Posterior ankle arthroscopy: current state of the art

Defining a Safe Zone for Percutaneous Screw Fixation of Posterior Malleolar Fractures

Posterior malleolar fractures require fixation to confer stability to the ankle. Although some have suggested that fractures involving less than 25% of the articular surface require no intervention, estimation of malleolar size on plain imaging is inaccurate. Some posterior malleolar fractures may be particularly suitable for posterior-to-anterior percutaneous screw fixation of the posterior malleolus via a posterolateral approach. We hypothesized that there may be a safe zone in the posterolateral ankle, identifiable with reliable anatomic landmarks, that might allow safe percutaneous screw placement for fracture fixation. The study protocol involved Step 1, in which multiple Kirschner wires were used in a single cadaveric specimen to attempt to identify a safe zone entry point in the posterior ankle, and Step 2, in which a single wire was used in each of six additional cadaveric specimens to test the ability to safely replicate the use of that entry point. In Step 1, a safe zone entry point was identified, located immediately lateral to the Achilles tendon and 1 cm above the level of the tip of the medial malleolus, when visualizing the posterior ankle. In Step 2, using these landmarks and an image intensifier, single wires were then successfully placed in the other six specimens without injury to any significant structure. If confirmed in clinical studies, the safe zone entry point that we have identified could potentially be used to facilitate posterior-to-anterior percutaneous fixation in patients with posterior malleolar fractures for whom open reduction may not be required or may be contraindicated.

Arthroscopic Posterior Ankle Ligament Anatomy

BACKGROUND

The purpose of this article is to document the normal arthroscopic appearance of the posterior ankle capsular and ligamentous structures, and variations in their anatomical relationships.

METHODS

102 ankle arthroscopy videotapes were evaluated retrospectively for the configuration of the posterior capsuloligamentous structures. Based on these observations, the variations in the appearance and position of the posterior tibiofibular ligament (PTFL) and transverse (tibiofibular) ligament (TTFL) were documented. In addition, differences in the appearance of the flexor hallucis longus (FHL) were also noted.

RESULTS

All patients had evidence of both a PTFL and TTFL, which formed a labrum or meniscus-like addition to the posterior distal tibia. No patients demonstrated disruption of the PTFL; 3 had tears of the TTFL. We noted 4 distinct patterns of the PTFL and the TTFL. Thirty-four patients (33%) had a gap of ≥2 mm between the 2 ligamentous structures. Thirty-three (32.4%) had a gap <2 mm between the PTFL and TTFL. Twenty-six (25.5%) had a confluence of the 2 ligaments without a gap. Nine (9%) demonstrated a sizable gap between the 2 ligaments, and the TTFL appeared as a "cord-like" structure.

CONCLUSION

To our knowledge, this is the first article to describe the variations in the arthroscopic normal posterior capsuloligamentous structures and FHL of the ankle.

LEVEL OF EVIDENCE

Level IV, case series.

Chronic lateral ankle instability increases the likelihood for surgery in athletes with os trigonum syndrome

PURPOSE

The etiology and incidence of os trigonum syndrome in professional athletes is highly variable. There is a paucity of data to ascertain why some athletes evolve towards surgery whilst others remain asymptomatic. We hypothesized that a lateral ligament ankle injury would increase the likelihood for surgery in those athletes with os trigonum syndrome.

METHODS

Eighty professional athletes with clinical and radiological signs of os trigonum syndrome were identified to ascertain the incidence of injury to the lateral ligamentous ankle complex (acute and chronic) by magnetic resonance imaging (MRI). This cohort was subdivided into 2 groups; a surgical (n = 40) and a non-surgical (n = 40) cohort. Surgical division was decided if (1) the clinical hyper-plantar flexion test was positive, (2) a positive diagnostic ultrasound-guided injection and (3) no improvement was observed after 6 weeks of conservative rehabilitation.

RESULTS

From the surgical cohort, 37 players (94.1%) had a chronic lateral ankle ligament injury on MRI, whilst 3 players (5.9%) had an acute lateral ankle ligament injury. Binary logistic linear modelling revealed that having a chronic lateral ligament injury increases the likelihood of os trigonum syndrome surgery by ten times compared to those with an acute lateral ligament injury.

CONCLUSION

Professional athletes with chronic lateral ligament ankle injury have an approximate ten times greater risk for os trigonum syndrome surgery compared to athletes with acute lateral ligament ankle injury.

LEVEL OF EVIDENCE

IV.

Endoscopic treatment for posterior ankle impingement: high patient satisfaction and low recurrence rate at long-term follow-up

Objectives

Good short-term outcomes have been described for endoscopic treatment of posterior ankle impingement. However, long-term outcome is unknown. The aim of this study is to determine the long-term patient satisfaction after endoscopic treatment and evaluate the recurrence rate of posterior ankle impingement. In addition, the aim of this study is to identify factors associated with favourable long-term outcome.

Methods

A consecutive series of patients treated endoscopically for posterior ankle impingement between 2000 and 2011 in the Academic Medical Centre in Amsterdam were retrospectively reviewed. Primary outcome was patient satisfaction. Secondary outcome measures were function, pain, recurrence rate and Foot Ankle Outcome Scores. In addition, factors associated with long-term outcome were identified.

Results

Two-hundred and three patients with 5–15 years of follow-up were included. Median satisfaction score was 8/10 and for 9/10 for function . Patients had no pain at follow-up. Outcome was similar for different types of impingement and type or level of sport participation. Symptoms recurred in 5% of the patients. In a multivariable analysis, additional flexor hallucis longus (FHL) tendinopathy was associated with lower satisfaction and a higher recurrence rate.

Conclusion

Long-term outcome of endoscopic treatment for posterior ankle impingement demonstrated good results, with high patient satisfaction, good functional outcome scores and a low rate of recurrence for all types of posterior ankle impingement. Type and level of sports did not influence outcome. Only the presence of FHL tendinopathy was associated with lower satisfaction and a higher recurrence rate.

Level of evidence

Level IV.