Posterior Impingement Research Articles

Etiology and Treatment of Delayed-Onset Medial Malleolar Pain Following Total Ankle Arthroplasty.

Total ankle arthroplasty (TAA) has become a successful treatment for end-stage ankle arthritis. Some patients may still have pain or may present with new pain. Suggested sources of medial pain include tibialis posterior tendonitis, impingement, or medial malleolar stress fracture. Etiology and treatment remain unclear. The objective of our study was to evaluate patients with delayed-onset medial malleolar pain following TAA who underwent treatment with percutaneous medial malleolar screw placement and propose an etiology. Patients who had undergone TAA at our institution were reviewed and those with medial malleolar pain were identified. Clinical and radiographic examinations were performed pre- and postoperatively. Radiographs were compared with those from a cohort of controls without a history of medial pain. All affected patients failed conservative therapy and were treated with percutaneous placement of medial malleolar screws positioned from the malleolar tip and extending proximally beyond the tibial component. Postoperatively, patients were placed in an ace wrap and allowed to be weightbearing to tolerance, except for 1 patient initially restricted to partial weightbearing. Visual analog scale (VAS) scores were recorded. Seventy-four (74) patients underwent TAA by the corresponding author. All (100%) were female with an average age of 66 (range, 57-73) years. Average follow-up since screw placement was 21.4 (range, 10-41) months. Six (8.1%) underwent placement of 2 percutaneous medial malleolar screws. Patients presented with pain an average of 12 (range, 4-24) months postoperatively and underwent screw placement an average of 2.8 (range, 1-6) months after presentation. At the time of TAA, none had a coronal plane deformity and none underwent a deltoid ligament release as part of balancing. All (100%) patients had pain and swelling directly over the medial malleolus prior to screw placement. Postoperatively, 1 (17%) had mild pain clinically at this site and 2 (33%) had occasional pain medially with activity. Average VAS scores improved from 5.7 (range, 4-6) preoperatively to 1.3 (range, 0-3) postoperatively (P < .05). Three (50%) patients had a bone density test and all were normal. Prior to screw placement, radiographs demonstrated no signs of stress fracture or misalignment. Average minimum width of the medial malleolus at the level of the tibial component was 10.2 mm (range, 9.2-11.0), which was significantly less (P < .05) than the control group of 19 patients whose distance measured 12.2 mm (range, 8.5-14.8). Patients who present with new-onset medial malleolar pain with normal radiographs following TAA may have medial malleolar insufficiency fracture. These patients can be treated successfully with minimal morbidity by placement of percutaneous medial malleolar screws. Etiology may be related to deltoid traction, subacute stress fracture, and/or impingement of the talus component on the medial malleolus. Medial malleolar pain may be misdiagnosed as tibialis posterior tendonitis, impingement, or implant failure. This diagnosis should be considered in patients who have pain at the medial malleolus, particularly if they are female or have medial malleolus thickness less than 11 mm at the level of the tibial implant. Placement of prophylactic medial malleolar screws may be considered at the time of TAA when these conditions exist. Level IV, case series.

A Rare Cause of Neuropathic Pain in the Back: Notalgia Paresthetica.

Notalgia paresthetica (NP) is a neuropathy with unknown cause of thoracic spinal nerves T2-T6, particularly their dorsal branches. It is a chronic disease that can be seen among the elderly and females. Despite its unknown etiology, NP is thought to result from posterior spinal nerve impingement or chronic nerve trauma. In addition, increased dermal innervation and viscera-cutaneous reflex mechanisms are other mechanisms responsible for their chemical neurotoxicity. It is a clinical condition associated with a character of neuropathic pain, itching, and nonspecific skin lesions with brown pigment in both the dorsal vertebrae and scapular areas (1).

True Angle between Anterior-Posterior Impingement in Total Hip Arthroplasty: Why Common Constrained Cups have to Fail

Background: Dislocation after total hip arthroplasty is a common complication and partially based on impingement. Questions/purposes: (1) The purpose of this study was to investigate the angle between anterior and posterior impingement in current hip cup designs. (2) Furthermore, the aim was to design a model of an acetabular cup with sparing gaps that match to impact areas. Methods: The range of motion was simulated with Maple R8 software using standard parameters in hip arthroplasty. Afterwards, a preliminary model for an optimized acetabular cup was designed in order to avoid impingement and dislocation. Results: (1) Anterior and posterior areas of impingement were not opposite but twisted by an angle of 108.3°. (2) The two main trajectories of motion were identified and areas with corresponding reductions and elevations were appropriate modified. The improvement resulted in a “bidirectional total hip prosthesis” with a combination of a snapfit acetabular cup and a reduced cup profile. Conclusion: The improvements of the described hip prosthesis are based on a simulation and are most likely to prevent impingement and subsequent dislocation. In addition, simulation with standard implantation parameters resulted in a rotational asymmetric implant design. Clinical relevance: Our data provide evidence that conventional hip cup designs fail to prevent impingement due to (1) The incorrect assumption of diagonally arranged impingement areas and the diagonal arranged sparing gaps (2) The sparing gap design itself that technically is not reducing the rim of the cup but instead only has an elevated coverage relative to the center of motion.

Olekranon Sıkışma Sendromu Olan Bir Olgunun Fonksiyonel Sonuçları: Konservatif Tedavi Yaklaşımları

Olecranon impingement is a rare condition in general population; however, it is usually seen in overhead athletes; however, it is usually seen in overhead athletes. Repetitive combined hyperextension, valgus, and supination of the elbow, resulting in a mechanical abutment of bony or soft tissues in the posterior fossa of the elbow aggravate the problem. Complains of pain posteriorly, joint effusion, locking, crepitus, and a decrease in range of motion, most notably an extension deficit are most common. Although conservative treatment of posterior impingement is rare, arthroscopy of the elbow can be a radical option at the beginning. The unusual case of an olecranon impingement syndrome at right elbow in a female patient is reported here. The patient was treated with conservative rehabilitation approaches for 8 weeks and returned to painless daily activities.

Treatment of posterior and anterior ankle impingement syndrome with combined anterior, tarsal sinus and posterolateral approaches under arthroscopy

Objective To discuss the methods and effects of arthroscopic treatment of posterior and anterior ankle impingement syndrome through anterior approach, tarsal sinus approach plus posterolateral approach. Methods The study enrolled 12 patients with posterior and anterior ankle impingement syndrome treated from January 2012 to March 2014. There were 8 males and 4 females, aged17-65 years (mean, 45 years). Left ankle injury was noted in 9 patients and right ankle injury in 3 patients. Eight patients had a history of obvious ankle injury (5 acute and 3 chronic sprains). Arthroscopic surgery was performed to manage the posterior and anterior ankle impingement syndrome through the combined anterior, tarsal sinus and posterolateral approaches, and prone position and posteromedial incision were not used during operation. Postoperative outcome was evaluated using the American Orthopedic Foot and Ankle Society (AOFAS) score. Results Operation time was 45-80 min (mean, 62 min). Arthroscopy confirmed anterior bone impingement in all patients. Three patients suffered from posterior bony impingement of the talus, while nine patients os trigonum injury. Duration of follow-up was 10-18 months (mean, 14 months). AOFAS score was (91.4±6.5)points after operation, significantly higher (34.4±12.6)points before operation (t=14.607, P<0.01). All patients had normal ankle range of motion after operation. There were no complications such as neurovascular injury. All the surgical incisions achieved primary healing. Conclusion The procedure avoids body position shift and posteromedial incision during operation, and attains a good vision to the anterior and posterior portions and satisfactory short-term outcome. Key words: Ankle injuries; Arthroscopy; Impingement

Outcome of Arthroscopic Treatment of Posterior Impingement of the Ankle.

Open and arthroscopic techniques have been utilized in the treatment of posterior impingement of the ankle and hindfoot. Because posterior impingement occurs more frequently in patients who repetitively plantarflex the ankle, this population may especially benefit from a procedure that reduces pain and results in maximal range of motion (ROM). The purpose of this study was to assess the outcome of hindfoot endoscopy in patients with posterior ankle impingement through a higher level of function outcome measures and physical examination parameters, focused on analysis of ROM. Twenty patients were followed prospectively at a minimum 1-year follow-up (mean 38.2 months). Nineteen of 20 patients were competitive athletes. Patients completed a minimum of 3 months of nonoperative treatment. Diagnoses included os trigonum, tibial exostosis, talar exostosis, loose body or fracture nonunion, and ganglion cyst removal. Patients underwent arthroscopic treatment utilizing a posterior approach; all relevant pathology was addressed. At the most recent follow-up, visual analog scale pain and American Orthopaedic Foot & Ankle Society hindfoot scores showed significant improvement (P < .01) pre- to postoperatively; Tegner score remained unchanged (P = .888). Three patients were professional athletes; all returned to their previous level of professional activity. ROM variables between affected and unaffected sides reached statistical similarity at the most recent follow-up. Only ankle plantarflexion reached statistical significance when compared pre- to postoperatively. Fifteen percent of patients reported postoperative neuritis. Posterior ankle arthroscopy allowed for maintenance or restoration of anatomic ROM of the ankle and hindfoot, ability to return to at least previous level of activity, and improvement in objective assessment of pain relief and higher level of function parameters. Complications associated with this procedure were minimal. Level IV, retrospective case series.

Posterior impingement syndrome of the ankle

Posterior impingement syndrome of the ankle

Posterior Arthroscopic Subtalar Arthrodesis.

Although subtalar joint arthrodesis may be achieved through open or arthroscopic approaches, we have found that posterior arthroscopic subtalar arthrodesis has technical advantages compared with other approaches. Clinically assess the foot and ankle with regard to remaining motion, previous scarring, and associated deformities, ensuring that no concomitant procedure will be needed in the supine position. Use spinal or general anesthesia. Place the posterolateral portal lateral to the Achilles tendon at the level of the tip of the lateral malleolus, according to the original technique described by van Dijk et al. Place the posteromedial portal medial to the Achilles tendon at the level of the tip of the lateral malleolus. With the help of the shaver, look for the landmarks of the posterior arthroscopy, going from the posterolateral part of the subtalar joint toward the flexor hallucis longus tendon, which is medially located, while exposing the tibiotalar joint. Sometimes an accessory portal, just anterior to the tip of the external malleolus, may be needed to achieve a distraction of the anterior part of the subtalar posterior facet. To perform this concomitant step, which generally is not necessary, use an arthroscopic forceps to insert a 5 by 20-mm autograft or allograft in the subtalar joint. Use two cannulated screws with a 7.3-mm diameter; we prefer stabilization screws to compression screws. Always clean out the posterior compartment of the ankle during the PASTA procedure, as is done during surgical treatment for posterior impingement syndrome, and note that both posterior impingement syndrome and subtalar degenerative changes may thereby be easily addressed through this procedure. A short posterior leg splint is worn for three to ten days, followed by another non-weight-bearing cast for another three weeks. Since the appearance of the original article, a total of forty-one unilateral subtalar joints in twenty-five men and sixteen women, seen between May 2007 and December 2012, with isolated subtalar arthritis or talocalcaneal coalition without any other major hindfoot arthritis were treated by posterior arthroscopic subtalar arthrodesis, and all subtalar joints except for two were considered radiographically fused at the first attempt after an average of 6.7 weeks (range, six to ten weeks).IndicationsContraindicationsPitfalls & Challenges.

Features of treatment for posterior impingement in sportsmen and ballet dancers

35 posterior ankle arthroscopies for posterior ankle impingement were performed within the period of time between January 2014-April 2015. Radiological investigation and MRI were held preoperatively. The examinations and operations revealed the following findings: os trigonum 21 (60%), posterior lateral fracture 6 (17%), Stieda process 8 (23%). The patients were tested on the scale of AOFAS pre and post-operatively. In comparison with preoperational period all the patients recognized the decrease or full disappearance of pain syndrome as well as functional improvements (AOFAS 59,8 preoperatively to 93,9 2 months postoperatively). The posterior ankle arthroscopy is an efficient and relatively safe method for posterior ankle impingement treatment which works efficiently to eliminate or decrease pain syndrome and helps to recover the function of plantaris.

Arthroscopic Debridement After Total Ankle Arthroplasty.

Residual pain due to impingement after ankle arthroplasty can be addressed with arthroscopic debridement. Literature focusing on the effectiveness of arthroscopic debridement after total ankle arthroplasty (TAA) is scarce. The authors report a case series of 12 patients complaining of anterior or posterior impingement pain, 11 of which were in the absence of malalignment which were treated by arthroscopy. Of the 106 TAAs performed between 2003 and 2012, a total of 12 subjects reported postoperative pain resulting from anterior or anteromedial impingement, medial and/or lateral gutter impingement, posterior impingement, and/or ankylosis. All patients were reviewed on a regular basis through chart review, clinical examination, and radiologic evaluation. The average time to final follow-up was 58.8 months. The average period from the original TAA to the arthroscopic debridement was 38.2 months. The median AOFAS hindfoot score was significantly (P < .05) improved from 64.6 preoperatively to 73.5 postoperatively. Eight subjects reported good pain relief after the arthroscopic debridement, and partial pain relief was reported by 4 subjects. Three patients with painful ankylosis had no improvement in the total range of motion of the TAA implant after the arthroscopic debridement. The results suggest that arthroscopic debridement in patients with residual pain due to impingement syndromes after TAA was effective in 8 of the 12 cases at 2 years' follow-up. However, the results suggest that arthroscopic debridement in the presence of painful ankylosis associated with or without impingement syndromes results only in partial pain relief and does not improve the range of motion. Level IV, case series.

Endoscopic treatment of the posterior ankle impingement syndrome on amateur and professional athletes.

To determine whether professional and amateur athletes showed differences in ankle function when treated with endoscopic technique for posterior ankle impingement syndrome, to verify the impact of the presence of associated lesions in clinical evolution and to assess time to return to sport (we hypothesize that time will be the only difference between groups). Thirty-two athletes with a diagnosis of posterior impingement syndrome underwent surgery endoscopically. The American Orthopaedics Foot and Ankle Society (AOFAS) scale was used to compare functional results between amateur (15) and professional athletes (17). The satisfaction, time to return to sport, operative time, intraoperative findings and complications were evaluated, and the presence of associated injuries interfering in these results was verified. The preoperative AOFAS score range for the professional group was 62.9 ± 14 preoperatively and 92.3 ± 7.7 postoperatively, and for the amateur group was 67.9 ± 19.7 and 94 ± 9.3. The satisfaction was excellent or good in 94 % of all cases and fair in 6%. The average time of surgery was 48.3 + 25 min. Bone involvement was present in 100% of cases and complications in three cases. Time to return to sports was similar (n.s.) in both groups, and the mean time was 15.6 ± 13.7 and 16.3 ± 9 weeks, respectively. No significant difference regarding functional results and time to return to sports between professionals and amateur athletes operated was found. Athletes showed mainly good and excellent results and low complication rate. The presence of associated injuries did not significantly influence the results. With these results, the high-level athlete can better programme their surgeries so they can fully recover and perform better in the most important competitions. Level III.

Biomechanical Alignment of Main Wear-Pattern on MOM Total Hip Replacement

In the majority of retrievals, femoral heads and cups are sent for analysis with no designation as to positioning in-vivo. In addition, when patients retain the femoral prosthesis, evidence of neck impingement damage is lost. In this case report we studied head and cup wear-patterns and stripe damage in a novel case that included a large diameter metal-on-metal THA that was retrieved with the head still fused to the stem. This provided anatomical positioning of head wear-pattern and stripe damage as represented by the orientation of the femoral stem in radiographic images. We investigated (1) size, shape and location of head and cup wear-patterns, (2) cup-to-stem impingement damage, and (3) head stripe-wear. The head wear-pattern was elliptical in shape, 40mm diameter with area covering 2200 sq.mm. Its hemispherical ratio was 56% with aspect ratio 1.2 and typical of large-diameter MOM retrievals. Wear-pattern extended from 12° above superior head-margin to approximately 40° inferior to polar axis. Centroidal vector in coronal plane was 13° posterior to polar axis and in transverse plane was 19° superior to polar axis. These vector data corresponded well with biomechanical predictions of resultant load axes in gait studies. Stripe damage was identified on the head, and the cup rim could thereby be aligned to verify neck impingement and also head subluxation mechanisms. Cup wear-pattern was not centrally contained, indicating this patient had experienced repetitive edge-wear during gait. Thinning of the cup rim by 350- 400μm indicated that posterior impingement with repetitive anterior subluxation of the head had created this edge-wear.

Management of Posterior Impingement in the Ankle in Athletes and Dancers.

Management of Posterior Impingement in the Ankle in Athletes and Dancers.

Arthroscopic Treatment of Posterior Impingement of the Hindfoot

Objectives:Open and arthroscopic techniques have been utilized in the treatment of posterior impingement of the ankle and hindfoot. Because posterior impingement occurs more frequently in patients who repetitively plantarflex the ankle, this population may especially benefit from a procedure that reduces pain and results in maximal range of motion (ROM). The purpose of this study was to assess the outcome of hindfoot endoscopy in patients with posterior ankle impingement through higher level of function outcome measures and physical examination parameters, focused on analysis of ROM.Methods:20 ankles (19 patients) were followed prospectively at a minimum 1 year follow-up (mean 38.2 months). 19 of 20 patients were competitive athletes. Patients completed a minimum of 3 months of nonoperative treatment. Diagnoses included os trigonum, tibial exostosis, talar exostosis, loose body or fracture nonunion, and ganglion cyst removal. Patients underwent arthroscopic treatment utilizing a posterior approach; all relevant pathology was addressed. Post-surgery, patients were placed in a splint for 3 to 7 days then placed in a CAM boot for 2 to 3 weeks, weight bearing as tolerated. Physical therapy was initiated within 7-10 days; strengthening exercises were initiated postoperatively at 1 month.Results:At most recent follow-up, VAS Pain and AOFAS Hindfoot scores showed significant improvement (p<0.01) pre to post-operatively; Tegner score remained unchanged (p=0.888). 3 patients were professional athletes; all returned to their previous level of professional activity. ROM variables between affected and unaffected sides reached statistical similarity at most recent follow-up. 15% of patients reported post-operative neuritis. No other complications were reported.Conclusion:Posterior ankle arthroscopy allows for maintenance or restoration of anatomic ROM of the ankle and hindfoot, ability to return to at least previous level of activity, and improvement in objective assessment of pain relief and higher level of function parameters. Complications associated with this procedure are minimal.

Anatomical characteristics of the flexor digitorum accessorius longus muscle and their relevance to tarsal tunnel syndrome a systematic review.

Clinical and cadaver studies have reported that supernumerary muscles could be the etiology of a variety of pathologic disorders, such as posterior impingement syndrome, tarsal tunnel syndrome (TTS), and flexor hallucis longus tenosynovitis. We describe a unique variant of the flexor digitorum accessorius longus (FDAL) muscle as an apparent cause of TTS, functioning as an independent flexor of the second toe, which has not been described in the literature. In addition to this case report, a systematic review was performed of TTS caused by the FDAL muscle. A targeted search of PubMed, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, and Web of Science identified full-text papers that fulfilled the inclusion and exclusion criteria. Twenty-nine papers were identified for inclusion in the systematic review: 12 clinical papers of TTS caused by the FDAL muscle and 17 cadaver-based papers. Clinicians often do not include the FDAL muscle in the differential diagnosis of TTS. This literature review suggests that the FDAL is an important muscle in terms of its functional and clinical significance. Knowledge of this muscle, its anatomical location and variations, and its magnetic resonance imaging characteristics may help clinicians make an accurate differential diagnosis.

Critical analysis of olecranon fracture management by pre-contoured locking plates

BackgroundFractures of the proximal ulna are rare and usually managed surgically. Strong fixation of the harware is essential to obtain good outcomes. We report our experience with pre-contoured locking plate fixation of complex olecranon fractures and present a critical appraisal of the outcomes. HypothesisPre-contoured locking plates provide good outcomes, but their clinical tolerance may be limited in some instances. Materials and methodsFrom September 2009 to December 2011, 28 patients were managed using a pre-contoured locking compression plate (LCP®). Among them, 6 were excluded because of missing data, which left 22 patients (11 males and 11 females) with a mean age of 55.7 years, including 12 who were employed. The fracture was on the dominant side in 11 patients. According to the Mayo Clinic classification, 15 fractures were type II and 7 type III. In addition to the ulnar fracture, a radial head fracture was present in 9 patients and a coronoid process fracture in 5 patients. Functional recovery was assessed using the Broberg-Morrey score and Mayo Elbow Performance Score (MEPS). Radiographs were obtained to evaluate the quality of fracture reduction and fracture healing, as well as to look for ossifications and osteoarthritis. ResultsMean follow-up was 20 months. Flexion was 131°, extension loss was 9.5°, pronation was 79°, and supination was 80.5°. The mean Broberg-Morrey score was 96.7 and the mean MEPS score 96.6. Fracture healing occurred in all patients, within a mean of 10.6 weeks. Evidence of early osteoarthritis was found in 6 patients, ossifications in 3 patients, and synostosis in 1 patient. An infection was successfully treated with lavage and antibiotic therapy in 1 patient. The fixation hardware was removed in 6 patients. No prognostic factors were identified. Discussion-conclusionOur hypothesis was confirmed. The outcomes are encouraging and comparable to those reported in the literature. The critical issue is the limited clinical tolerance of the plate with a high rate of posterior impingement requiring plate removal (27%). Rigorous technique is essential during plate implantation. Level of evidenceLevel IV, retrospective study.

Measuring extension of the lumbar-pelvic-femoral complex with the EOS® system.

Sagittal balance of the coxofemoral joint in standing position and its extension capacity determine hip/spine adaptation, especially in relation to pelvic retroversion, which may be age-associated or follow either spinal arthrodesis or vertebral osteotomies. The concept of extension reserve is essential for assessing posterior hip impingement. The global visualization of the lumbar-pelvic-femoral complex obtained by EOS(®) imaging enables this sagittal analysis of both the subpelvic region and lumbar spine by combining the reference standing position and the possibility of dynamic tests. We studied 46 patients and their 92 hips. The EOS(®) radiography was performed in neutral standing position and with one foot on a step, alternately the right and left feet. Pelvic incidence, sacral slope, pelvic version, and femoral version were measured twice by two operators. The global extension reserve (GER) was defined by the sum of the intrinsic extension reserve (allowed by the hips, IER) and the extrinsic extension reserve (allowed by the spine, EER). The IER for each hip corresponds to the difference in the sacrofemoral angle (SFA) for each of the two positions. The EER was measured by the difference in the sacral slope. A descriptive study was performed, together with studies of inter- and intra-observer reproducibility, right/left symmetry, and an analysis according to age, sex, and BMI. The mean femoral version in the reference position was 11.7° (SD 14.3°). The reproducibility of the SFA measurement was statistically verified. The IER (mean 8.8°), EER (mean -0.7°), and GER (mean 8.2°) all differed significantly between the two sides for each patient and were not associated with age, sex, or BMI. The femoral axis is not perpendicular to the ground in neutral position, contrary to the conventional view of this position. The measurements proposed for dynamic sagittal analysis of the hip are reproducible and make it possible to identify the IER within the GER of the spinal-pelvic-femoral complex. The assessment of the lumbar-pelvic-femoral complex by EOS imaging makes it possible to define the intrinsic and extrinsic extension reserves to describe the reciprocal adaptive capacities of the hips and spine. IV.

A case report of posterior elbow impingement by fat pad injury

A case report of posterior elbow impingement by fat pad injury

An Unusual Cause of Posterior Elbow Impingement: Detachment of a Hypertrophied Posterior Fat Pad.

We report a case of a 47-year-old woman who developed posterior impingement of the elbow due to detachment of a hypertrophied posterior fat pad. She reported acute left elbow pain after leaning back onto a hard object with her hand and subsequently experienced a “catching” sensation. Comparison with the magnetic resonance images of a normal elbow revealed a hypertrophied posterior fat pad interposed between the olecranon and olecranon fossa in both elbows, with the fat pad in the left elbow located more inferiorly than that in the right elbow. Elbow arthroscopy showed the olecranon fossa covered by the fat pad, a portion of which was detached from the rest of the pad. Debridement of the detached portion was performed until no impingement was evident. Postoperatively, full extension of the elbow did not elicit pain. Clinicians should include this pathology among the differential diagnoses for posterior elbow pain.

Glenohumeral instability

• Normal anatomical variants: ○ Sublabral foramen ○ Sublabral recess ○ Buford complex ○ Capsular insertions • Shoulder instability: ○ Anterior glenohumeral instability • Anteroinferior labral tear ○ Bankart lesion ○ Anterior labroligamentous periosteal sleeve avulsion lesion ○ Perthes lesion ○ Glenolabral articular disruption lesion • Extensive anterior labral tear • Anterosuperior labral tear • Glenohumeral ligament injury ○ SLAP lesion ○ Posterior glenohumeral instability ○ Posterior superior glenoid impingement MR arthrography is useful in diagnosing and characterizing the labral–ligamentous lesions resulting in glenohumeral instability. The sublabral foramen, sublabral recess and Buford complex are normal variants of the glenoid labrum, which must not be confused with true labral abnormalities. The most common type of glenohumeral instability is anteroinferior instability, characterized by avulsion of the anteroinferior labral–ligamentous complex, which is termed a Bankart lesion. Variants of the Bankart lesion, where the scapular periosteum remains intact, are the anterior labroligamentous periosteal sleeve avulsion lesion, the Perthes lesion and the glenolabral articular disruption lesion. Anterosuperior labral tears are uncommon and must be differentiated from a normal sublabral foramen. Anterior glenohumeral instability also occurs following injury to the glenohumeral ligaments, most commonly described as humeral avulsion of the inferior glenohumeral ligament lesion. The superior labral anteroposterior (SLAP) lesion is a superior labral tear that extends both anterior and posterior to the biceps tendon attachment. SLAP lesions have a complex classification but the presence and the extent of biceps tendon involvement is the most important feature. A SLAP II lesion must be distinguished from a normal sublabral recess. Patterns of injury seen in posterior instability are the reverse of those found following anterior dislocation with posterior labral tears referred to as a reverse Bankart lesion. Posterior superior glenoid impingement or internal impingement is when the posterosuperior aspect of the glenoid and the humeral head come into contact, causing injury to the interposed rotator cuff and posterosuperior labrum.