Cartilage Lesions in Anterior Bony Impingement of the Ankle

Original Article With Video Illustration

Cartilage Lesions in Anterior Bony Impingement of the Ankle Jeong-Seok Moon, M.D., Kang Lee, M.D., Ho-Seong Lee, M.D., and Woo-Chun Lee, M.D.

Purpose: The aim of this study was to investigate the correlations between spur severity, clinical characteristics, and articular cartilage lesions in patients with anterior bony impingement. Methods: The study included 57 ankles in 57 patients (48 male and 9 female patients; age range, 15 to 59 years) who had undergone a spur resection for anterior impingement. We excluded spurs in patients with osteoarthritis with joint space narrowing. Spur severity was classified by use of the McDermott scale. The correlations between spur severity, clinical characteristics, and articular cartilage lesions were evaluated. Differences in the mean lengths of the tibial spurs were examined according to the presence or absence of tram-track lesions, spur fragmentation, and loose bodies. Results: The duration of pain, degree of sports activity, and presence of mechanical instability showed no relation to spur severity. Of the ankles, 28 (49.1%) were grade 1, 1 (1.8%) was grade 2, and 28 (49.1%) were grade 3. Cartilage lesions were present in 46 ankles (80.7%). Spur severity was correlated with the degree of cartilage lesions (Spearman ␳ ⫽ 0.30, P ⫽ .02). Grade 3 ankles had more spur fragmentation than grade 1 or 2 ankles. The mean length of the tibial spurs with tram-track lesions or spur fragmentation was longer than that without these lesions. Conclusions: The results suggest that cartilage lesions are present even in ankles with small spurs and that the degree of cartilage lesions increases as spurs become larger. Level of Evidence: Level IV, therapeutic case series.

A

nterior bony impingement (ABI) is commonly seen in the ankle joints of young persons with a high degree of sports activity.1-3 ABI can develop from repetitive supination injury in chronic ankle instability, repetitive forceful dorsiflexion movements

From the Department of Orthopaedic Surgery, Seoul Paik Hospital, College of Medicine, Inje University (J-S.M., K.L., W-C.L.); and Department of Orthopaedic Surgery, Asan Medical Center, College of Medicine, Ulsan University (H-S.L.), Seoul, South Korea. The authors report no conflict of interest. Received April 28, 2009; accepted November 25, 2009. Address correspondence and reprint requests to Woo-Chun Lee, M.D., Department of Orthopaedic Surgery, Seoul Paik Hospital, College of Medicine, Inje University, No. 85, 2-ga, Jeo-dong, Jung-Gu, Seoul 100-032, South Korea. E-mail: lwsk980@unitel .co.kr © 2010 by the Arthroscopy Association of North America 0749-8063/9256/$36.00 doi:10.1016/j.arthro.2009.11.021 Note: To access the video accompanying this report, visit the July issue of Arthroscopy at www.arthroscopyjournal.org.

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commonly seen in the athlete, or repetitive direct trauma to the anteriorly located cartilage rim of the ankle as seen in the kicking action.2,4-6 Soft-tissue and bony structures are compressed during forced ankle dorsiflexion, and this phenomenon is known to induce pain in ABI. We often find large spurs in ankles that exhibit occasional symptoms after twisting injury or strenuous exercise, and it is difficult to decide whether to recommend surgery for these spurs, which are not very disabling in everyday activities. Considering that some authors have reported that spurs with a normal joint space may be accompanied by cartilage lesions,7-9 large spurs may need to be excised to prevent cartilage lesions, and this may be true even for asymptomatic spurs. Arthroscopic or open excision for spurs without joint space narrowing leads to favorable outcomes.2,4,7,10-12 However, there is limited information on the arthroscopic findings of spurs without joint space narrowing. Furthermore, our review of the

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 26, No 7 (July), 2010: pp 984-989

ANTERIOR BONY IMPINGEMENT literature failed to find a single study that correlates the severity of spurs and degree of cartilage lesions in ABI. The aim of this study was to investigate the potential correlation between spur severity and the degree of cartilage lesions in ABI. We hypothesized that there is a correlation of the severity of spurs with the degree of cartilage lesions in ABI. METHODS The data from a clinical database were evaluated for 351 consecutive patients (364 ankles) who had undergone an arthroscopic examination for chronic ankle pain between January 2004 and January 2009. We excluded patients who had spurs with joint space narrowing, because articular cartilage lesions were obvious in these cases. Patients were also excluded if their spurs were associated with cartilage changes, including an osteochondral lesion of the talus (OCL), inflammatory arthropathy, and septic arthritis. We suspect OCL if there is a demarcated radiolucent subchondral area or subchondral fracture line is seen in the talar dome on plain radiographs. If OCL is suspected on physical examination and plain radiographs or if scintigraphy shows increased uptake, we routinely perform magnetic resonance imaging (MRI) to diagnose OCL. Typical MRI findings include an area of low signal intensity on T1-weighted images and high-signal rims that surround osteochondral fragments, often with adjacent bone marrow edema on T2-weighted images. In cases of localized subchondral trabecular compression, although the plain radiograph findings are normal, MRI of the affected area shows a decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. Cystic OCL shows a well-demarcated or poorly demarcated area of high signal intensity on T2-weighted images. Computed tomography (CT) is more useful than MRI for assessing OCL cortical demarcation. Therefore osteochondral fractures and cystic OCLs are well delineated on CT scans. We have diagnosed OCL preoperatively using the appropriate combination of the previously mentioned diagnostic tools. Consequently, 57 patients were enrolled in this study. We studied a total of 57 ankles in 57 patients (48 male and 9 female patients; mean age, 31.2 years; age range, 15 to 59 years) who had undergone arthroscopic debridement or open spur excision. The mean duration of ankle pain was 22.7 months (range, 1 to 240 months). The degree of sports activity was as follows: professional athlete (n ⫽ 4), recreational ath-

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lete (n ⫽ 31), and nonparticipant in sports (n ⫽ 22). A diagnosis of ABI was made if the patient had anterior tibial or tibiotalar spurs on plain radiographs and anterior ankle pain. The indication for surgical excision for ABI was chronic ankle pain that interfered with daily activity or work despite a minimum of 2 months of conservative treatment in the form of rest, compression, anti-inflammatory medication, and physiotherapy. Of the patients comprising the study population, 14 (24.6%) were diagnosed with chronic ankle instability and had a history of severe ankle sprain or multiple ankle sprains. The mean duration of pain after the initial sprain was 89 months (range, 8 to 288 months). We used stress radiographs if the patients described repetitive sprain episodes, felt instability, or showed a positive anterior drawer or talar tilt test. The diagnosis of chronic instability was based on stress radiographs. The anterior drawer and varus talar tilt stress radiographs were obtained by use of a jig with an applied pressure of up to 150 N. Pathologic laxity was defined as an anterior drawer value of greater than 10 mm or a side-to-side difference of greater than 3 mm or a talar tilt value of greater than 9° or a sideto-side difference of greater than 3°.13 Twelve of these patients underwent lateral ligament repair (n ⫽ 8) or reconstruction (n ⫽ 4) during spur excision. Plain anteroposterior, lateral, and mortise radiographs were obtained from all ankles before arthroscopic examination. Lateral and mortise radiographs were used for the assessment of the length of the spur and McDermott classification14 (Fig 1A). All spurs were graded by the McDermott classification: grade 1, anterior tibial spur measuring less than 3 mm; grade 2, anterior tibial spur measuring more than 3 mm; grade 3, anterior tibial spur with secondary talar spur (kissing lesion); and grade 4, panarthritis. Grade 4 spurs were excluded from this study. To assess the size of tibial spurs, the greatest length from the anterior rim of the plafond was measured in 0.5-mm increments on lateral radiographs. We did not measure talar spur length, because it is optimally visualized on mortise radiographs, and measuring the length on mortise views proved very difficult because the anatomic landmark of the spur base was obscured. The arthroscopic examination was performed by 1 senior author (W-C.L.) within 1 month after radiographic examination. The arthroscopic findings of each patient were reviewed through a multimedia database. During the review, the degree of cartilage lesion was graded by use of the Outerbridge classification.15 The tram-track lesion9 was defined as welldefined longitudinal cartilage troughs with variable

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J-S. MOON ET AL.

FIGURE 1. (A) A 24-year-old man with an anterior tibial spur and secondary talar spur corresponding to McDermott grade 3 (asterisk) on lateral radiograph. (B) Arthroscopic findings showed a defect of greater than 0.5 inch in diameter in the talar articular cartilage, with tram-track lesions involved at both the talar and tibial articular surfaces. (C) A loose body is evident in the posterior gutter of the ankle joint (arrow).

width and depth in the talar dome or plafond (Fig 1B). Tram-track lesions are believed to be a type of cartilage lesion. However, tram-track lesions are different from an OCL. The OCL of the talus is a focal lesion involving cartilage and subchondral bone, and its extent can be detected by imaging methods, whereas a tram-track lesion is usually detected only by arthroscopic examination. As such, we can differentiate between them. The relation between McDermott scale and clinical characteristics was analyzed. The correlation between spur severity, as assigned by the McDermott scale, and cartilage lesions, as determined by the Outerbridge classification, was also examined. Furthermore, the differences in cartilage lesion severity in relation to the pres-

ence or absence of loose bodies or spur fragmentation were evaluated. The correlation between the duration of instability and spur size and the correlation between the duration of instability and grade of cartilage lesion were investigated. Specific arthroscopic findings were analyzed according to the McDermott grading system. Because there was only 1 ankle with a grade 2 spur, we combined the 3 McDermott scale groups into 2 groups, to distinguish the degree of cartilage change: 1 with tibial spurs and 1 with tibiotalar spurs. The mean tibial spur length was compared based on the presence or absence of specific arthroscopic findings. This study was approved by the institutional review board at our hospital, and informed consent for the use of medical information was obtained from all patients.

ANTERIOR BONY IMPINGEMENT TABLE 1. Relation Between Spur Severity and Clinical Characteristics of 57 Patients With ABI Grade 1 Grade 2 Grade 3 Statistics P Value Age (n) ⱕ29 yr 30-39 yr ⱖ40 yr Sex (n) Male Female Duration of pain ⬍1 yr 1-5 yr ⬎5 yr Sports activity Occasional Recreational Professional Instability No Yes

13 9 6

1

17 6 5

23 5

1

24 4

15 9 2

1

18 7 2

9 17 2 19 7

1

1

13 13 2

␹2 ⫽ 5.06

.28

␹2 ⫽ 0.33

.85

␹2 ⫽ 1.11

.89

␹2 ⫽ 2.12

.71

␹2 ⫽ 0.36

.83

20 7

Statistical Analysis The correlations between the McDermott and Outerbridge grades and between the McDermott grades and duration of instability were estimated by use of the Spearman rank correlation test, which was also used to evaluate the correlations between spur size and Outerbridge grades and between spur size and duration of instability. The Mann-Whitney U test was used to evaluate the differences in severity of cartilage lesions in relation to the presence or absence of a loose body or spur fragmentation. The ␹2 test was used to examine the correlation between the spur and specific arthroscopic findings. We used the Student t test to compare the mean tibial spur lengths according to the specific arthroscopic findings. A 2-tailed P value ⱕ .05 was considered to be statistically significant in all analyses. All statistical analyses were performed with MedCalc software (version 10.0.2.0; MedCalc, Mariakerke, Belgium).

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ankles (80.7%); these were mainly located in the anterior half of the talar dome, corresponding to the mediolateral location of the tibial spurs. Most of the talar cartilage lesions showed variable sized longitudinal cartilage fibrillation or defects without involvement of the medial and lateral surfaces of the malleolus (Video 1, available at www.arthroscopyjournal.org). Tramtrack lesions were found in 18 ankles (31.6%). The mediolateral location of the talar tram-track lesions also coincided with that of the tibial spurs. Of all the ankles with tram-track lesions, 11 (61.1%) showed tram-track lesions at both the tibial and talar articular surface (Fig 1B), and these lesion were accompanied by loose bodies within the ankle joint (Fig 1C). The correlation between spur severity, as assessed by the McDermott scale, and cartilage lesions, as assessed with the Outerbridge scale, was statistically significant (Spearman ␳ ⫽ 0.30, P ⫽ .02) (Table 2). Of the 14 patients with chronic instability, 9 showed cartilage lesions. Of those ankles, 4 had ill-defined localized cartilage lesions on the medial talar dome without involvement of the anterior surface of the talar cartilage. Another four ankles had variable sized longitudinal cartilage fibrillation or defects located in the anterior half of the talar dome. The remaining ankle showed cartilage lesions located at the medial talar dome and anterior surface of talar cartilage. The mean Outerbridge grades with and without a loose body were 3.14 (SD, 0.78) and 1.67 (SD, 1.30), respectively. The difference in cartilage lesion severity with or without loose bodies was significant (P ⬍ .01), and the difference was also significant for grade 1 or 2 ankles (P ⬍ .01). The mean Outerbridge grades with and without spur fragmentation were 2.06 (SD, 1.20) and 2.03 (SD, 1.42), respectively. The difference in cartilage lesion severity with or without spur fragmentation was not significant (P ⫽ .97), and for grade 1 or 2 ankles, this difference was also not significant (P ⫽ .35). McDermott grade 3 ankles showed more TABLE 2. Distribution of Outerbridge Grades of Arthroscopic Cartilage Lesions According to McDermott Radiographic Spur Grades in 57 Patients With ABI

RESULTS The relation between the McDermott scale and clinical characteristics is shown in Table 1. The duration of pain, degree of sports activity, and presence of instability showed no relation to spur severity. According to the McDermott scale, 28 ankles (49.1%) were grade 1, 1 (1.8%) was grade 2, and 28 (49.1%) were grade 3. Cartilage lesions were present in 46

Outerbridge Grade

McDermott grade 1 2 3 Total

0

1

2

3

4

Total

10 0 1 11

3 0 4 7

7 1 10 18

4 0 7 11

4 0 6 10

28 1 28 57

988 TABLE 3.

J-S. MOON ET AL. Relation Between Spur Groups and Three Specific Arthroscopic Findings

Tram-track lesions No Yes Spur fragmentation No Yes Loose bodies No Yes

Grades 1 and 2*

Grade 3

23 6

16 12

24 5

16 12

24 5

19 9

Statistics

P Value

␹2 ⫽ 3.24

.07

␹2 ⫽ 4.47

.04

␹2 ⫽ 1.71

.19

*Because there was only 1 case of grade 2, grade 2 was incorporated into grade 1 for simplification so that one group includes tibial spurs and the other group includes tibiotalar spurs.

spur fragmentation than grade 1 or 2 ankles (Table 3). The mean tibial spur length with tram-track lesions or spur fragmentation was longer than that without these lesions (Table 4). The duration of instability was not correlated with tibial spur size (Spearman ␳ ⫽ 0.04, P ⫽ .90) or cartilage lesion grade (Spearman ␳ ⫽ 0.06, P ⫽ .85). DISCUSSION It has been suggested that anterior spurs of the ankle are associated with cartilage lesions.7,9,10 Although arthroscopic findings for ABI have been documented, there is no report regarding the correlation of spur severity with the degree of cartilage lesions in ABI. We used plain lateral and mortise radiographs to assess spur severity,7,14,16 because talar spurs are often not visualized on lateral radiographs. Although 3dimensional CT has proved to be an excellent tool to clarify the shape and size of spurs,17 we believe that plain radiography remains a valuable tool for assessments of spur grade and size. Previous studies showed that the incidence of grade 2 spurs according to the McDermott scale ranged from 4.8% to 56.3%.4,7,14,17 In contrast, our series showed only 1 ankle with a grade 2 spur (1.8%). The reason for this discrepancy may be that we found more talar spurs on mortise radiographs. Studies reporting on the arthroscopic findings of ABI are uncommon.7-9 In the literature there are reports of chondral lesions in some cases of anterior impingement syndrome, although chondral lesion severity was not analyzed. To our knowledge, our study is the first to correlate spur severity with cartilage lesions in ABI. Our series excluded ankles with joint

space narrowing, OCL, and diseases that could be associated with cartilage lesions. Therefore we consider that the cause of cartilage changes seen in this study can be more strongly attributed to ankle spurs. In this study most of the cartilage lesions were located in the anterior half of the talar dome, corresponding to a mediolateral location of tibial spurs. Direct injury caused by a spur to the talar cartilage during forward displacement of the talus with plantar flexion could be 1 of the reasons for cartilage degeneration associated with tibial spurs. The tram-track lesions clearly show this injury mechanism,18 which may be more applicable to ankles with anterior instability. Considering that one-fourth of our subjects had chronic ankle instability, cartilage lesions caused by chronic instability should be considered. Chronic ankle instability is associated with cartilage lesions, as well as with ABI.1,11,19,20 Moreover, a longer duration of instability leads to more advanced osteoarthritic changes.19,20 In our study the cartilage lesions in spurs with chronic instability consist of 2 different findings. One is cartilage lesions seen with spurs alone. The other is cartilage lesions localized to the medial talar dome. The cartilage damage observed in spurs with chronic instability may be due to anterior subluxation and varus tilt of the talus. Anterior subluxation may lead to cartilage damage, similar to that commonly seen with spurs, and varus instability may lead to localized cartilage lesions on the medial talar dome. We could not show a correlation between duration of instability and spur size or between duration of instability and grade of cartilage lesion. This may be because of the low number of unstable cases or the nonstandard distribution of instability duration. A positive correlation was found between the Outerbridge grades and the McDermott grades. Although TABLE 4. Comparison of Mean Tibial Spur Length According to Absence or Presence of Three Specific Arthroscopic Findings Variables Tram-track lesions No Yes Spur fragmentation No Yes Loose bodies No Yes *Student t test.

n

Mean ⫾ SD

39 18

3.0 ⫾ 1.6 4.9 ⫾ 2.5

40 17

2.9 ⫾ 1.7 5.3 ⫾ 2.0

43 14

3.3 ⫾ 1.8 4.6 ⫾ 2.5

P Value* .01 ⬍.001 .07

ANTERIOR BONY IMPINGEMENT there was no follow-up study showing progression of spurs from grade 2 to grade 3, cartilage lesions and abnormal arthroscopic findings observed for grade 3 indirectly suggest that it is a more advanced stage of spur formation. In this study loose bodies were found in 24.6% of ABI cases (14 of 57) and showed traumatic damage to both the talar and tibial articular surfaces. Approximately 30% of loose bodies appeared in combination with spur fragmentation. Although we do not fully understand the mechanism for loose body formation, it appears, in some instances, to result from spur fragmentation. Furthermore, loose bodies and fragments still attached to the spur are causes of cartilage lesions, as shown in this study. Although we have not performed a follow up of the outcomes for untreated spurs, it is recommended that a symptomatic large spur or a spur with a loose body or fragment should be removed, to prevent traumatic cartilage damage to the ankle joint. The major limitation of our study is the possibility of an error of measurement of spur size. Because the length of the spur was measured on lateral radiographs, the actual size of the spur might be different. We think that the correlation of the findings of 3dimensional CT with the arthroscopic findings may be helpful to resolve this limitation. However, measurement on CT was not used for analysis of spurs in this study because we have performed 3-dimensional CT only in recent cases. Future study correlating CT findings and cartilage degeneration would provide more information.

2. 3. 4.

5. 6. 7. 8. 9. 10.

11. 12. 13. 14. 15. 16.

CONCLUSIONS

17.

The results of this study suggest that cartilage lesions are present even in ankles with small spurs and that the degree of cartilage lesions increases as spurs become larger.

18. 19.

REFERENCES 20. 1. Scranton PE Jr, McDermott JE, Rojers JV. The relationship between chronic ankle instability and variations in mortise

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