Anterior Ankle Impingement
Ankle impingement may be found on the anterior or poste- rior aspect of the ankle joint. When the impingement is located posteriorly, either an os trigonum or a prominent posterior process of the talus will be frequently found. This condition will not be covered in this chapter as it is not
A B
FIGURE 5–2.(A) Surgical setup for ankle arthroscopy. The weights applied to the foot are supported by an elastic bandage, which allows full mobility of the surgeon at the end of the table. (B) Similar setup with a drape covering the weights to guarantee sterility during the procedure.
39 C H A P T E R5 Ankle Arthroscopy
related to an arthritic process of the ankle and more likely to an overuse injury or syndrome of the ankle posterior joint.
Anterior ankle impingement (AAI) may be soft tissue or bony in nature. When a soft tissue AAI takes place, it is frequently secondary to previous trauma to the ankle joint and the creation of an increased and abnormal inflammatory response. The synovial tissue will have an excessive respond to an intra-articular hematoma. In some instances, formation of tissue may take place. Pseudo meniscus tissue has been described as a source of residual pain after an ankle sprain.9,10 The soft tissue AAI will not be discussed in this chapter.
Bony AAI was originally coined as “footballer’s ankle.”11 A clear etiology of the formation of anterior bone spurs for both the distal tibia and superior aspect of the talus is still unknown. For a long time, it was hypothesized that it was the result of traction osteophytes from the most anterior aspect of the capsule of the ankle joint.11 However, it has been point out recently12that if this were the case, visualiza- tion of the osteophytes during an arthroscopic approach would be very difficult and the osteophytes could have not been visualized in their entirety. However, it is well accepted that the osteophytes remain 100% intra-articular for both the dorsal aspect of the talus and the distal aspect of the tibia. Visualization of the osteophytes usually is not a prob- lem. In some instances, some hypertrophic synovitis may make visualization a little bit more demanding, but after debridement of synovial tissue, both osteophytes should be rather accessible.
Berberian et al.13reported very elegantly on an anatomic description of the location and shape of the anterior osteo- phytes of the ankle joint. They reviewed a total of nine com- puted tomography (CT) scans from patients who underwent surgical resection of their anterior ankle osteophytes. They concluded that the distal tibia osteophyte will be located lat- eral to the midline and the dorsal talar osteophyte will occur more medial to the midline. They also emphasized the fact that the osteophytes do not contact each other and they have a more “scissoring” effect between the two. In addition, the distal tibia osteophyte has a wider base than the talar one.
The population most likely affected by AAI is consti- tuted by athletic individuals with a history of being ankle abusers. Most likely, they would present in the late portion of their third decade of life or some time along their fourth decade. It is unusual for these patients to report on a single injury as a source of discomfort. A history of multiple epi- sodes of minor trauma to the ankle will likely be present.
Symptoms are described as pain and stiffness and having difficulties with dorsiflexion of the ankle joint. For those involved in jumping activities, most of the problems will arise from their limited ability to proceed with powerful takeoffs or vertical jumps due to the limited dorsiflexion. Chronic irritation will be present, and some occasional diffuse ante- rior edema may also be reported.
On physical examination, the patient will have some lim- ited dorsiflexion and particularly some pain and difficulties with palpation of the most anterior aspect of the ankle joint.
The ankle will not necessarily be unstable, although the
presence of diffuse pain in an active individual should always trigger the clinician to consider instability among the differ- ential diagnosis. Overall, the examination may be somewhat underwhelming and not impressive except for the presence of pain with palpation of the anterior osteophytes.
Imaging studies of the ankle can help to confirm the diagnosis. Plain radiographs of the ankle will show a long distal tibia anterior osteophyte and likely a dorsal talar osteo- phyte. It is unusual to need any other type of more sophisti- cated imaging to come to a definitive diagnosis. Scranton and McDermott14 described a radiographic classification with limited clinical use. The surgical treatment of the bone spurs will not be dictated or changed necessarily because of their descriptive classification, but it definitely helps to bring some uniformity and standardization when communicating among clinicians. Stage I represents a distal tibia osteophyte of less than 3 mm, stage II is an osteophyte along the distal tibia of more than 3 mm with osteochondral reaction, stage III is the presence of any tibial osteophyte along a talar osteo- phyte, and stage IV is the presence of anterior, lateral, medial, and posterior osteophyte formation with reduction of the joint space and serious arthritic changes (Table 5–1).
Surgical intervention is recommended after the failure of 6 months of conservative treatment options, which will include the use of nonsteroidal anti-inflammatory drugs, activity modifications, the use of protective devices, and even the possibility of intra-articular injection of corticoster- oids. When it is time to consider a surgical approach to AAI, the two possible techniques are open versus arthroscopic debridement.
When large osteophytes are present or several previous open debridements of the ankle joint have been attempted, it is reasonable to consider an open approach. In the case of large osteophytes, it may be just a matter of having a shorter procedure and therefore a lower level of morbidity
TABLE 5–1 Classification of Anterior Bony Impingement of the Ankle Joint According to Scranton and McDermott Grade Description
Grade I Synovial impingement: Radiographs show inflammatory reaction, up to 3-mm spur formation. Dorsiflexion stress view confirms impingement. Bright-light examination of lateral view confirms anterior soft tissue swelling.
Grade II Osteochondral reaction exostosis: Radiographs show osseous spur formation larger than 3 mm. No talar spur present. Dorsiflexion view shows impingement. MRI confirms moderate osteoblastic and chondral hyperplastic reaction.
Grade III Significant exostosis with or without fragmentation, with secondary spur formation on dorsum of talus, often with fragmentation of osteophytes.
Grade IV Pantalocrural arthritic destruction: Radiographs suggest medial, lateral, or posterior degenerative arthritic changes.
From Scranton PE, McDermott JI: Anterior tibiotalar spurs: A comparison of open versus arthroscopic de´bridement. Foot Ankle 12:125–128, 1992.
associated with the procedure. In some cases when previous open attempts have been performed, the amount of scar tissue may be quite excessive. The presence of such a mas- sive amount of scar tissue combined with some distorted anatomy may increase the chances of damage to the anterior neurovascular bundle while performing an excessive and indiscriminated resection of scar tissue. Consideration to have an arthroscopically aided open debridement is always possible. In those circumstances, the arthroscopy will be used as a dry scope with the goal of facilitating visualization to help decide on the amount of debridement to be performed and not so much to actually perform the bony resection.
Arthroscopic debridement is performed through the standard anteromedial and anterolateral portals of the ankle joint. Upon entering the joint, a limited anterior synovect- omy should be performed to improve the visualization of the anterior compartment of the ankle joint. Following that, a thorough inspection of the joint should be performed.
The anterior distal tibia osteophyte should be cleared from soft tissues prior to the use of the bur to avoid any clogging of the bur itself. A shaver should be used to clear the soft tissues and prepare the bony spur for resection. The resec- tion of the tibia osteophyte should take place from medial to lateral using the medial malleolus as a reference to decide how much resection will be necessary. Special precautions should be taken to avoid any trauma to the talar chondral surface by positioning the bur sleeve toward the talus.
Bleeding from the bone should not interfere with visualiza- tion of the joint as long as a high-pressure inflow is being used (Fig. 5–3A, B).
Most dorsal talar osteophytes will also be visualized directly with the standard scope. A partial anterior distal synovectomy can also be done to improve visualization. It is important to remember the presence of arterial branches from the dorsalis pedis artery to the talus through its neck.
The synovectomy should be limited to as minimal as possi- ble as long as visualization is reasonable to avoid distur- bance to the vascular supply of the talus. The bony debridement of the talus will take place until no bony prominences above the most anterior margin of the articu- lar portion will be present. A final check with the ankle in maximum dorsiflexion should be done to confirm the absence of contact between the distal tibia and the talus.
At least a several-millimeter gap in between the tibia and the talus is advised to be present to confirm the lack of anterior impingement (Fig. 5–3C).
Outcomes/Results for Technique
Branca et al.15 reported on 58 patients with a mean age of 28.5 years and a mean follow-up of 21.5 months. Of the 58 patients, 23 were stage II and 15 were stage I. Arthroscopic debridement was performed in all patients using a variety of instruments during the procedures. Based on a patient- administered questionnaire, preoperative and postoperative scores were compared. The outcomes were classified as 37
good, 13 fair, and 8 poor. Recurrence of impingement was seen in stages III and IV. The authors recommend proceed- ing with an arthroscopic debridement of the ankle for AAI in stages I and II and not for those situations where the oste- oarthritis present is significant and occurring throughout the ankle joint (stages III and IV).
Tol et al.16reported on 57 patients with AAI. The mean age of the patients was 36 years and the mean follow-up was 6.5 years. Patients’ outcomes were rated through use of a visual analog score and the Tegner activity score. The per- centage of good results was superior (77%) in the group that did not have diffused osteoarthritis compared with the 53%
of good results in the group with diffused osteoarthritis.
Dorsiflexion was unchanged in 37 of the 57 patients even though symptoms were improved. The group with minimum osteoarthritis did not show any recurrence of spurs. In the group with minimum osteoarthritis, half of them showed partial or complete recurrence of bone spurs. The authors hypothesized that the pain present during AAI is more likely related to the chronic synovitis present and the impingement of the soft tissues by the osteophytes. Their theory was based on the uniform presence of hypertrophic synovitis at the time of surgery and the fact that patients were still asymptomatic despite having recurrence of the osteophytes.
The results mentioned here are comparable to those reported by Coull et al.17in their series of open debridement for AAI. They reported on 27 patients with an average age of 28 years and a mean follow-up of 7.3 years. Outcome results were assessed with use of the Ogilvie-Harris score. A total of 20 patients reported to be at least 80% satisfied with their results. They also found a worse result in those patients who presented with diffuse osteoarthritis throughout the ankle joint. All patients at their latest follow-up presented with recurrence of the spurs. Two thirds of the study group had recurrence after 6.5 years of follow-up.
In summary, regarding anterior bony impingement of the ankle joint, arthroscopic debridement is the most widely accepted method of treatment. Special attention has to be paid to the diffusely arthritic ankle where the benefit from an isolated anterior debridement of the ankle joint will be very limited. Patients should be advised that it is reasonable to anticipate recurrence of the osteophytes, although not necessarily the symptoms. The surgeon should entertain the possibility of proceeding with an arthroscopically aided open debridement as part of his or her armamentarium of treatment options, especially for revision cases.
Osteochondral Lesions
It has been estimated that in the United States, 1 ankle injury occurs per 10,000 people per day.18 More specifically, most are lateral ligament ankle sprains in the United States, it has been estimated that 850,000 ankle sprains occur each year (source from the National Institute of Arthritis and Musculo- skeletal and Skin Disorders). The current incidence of OCLs in patients with residual ankle instability and undergoing lat- eral ligament reconstruction of the ankle has ranged between 41 C H A P T E R5 Ankle Arthroscopy
5% and 9%.19From studies in which an ankle arthroscopic exploration was performed to evaluate the source of pain in ankles after sustaining a lateral ligament sprain, the incidence of OCL was reported to be as high as 25%.20,21
There are many theories regarding the cause of OCLs.
The two most commonly accepted theories relate to the presence of trauma or some vascular alteration, most likely in the form of a subclinical hypercoagulable state.22 Some other theories that make reference to altered genetics, some type of family predisposition,23,24and increased bone marrow pressure25have also been entertained, although with less pop- ularity. Most likely, and still from a purely speculative point of view, the cause of OCL seems to be multifactorial where
some extrinsic features may take place (trauma) in a talus predisposed to an injury by intrinsic factors (coagulopathy).
OCL of the talus may occur in the medial or the lateral side of the talar dome. Less frequently, both sides of the dome may also be affected.26The medial lesions tend to be more posterior and less frequently associated with a history of trauma, while the lateral ones tend to be located more anteriorly and more frequently associated with a history of multiple sprains or, in some instances, even just a single incident of a severe ankle sprain of the lateral ligament complex. The medial lesions also tend to be deeper and cup shaped, suggesting a mechanism of torsional impaction.
The lateral ones are more superficial and most likely indicate
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C
FIGURE 5–3.(A) Anterior distal tibia osteophyte visualized from the medial portal. (B) Distal tibia anterior margin after arthroscopic debridement of anterior osteophyte. (C) Maximum dorsiflexion of the ankle joint with confirmation of absence of anterior ankle impingement between the distal anterior tibia and the talus.
a shear mechanism of injury. The shear component will take place between the lateral aspect of the dome of the talus and the medial aspect of the articular facet from the fibula.27
The clinical presentation of an OCL may be acute or chronic. The presentation of an acute OCL has the con- founding feature of also being associated with recent trauma, which makes the identification of an OCL more challenging.
Most of the pain at presentation will be diffusely distributed throughout the ankle, which makes it extremely difficult to have a high level of suspicion for an OCL. After several weeks of conservative treatment options, the pain may persist; this should raise the suspicion for some type of intra-articular pathology of the ankle. It is not common to have pain isolated to the ankle gutter where the OCL may be present. The patient may report some other mechanical symptoms in the form of recurrent effusions, catching, or even locking of the joint in the event of having a loose body. All those symptoms should lead the clinician toward the suspicion of having a patient presenting with an OCL of the talus.
Diagnosis
The diagnosis will start with a thorough physical examina- tion of the ankle. It is important to check for the current status of the lateral ligament complex of the ankle to assess whether any component of instability is present. The evalu- ation of ankle stability is of special importance in the chronic setting, where there may be some consideration for surgical treatment. Plain radiographs of the ankle should be obtained during the initial evaluation to look for subchondral fractures of the talus. The radiographs should also help to rule out occult fractures commonly associated with ankle sprains (lateral process of the talus, anterior process of the calcaneus, and fifth metatarsal are among the most commonly missed). Special attention to the dome of talus will help to provide an initial evaluation of the ankle and to develop a level of suspicion for talar dome pathology. If there is radiographic indication on plain radiographs of an OCL, it is still helpful to classify and determine the morphology of the lesion by CT or magnetic resonance imaging (MRI) as part of the preoperative planning. Both CT scanning and MRI of the ankle are valid studies to gather such information. The CT scan will help to better delineate the morphology of the osteochondral fragment, as well as the status of the subchondral bone surrounding the OCL. The CT is also cheaper and faster to obtain. The MRI will provide less detailed information about the morphology of the fragment, but it will help to assess the chronicity of the fragment by the presence of signal changes (especially on T2 sequences or fat suppres- sion) more compatible with acute pathology. The presence of synovial fluid at the base of the OCL will signify disrup- tion of the chondral surface and thereby help the surgeon to choose the most convenient technique to address the defect. Verhagen et al.28 evaluated 27 OCLs of the talus and compared the diagnostic value of patient’s history, physical examination, plain radiography, plain radiography
with a 4-cm heel raise, helical CT, MRI, and diagnostic arthroscopy. CT and MRI were shown to have similar diag- nostic values when it comes to assessment of size and mor- phology of OCLs of the talus.28MRI had better sensitivity than CT in the presence of a negative study.
The OCLs of the talus have been historically classified following the Berndt and Harty classification (Fig. 5–4). This classification is simple and easy to remember. It has the added advantage of truly helping to navigate through the algorithm for the treatment plan of OCLs of the talus.
Treatment
Unfortunately, the literature is not very clear when it comes to the treatment options or algorithm for acute OCLs of the talus. The large majority of the studies report on chronic injuries and very few will make reference to specifically acute OCLs.18,29For acute OCLs of the talus, conservative treat- ment has been recommended for OCLs up to a stage III for posteromedial lesions and up to a stage II for the antero- lateral ones (graded according to the Berndt-Harty classifica- tion). Conservative treatment includes the use of a protective device and non–weight-bearing of the affected extremity for a total of 6 weeks.30
For chronic OCLs, the clinician will start with a trial of conservative treatment options before proceeding with any surgical recommendations. Conservative treatment options will include the use of nonsteroidal anti-inflammatory drugs, activity modifications through avoidance of impact activities, the sensible use of corticosteroid injections, and the use of viscosupplementation via an injectable or oral route. If symp- toms persist after 6 months of conservative treatment, the clinician should consider a surgical approach as the next treatment step. The surgical options available are:
1. Arthroscopic debridement of the talus
2. Arthroscopic debridement of the talus plus microfracture and/or drilling
3. Arthroscopic debridement of the talus followed by a cartilage-replacement procedure
Takao et al.’s31 report on their series showed a statistically significant difference with a better outcome in the group of patients who underwent debridement of the OCL versus those who underwent only drilling of the OCLs. Tol et al.32reported on a meta-analysis in which perforation of the subchondral bed after excision and debridement of the lesion increased the overall percentage of good and excellent results by 10%. It is rare to find a case where the location of the defect will keep the surgeon from proceeding with a vas- cular stimulation of the defect. Through range of motion of the ankle and creation of accessory portals, access should be reasonable enough to proceed with perforation of the defect without compromising vital structures.
Arthroscopic debridement of an OCL of the talus fol- lowed by microfracture or drilling is the most common sequence of events to be performed when treating these lesions. After placement of the instruments in the ankle joint, 43 C H A P T E R5 Ankle Arthroscopy