the extent of bone loss were analyzed statistically. The results showed direct correlations for destruction of the elbow joint surface among the zones for the left and right elbow joints and in the same elbow joint. However, more severe destruction was observed on the radial side of the humeral trochlea, and it was surmised that destruction of the elbow joint must begin at that site and gradually spread mediolaterally. In addition, in the same elbow joint, the correlation in the degree of bone loss between the trochlea of humerus and the trochlear notch was especially strong, indicating that the bone destruction at both sites represented mirror lesions. We conclude that when performing radiographic diagnosis of the joint damage in the rheumatoid elbow, knowledge of this pattern of joint destruction will be useful for assessing whether there is joint destruction in the initial stage and for deciding the therapeutic approach.

Isolated fracture of the trochlea: A case report

Isolated fracture of the humeral trochlea was originally described by Laugier in 1853 and has since been known as Laugier’s fracture.5 The trochlea rarely fractures in isolation, because it has no muscular or ligamentous attachments and the ulnohumeral joint is not subject to shear forces that occur at the radiocapitellar joint. Thus, trochlear fractures are usually accompanied by other injuries to the elbow. Grant and Miller3 reported a case of an osteochondral fracture of the trochlea occurring as part of a fracture-dislocation of the elbow.

Isolated shear fracture of humeral trochlea

A 30-year-old male was involved in a vehicularaccident while driving a scooter and landed onhis outstretched hand with the elbow in extension.He presented to the casualty department with aswollen elbow held in some degree of flexion.Examination revealed tenderness on the medialaspect of the elbow. Movements at the elbow jointwere painfully restricted. There was no associatedneurovascular deficit. Evaluation of radiographsrevealed a half moon shaped fragment lying prox-imal and anterior to the distal humerus simulatinga capitellar fracture in the lateral view. But onanteroposterior view, the fracture appeared toinvolve the trochlea (Fig. 1). The patient wasplanned for open reduction and internal fixationof the fracture. The joint was opened via a medialapproach. The common flexors were detachedfrom the medial epicondyle and the capsule wasincised. The osteochondral fragment was involvingthetrochlea,withthefracturelineextendinginthecoronalplane acrossthemedial trochlear ridgeinto the trochlear notch. The fragment was dis-placed proximally and rotated internally. The frac-ture was reduced and fixed with two 4.0 mmpartially threaded cancellous screws passed fromthe non-articular area. The elbow was immobilisedin a POP back splint and early active range ofmotion exercises were encouraged at 5 days whenthe patient was pain free. A removable splint wasworn for the first 6 weeks during which period thepatient was instructed to carry out the exerciseson his own. Muscle strengthening and further reha-bilitation was initiated after 6 weeks once signs of

Posterolateral Rotatory Instability of the Elbow

Posterolateral rotatory instability of the elbow is a three-dimensional displacement pattern of abnormal external rotatory subluxation of the ulna coupled with valgus displacement on the humeral trochlea. This pattern causes the forearm bones to displace into external rotation and valgus during flexion of the elbow. Injury to the lateral ulnar collateral ligament allows abnormal supination of the ulna on the humerus. The radial head, being locked in the sigmoid (radial) notch of the proximal ulna by the annular ligament, subluxates posterior to the capitellum. The abnormality is usually posttraumatic and presents with locking, snapping, clicking, catching, and recurrent dislocation of the elbow. The clinical diagnosis is suspected from history and confirmed by the physical examination, which includes the posterolateral rotatory instability test. This test often is best performed under fluoroscopy or general anesthesia. Usually the instability is managed with either a repair of the ligament or an isometric reconstruction using a tendon graft.