he term “impingement” is defined in the Merriam-Webster Dictionary as “to strike or collide,” “to encroach or infringe,” or “to make an impression.”1
In the ankle, “impingement” is used to describe soft tissue and/or bony problems. Soft tissue impingement has been discussed previously in Chapter 8
. This chapter will discuss bony impingement anteriorly, posteriorly, or both. Ankle joint bony impingement is defined as a clinical syndrome that includes joint pain, limitation of motion, and/or symptoms of instability. In addition, impingement can occur secondary to loose bodies getting caught in the joint, and this will be discussed later in the chapter along with other posttraumatic problems and foreign bodies.
Ankle sprains are among the most commonly encountered orthopedic injuries accounting for the largest single number of emergency room orthopedic evaluations. Ankle sprains usually resolve completely, resulting in a joint with full range of motion and patients who return to full activities. However, in some cases involving a more severe or recurrent injury, there may be persistent pain or instability. The symptom of instability may be due to actual ligament insufficiency or it may be due to impingement that causes pain or giving way of the joint in the absence of true ligament laxity.
ANTERIOR BONY IMPINGEMENT
Anterior bony impingement (ABI) is a common cause of chronic sprain pain, especially seen in athletes. In 1943, Morris was the first to describe this condition as “athlete’s ankle.”2
Subsequently, in 1950, McMurray named it “footballer’s ankle,” which he suggested occurred after repetitive ankle sprains of relatively minor severity resulting in the development of bony spurs within the ankle joint capsule, on either the anterior tibia or the neck of the talus.3
He attributed the development of the lesion to the position of maximum plantar flexion during the process of kicking a soccer ball. He noted that the typical lesion arose just above the tibial articular margin and that the articular cartilage of the joint was normal. He postulated that these bony exostoses arose from a traction injury of the anterior joint capsule, which occurred when the foot was in extreme plantar flexion.
In contrast, O’Donoghue specifically rejected the postulate that the injury causing anterior osteophyte impingement was repetitive forced plantar flexion and instead suggested the opposite mechanism of injury.4
He proposed that anterior osteophytes formed after an ankle injury with the joint in a position of forced dorsiflexion causing direct bony impingement and the subsequent development of bony exostoses after repetitive injury (Fig. 10-1)
The hypothesis that spurs are formed by plantar flexion assumes that the capsular attachment is located at the anterior cartilage rim. However, the anterior joint capsule attaches onto the tibia on average 6 mm proximal to the joint level.5
In addition, the talar capsule attaches ˜3 mm
from the distal cartilage border. This distance from the capsular attachment to the spurs is relatively large, making the idea of recurrent traction to the joint capsule causing these spurs not plausible. This is further supported by findings at arthroscopy that show the tibial spurs distal and the talar spurs proximal to the joint capsule. These findings suggest that the osteophytes form in response to repetitive trauma rather than capsular injury.
FIGURE 10-1. Father of Sports Medicine, Don O’Donoghue.
In another study, 28 talus specimens from the San Diego Museum of Man were examined regarding the location of bony outgrowths in comparison with the talar head. The authors noted that on the medial aspect of the anterior talus, bone spur formation occurred in an intra-articular location, suggesting a true osteophyte. In contrast, on the more lateral aspect of the anterior talus, the outgrowths occurred in an extra-articular location and appear to be in response to a capsular traction injury and are termed “enthesophytes”6 (Fig. 10-2A and B)
Tol et al. studied 150 kicking actions in a group of 15 soccer players and found that hyperplantar flexion was not detected in the majority of kicking motions.7
They suggested that anterior bony impingement was probably due to recurrent impact of the ball against the anteromedial ankle and midfoot rather than hyperplantar flexion or hyperdorsiflexion. In another study of medial ankle injuries after lateral ligament injuries, van Dijk proposed that impaction injury to the medial side of the joint occurring with the ankle in an inverted and supinated position resulted in non-weight-bearing articular cartilage injury and a subsequent repair response that may result in the formation of bony spurs not associated with osteoarthritis.8
Berberian et al. studied x-rays and CT scans on 10 ankles and found that talar spurs were medial and tibial spurs were lateral to the midline. Thus, the concept of “kissing osteophytes” rarely occurs, and the pain in these ankles is not due to the osteophyte directly.9
Instead, the pain associated with ankle bony anterior osteophytes is probably secondary to the inflamed soft tissue impingement and associated synovitis in the vicinity of the bony exostosis along with the physical impingement of the bone spurs during ankle dorsiflexion.
FIGURE 10-2. Bony anatomy of the talus. (A) This is a superomedial view of a left talus bone specimen. Note the medial malleolar surface (M), talar head (H), and trochlear surface (T). Outgrowth in the medial aspect of the talus is also observed (arrow). (B) Superomedial drawing of the left talus. The flexor hallucis longus (FHL) groove is formed by the medial and lateral tubercles and the posterior surface of the talar body. The talar ridge is located at the distal part of the talar neck. FHL groove-talar head (FH) is the shortest distance from the talar head to the FHL groove. Bony spur-talar head (SH) is the shortest distance from the talar head to the bone spur (X). (Reprinted from Hayeri MR, Trudell DJ, Resnick D. Anterior ankle impingement and talar bony outgrowths: osteophyte or enthesophyte? Paleopathologic and cadaveric study with imaging correlation. AJR Am J Roentgenol 2009;193:W334-W338, with permission.)
Histopathologic analysis of the tissue removed at arthroscopy showed chronic inflammation with synovial hyperplasia and subsynovial capillary proliferation. Overall, the etiology of bony impingement is secondary to multiple causes, including degenerative joint disease, hyperdorsiflexion, microtrauma, and instability.
The typical patient with anterior bony impingement is a young athlete who participates in a sport requiring repetitive ankle dorsiflexion and plantar flexion. Symptoms include generalized anterior ankle pain often made worse with forced ankle dorsiflexion or plantar flexion. Patients may complain of ankle instability unrelated to the bony exostoses, and each patient must be evaluated to determine whether the symptom of instability is secondary to true lateral ligament laxity or is simply related to the impingement itself. Swelling may accompany weight-bearing activities.
Physical examination of the patient with a symptomatic anterior bony osteophyte reveals tenderness over the anterior tibia at the level of the joint line, sometimes with a palpable bony mass in the area. There may be a degree of associated swelling in the soft tissues due to secondary joint synovitis, and there may be limitation of ankle joint dorsiflexion along with increased discomfort with forced
dorsiflexion of the joint. It is important to perform a complete physical examination to rule out other causes of anterior ankle pain such as tenosynovitis of the tibialis anterior tendon or the common extensors. The range of motion of both the ankle joint and the subtalar joint should be assessed along with hindfoot alignment. The joint should also be assessed for clinical signs of lateral and anterior joint laxity comparing the affected joint to the opposite side normal ankle.
FIGURE 10-3. Anterior tibial osteophytes. (A) Lateral x-ray demonstrating anterior distal tibial osteophytes and small talar neck osteophytes pointing away from the joint. (B) Drawing demonstrates osteophytes along the distal tibia and talar neck as the ankle starts to dorsiflex. Rarely do true “kissing” osteophytes occur. (C) Lateral dorsiflexion x-ray demonstrating anterior osteophyte impingement in the talar neck region. (Figure B from Stoller DW. Stoller’s Atlas of Orthopaedics and Sports Medicine. Philadelphia, PA: Wolters Kluwer, 2007, with permission.)
Patients being evaluated for anterior ankle pain should have weight-bearing anteroposterior (AP), weight-bearing lateral, and mortise views of the ankle. Most anterior tibial osteophytes and talar neck osteophytes will be visible on these views (Fig. 10-3A, B)
. Sometimes, lateral x-rays should be done in maximum dorsiflexion to detect bony impingement (Fig. 10-3C)
. Care should be taken to evaluate the subtalar
joint for abnormalities such as degenerative changes, cysts, or loose bodies. The Broden view may be used to supplement the lateral ankle radiograph to evaluate the posterior subtalar joint.10
Standard weight-bearing foot radiographs should also be reviewed to eliminate the midtarsal joints as a cause of pain that the patient may identify as anterior ankle and foot discomfort.
In 1992, Scranton and McDermott proposed a radiographic classification system for anterior ankle osteophytes based upon the size of the anterior tibial osteophyte, the association with a talar osteophyte, and the presence of generalized degenerative changes in the ankle joint (Fig. 10-4
; Table 10-1)
They felt that types I, II, and III impingement could be treated arthroscopically, but type IV impingement was better treated through an open approach. Results after surgical excision of osteophytes are known to be better in the lower-grade lesions.
FIGURE 10-4. (A-D)
Scranton-McDermott Classification of anterior ankle impingement. Type I involves primarily synovial impingement and the degree of osteophytes and degenerative arthritis increases from type I to type IV. See also Table 10-1
. (From Johnson D, Amendola N, Barber F, et al. Operative arthroscopy, 4th ed. Philadelphia, PA: Wolters Kluwer Health, 2012.)
In 1997, van Dijk et al. developed a classification of osteoarthritis changes of the ankle joint, 0 through 3, that is commonly used to describe x-ray changes of osteoarthritis on patients’ x-rays (Table 10-2)
In a prospective study of 57 ankle debridement procedures, Tol et al. found improved results in patients whose preoperative radiographs showed no joint space narrowing in comparison to patients whose osteophytes were associated with joint space narrowing on plain x-rays.13
van Dijk and Tol have suggested that many of the anterior tibial osteophytes that cause anterior impingement pain are actually anteromedial rather than midtibial in location and that the extent of these lesions can be underestimated
on routine lateral radiographs.14
Tol et al. studied 60 patients with ABI and developed an oblique lateral radiograph to better delineate these lesions. They emphasized the importance of extending the resection of the lesions completely by continuing the removal along the anterior tibia and the medial malleolus during arthroscopic resection. They termed this view the “anteromedial impingement view” or AMI view (Fig. 10-5A)
. In their study, they showed that the lateral x-ray sensitivity for tibial osteophytes was 40% and for talar osteophytes 32% (Fig. 10-5B)
. With the AMI view, the sensitivity increased on tibial osteophytes to 85% and talar osteophytes to 73%15 (Fig. 10-5C)
Table 10-1. Scranton-McDermott Classification of Anterior Ankle Impingement
Synovial impingement; radiographs show inflammatory reaction with spurs as large as 3 mm
Osteochondral reaction exostosis; radiographs show osseous spur formation >3 mm but no talar spur is present
Severe exostosis with or without fragmentation, with secondary spur formation noted on the dorsum of the talus; also seen often is fragmentation of the osteophytes
Pantalocrural osteoarthritic destruction; x-rays suggest degenerative osteoarthritic changes medially, laterally, or posteriorly
From Scranton Jr PE, McDermott JE. Anterior tibiotalar spurs. a comparison of open versus arthroscopic debridement Foot Ankle 1992;13:125-129.
FIGURE 10-5. Anteromedial impingement view (AMI). (A) This oblique lateral x-ray is done to better visualize osteophytes along the anteromedial distal tibia as they extend along the medial malleolus. (B) Lateral x-ray showing minimal anterior distal tibial osteophytes.
Table 10-2. van Dijk Osteoarthritis Classification
Normal joint or subchondral sclerosis
Osteophytes without joint space narrowing
Joint space narrowing with or without osteophytes
Total disappearance or deformation of the joint space
From van Dijk CN, Tol JL, Verheyen CC. A prospective study of prognostic factors concerning the outcome of arthroscopic surgery for anterior ankle impingement. Am J Sports Med 1997;25:737-745.
The normal angle between the anterior distal tibia and talus is 60° or greater. When osteophytes form on the tibia and/or talus, they narrow the angle to <60°. It is important at surgery to reconstitute this angle to help alleviate the patient’s pain (Fig. 10-6A, B)
Computed tomography (CT) has the ability to completely delineate the extent of the osteophyte formation but is not required for most patients with osteophytes unless
it is being utilized to evaluate or rule out another type of ankle pathology. It is particularly helpful in determining if a fracture has occurred through the osteophyte, which is seen most commonly in athletes such as football and basketball players. Similarly, magnetic resonance imaging (MRI) can delineate the lesions and show fluid, bone marrow edema, and sclerosis (Fig. 10-7A, B)
. It may be most useful in assessing other concomitant issues particularly in the soft tissue structures. For example, MRI has the ability to show coexisting soft tissue impingement such as
the so-called meniscoid lesion, hypertrophy of the anterior inferior tibiofibular ligament (Bassett lesion), along with abnormalities of the adjacent ligament and tendon structures.
FIGURE 10-5. (Continued) (C) AMI view demonstrates osteophytes along the distal tibia and medial talar neck. (Figure A from Johnson D, Amendola N, Barber F, et al. Operative arthroscopy, 4th ed. Philadelphia, PA: Wolters Kluwer Health, 2012, with permission.)
FIGURE 10-6. Osteophyte formation. (A) The normal angle between the distal tibia and the talar neck should be 60° or greater. (B) The presence of osteophytes on the distal tibia or talus can narrow the angle to <60°. (Copyright Richard D. Ferkel.)
FIGURE 10-7. Anterior bony impingement. (A) Sagittal drawing showing anterior spur formation along the anterior distal tibia and talar neck (1). Capsular contraction (2) and Achilles tendon shortening (3) can be associated with this condition. (B) Sagittal T1 W1 MRI demonstrating hypointense sclerotic anterior osteophytes of the tibia and talus, contributing to anterior bony impingement. (Courtesy of David W. Stoller, MD.)
Patients with suspected anterior impingement secondary to anterior osteophyte formation may be treated nonoperatively with activity modification, anti-inflammatory medications, orthotics or shoe modifications, and judicious use of corticosteroid injections. Formal physical therapy modalities may also be utilized. Failure to improve after these measures is the indication to proceed with operative treatment.
The patient is placed in the supine position on the operating table under general or spinal anesthesia, after a popliteal block has been performed by the anesthesiologist. The hip and knee on the operative side are flexed and supported by a well-padded thigh support. The thigh support should be broad and well padded so that the force of joint distraction is spread over a wide area of the thigh rather than being concentrated in the popliteal fossa and potentially contributing to increased venous stasis in the operative extremity (Fig. 10-8)
(see Chap. 4
). This position allows the ankle to hang in a plantigrade position, allows free intraoperative motion, and allows access to both anterior and posterior portals. A thigh tourniquet is placed but only inflated if necessary during the procedure.
The noninvasive ankle distractor is applied and routine anteromedial, anterolateral, and posterolateral portals are placed using the “nick and spread” technique to minimize the risk of damage to superficial neurovascular structures (see Chap. 7
) (Fig. 10-8)
. Even though the diagnosis of anterior joint pathology is known, a comprehensive and organized full ankle joint 21-point diagnostic evaluation should be performed, as described in Chapter 7
. The joint is evaluated first from the anteromedial portal, second from the anterolateral portal, and third from the posterolateral portal.
The presence of a large anterior osteophyte along with joint synovitis may make initial joint visualization difficult. A limited anterior synovectomy should be performed
being careful to direct the shaver away from the anterior capsule to minimize the risk of capsular penetration and the potential for neurovascular injury. Improved visualization may be obtained by diminishing the joint distraction force while dorsiflexing the ankle during the anterior synovectomy and when removing the anterior osteophyte (Fig. 10-9)
. This position improves anterior visualization by relaxing the anterior capsule. An intra-articular electrosurgery device is used to achieve hemostasis during the synovectomy.
FIGURE 10-8. Arthroscopic setup in a left ankle with noninvasive distraction. The arthroscope is through the anteromedial portal, the shaver is through the anterolateral, and inflow is through the posterolateral portal.
FIGURE 10-9. Relaxing the distraction and dorsiflexing the ankle opens the anterior capsule making exposure and excision of the anterior osteophytes on the distal tibia and anterior talus easier to remove. (Illustration by Susan Brust.)
FIGURE 10-10. Removal of osteophyte with a burr. (A) Incorrect removal of osteophyte secondary to the adherent capsule to the distal tibia. (B) Residual anterior distal tibial osteophyte is present after burring because the anterior aspect of the spur is not visualized. (C) Correct method of removing an osteophyte using a shaver to peel the anterior capsule off the anterior border of the osteophyte. (Illustration by Susan Brust.)
FIGURE 10-11. Exposure of the anterior distal tibia osteophyte using a radiofrequency wand to peel the soft tissue off the osteophyte and expose it in its entirety.
The anterior joint capsule is always adherent to the anterior tibial osteophyte, and it must be stripped off its surface for exposure. Exposure of the osteophyte may be performed by using a shaver or an electrosurgery device (Figs. 10-10A-C and 10-11)
. When using the shaver, the blade must be directed toward the osteophyte and pointed away from the anterior capsule so as to avoid neurovascular injury secondary to anterior capsular penetration. The use of electrosurgery has the advantage of simultaneously achieving hemostasis during the exposure of the osteophyte.
FIGURE 10-12. An osteotome can be used to remove the anterior distal tibial osteophytes. It is critical that the osteotome be angled in the appropriate direction so as not to gouge into the normal distal tibia.
After complete exposure of the osteophyte, excision may be performed using three different methods: osteotome, burr, or rongeur. An osteotome cuts the osteophytes, and the bony fragments are removed using the loose body forceps or pituitary rongeur (Fig. 10-12)
. Alternatively, the osteophyte may be removed using a round burr from both medial and lateral approaches (Fig. 10-13A, B)
. Care must be exercised to extend the resection to the lateral margin of the tibia and syndesmosis and medially along the margin of the tibia to the tip of the medial malleolus. The rongeur can be used to remove smaller osteophytes and “fine-tune” the excision (Fig. 10-14)
The amount of bony resection performed during osteophyte excision may be difficult to determine. A good guideline is to resect anterior tibia until articular cartilage of normal thickness is achieved along the entire anterior border of the tibia. For those with less experience in ankle arthroscopy, an intraoperative lateral radiograph or fluoroscopy can be used to document adequate resection. If a lateral x-ray is not done at surgery, one should be done at the postoperative visit (Fig. 10-15A-D)
. After anterior tibial resection, the arthroscope should be directed along the talar neck to determine whether an osteophyte is present. Resection is performed as above using a round burr.
FIGURE 10-13. Excision of osteophyte by burr. (A) Removal of the anterior distal osteophyte using a motorized burr. It is important that the burr does not extend to the underlying normal articular cartilage. (B) Intraoperative picture demonstrating the use of a 4.0-mm circular burr to facilitate spur removal. (Figure A, illustration by Susan Brust.)
FIGURE 10-14. Osteophytes can also be excised with the use of a heavy-duty pituitary rongeur.
An alternative method for anterior osteophyte removal places the arthroscope in the posterolateral portal, visualizing the anterior osteophyte from posterior to anterior. Sometimes, this method makes it easier to see the junction between the osteophyte and normal cartilage by looking from the posterolateral portal. Then, the arthroscopic burr is introduced from one of the anterior portals and the amount of resection is monitored from the posterior viewing portal (Fig. 10-16)