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Lateral Impact Injury
HIP ARTHROSCOPY
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LATERAL IMPACT INJURY A Source of Occult Hip Pathology J. W. Thomas Byrd, MD
Arthroscopic surgery of the hip is a well-established technique. Arthroscopic inspection has identified many elusive sources of hip pathology. Consequently, there is an increasing awareness of various intraarticular lesions which can cause mechanical hip pain. These conditions can be developmental or acquired from disease or trauma. Traumatic hip injuries are usually associated with an incident of considerable magnitude with either dislocation or fracture. Residual injury is most clearly evident when reduction of the joint is incomplete or intraarticular fragments are retained. In the absence of radiographic findings and in the absence of a history of substantial hip injury, the diagnosis of traumatic hip pathology is often clouded. Significant intraarticular damage can occur as a result of seemingly minor trauma (e.g., a twisting injury). Sources of persistent mechanical hip symptoms include injury to the labrum, the articular surface, or the ligamentum t e r e ~ . ~ Before , the use of arthroscopy, these injuries were recorded only as case reports.', 2* 7* 8* 9* 15, l7 The reason has been that, in the absence of a clearly definable lesion, exploratory arthrotomy was recommended rarely. Arthroscopy of the hip has allowed clarification of the existence and nature of these lesions and a beginning for understanding the epidemiology.12Armed with an awareness of their existence, investigative techniques are becoming better at discerning intra-articular lesions.
From the Nashville Sports Medicine & Orthopaedic Center; and the Department of Orthopaedics and Rehabilitation, Vanderbilt University School of Medicine, Nashville, Tennessee ______
______
~~
CLINICS IN SPORTS MEDICINE VOLUME 20 * NUMBER 4 * OCTOBER 2001
801
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Gadolinium arthrography in conjunction with magnetic resonance (MR) imaging is currently in the forefront of this investigation.6, The surgeon must still rely on basic clinical skills, however, including the history and examination of the patient. The knowledge gained through arthroscopy helps to enhance these clinical interpretive skills. This article reports four case examples. These illustrate a clinical entity, including a specific mechanism of injury (Fig. 1);generic physical findings; the variable nature of the diagnostic work-up; and a consistent pattern of arthroscopic findings. Contact and collision sports represent a fertile ground for encountering this entity. All arthroscopic hip procedures are recorded on video and the patients are prospectively followed, using a modified Harris hip score obtained preoperatively and then postoperatively at 1, 3, 6, 12, and 24 months4 Occasionally, trends are noted, or sub-populations identified, that demonstrate characteristic features. Four such cases with 2-year follow-up are reported.
\ Figure 1. Fall results in direct blow to the greater trochanter with intact bony structure the force generated is transferred unchecked to the hip joint. (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
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CASE REPORTS Case 1
A 20-year-old male division I collegiate basketball player (height 6'5", weight 195 pounds) sustained an injury to his left hip when he was undercut on the basketball court and landed directly on the lateral aspect of the left hip. He developed anterior groin symptoms, which were treated as a "groin pull." Using a thigh wrap, anti-inflammatory medications, and various therapeutic modalities, he was able to complete the remaining 2 months of the season. Radiographs were normal (Fig. 2A). Because of persistent symptoms, a bone scan was performed and showed increased activity in the left hip (Fig. 2B). MR imaging demonstrated atypical signal changes in the medial aspect of the femoral head (Fig. 2C). The MR findings were unchanged on two subsequent studies performed over the ensuing 6 months. His symptoms remained unchanged despite a prolonged period of rest, and he subsequently was referred for further assessment. He could continue to play basketball, but his jumping ability was limited secondary to pain. Examination revealed a normal gait and full range of motion. Pain could be elicited with extremes of flexion combined with internal rotation, and abduction combined with external rotation. There was an associated slight audible pop that could not be attributed to the iliopsoas tendon. His Harris hip score was 81. With evidence of mechanical hip pain, unresponsive to an appropriate trial of conservative measures, arthroscopy was proposed for diagnostic and possibly therapeutic purposes. Arthroscopy revealed an unstable Grade IV chondral fragment off the medial aspect of the femoral head, just above the fovea capitis (Fig. 20). Excision of the unstable fragment was performed (Fig. 2E). The procedure was performed 1 month prior to the beginning of formal collegiate basketball practice. He was able to return to his preinjury level of performance, attaining league MVP and leading scorer honors for the season. His Harris hip score at 2-year follow-up was 100. Case 2
An 18-year-old male (height 6'2", weight 180 pounds) sustained a direct blow to the lateral aspect of his left hip when he was knocked down on an asphalt surface. He developed acute onset of left hip pain sufficient to warrant evaluation in an emergency room. Radiographs were normal (Fig. 3A). He had persistent pain with ambulation, requiring the intermittent use of crutches. MR imaging performed 2 months post-injury was normal. Four months post-injury, a bone scan revealed increased activity in the left hip and repeat MR imaging revealed an effusion (Fig. 3B and C). The
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Figure 2. A, AP radiograph, left hip, unremarkable. B, Radionuclide scan reveals increased activity in the left hip. C,MR image reveals extensive signal changes in the medial aspect of the femoral head characterizing subchondral injury. Illustration continued on opposite page
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Figure 2 (Continued). D, A full-thickness chondralflap lesion (asterisk) is identified at arthroscopy. €, Excision of the fragment leaves exposed subchondral bone. (A From Byrd, JWT: Labral lesions: An elusive source of hip pain. Case reports and review of the literature. Arthroscopy 12:603-612,1996; B-€ from Byrd JWT: Indications and Contraindications In Operative Hip Arthroscopy, New York, Thieme; with permission.) (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
referring physician suspected labral damage or loose bodies, and an arthrogram performed in conjunction with computed tomography (CT) demonstrated loose bodies in the joint (Fig. 30). Referral then was made for arthroscopy to remove the fragments. Referral was delayed, however, because of difficulty obtaining approval from the third-party payor. The evaluation was finally performed 14 months following the initial injury. Examination revealed an antalgic gait. Groin pain was produced just by logrolling the hip back and forth. Range of motion was limited secondary to guarding and pain, even with passive maneuvers. His Harris hip score was 60. Repeat radiographs now showed significant secondary bony changes compared to his initial films (Fig. 3E). Arthroscopy revealed two large loose bodies originating from a
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Figure 3. A, AP radiograph left hip unremarkable. B,Radionuclide scan reveals increased activity, left hip. C,MR image remarkable for pronounced asymmetric effusion, left hip. D, CT coronal reconstruction demonstrates loose bodies. Illustration continued on opposite page
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Figure 3 (Continued). f, Follow-up radiograph 13 months post injury reveals secondary changes with superolateral osteophyte formation on the femoral head. F; Loose bodies are evident (asterisk) originating from the acetabulum. Scoring of the femoral head is also evident (arrow) due to third body wear. (From Byrd JWT: Arthroscopy of Select Hip Lesions in Operative Hip Arthroscopy. New York, Thieme; with permission.) (Figures A, B, 0,€, F Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
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crater in the weight bearing portion of the acetabulum, just above the acetabular fossa (Fig. 3F). Significant secondary scoring of the femoral head also was identified due to third body wear. The loose bodies were removed with significant symptomatic improvement. His Harris hip score at 2-year follow-up was 100. Case 3
A 26-year-old male (height 6'3", weight 183 pounds) was referred for evaluation of persistent mechanical left hip pain 13 months following a fall into an empty swimming pool, when he landed on his left side. Examination revealed a normal gait and full passive range of motion of the hip. Logrolling produced mild symptoms. Anterior groin pain was most accentuated with extremes of flexion combined with internal rotation, and abduction combined with external rotation. His Harris hip score was 63. Radiographs were normal. Additionally, a bone scan and MR imaging were performed, and were normal. A fluoroscopically guided intra-articular injection of Bupivacaine temporarily alleviated his symptoms (Fig. 4A). Because of the duration and magnitude of his symptoms, failure of response to conservative measures and temporary relief from an intraarticular injection, arthroscopy of the hip was proposed. Arthroscopy revealed a Grade I11 chondral lesion in the weight bearing portion of the acetabulum, immediately above the acetabular fossa (Fig. 4B). Chondroplasty of this surface was performed with a full radius resector. Subjectively, he did not feel that he experienced much benefit from the arthroscopic procedure. His Harris hip score at 2-year follow-up was 66. Case 4
A 20-year-old division I collegiate wide receiver (height 6'2", weight 175 pounds) was referred for assessment of persistent left hip pain following an injury during spring drills. He described a twisting-lateral impact injury while being tackled. It was painful enough to require crutches for ambulation for 1 week. Since then, he had been unable to resume workouts because his hip pain worseued with activities. Radiographs and MR imaging were normal (Fig. 5A). Examination revealed a normal gait. Groin pain was produced with logrolling the hip, especially internally. Pain was accentuated with extremes of both internal and external rotation with the hip in the 90" flexed position. A painful pop also was elicited when bringing the hip from flexion to extension with neutral rotation. Range of motion was decreased only slightly. His Harris hip score was 65. A fluoroscopically guided intra-articular injection of Bupivacaine provided temporary complete alleviation of his symptoms.
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Figure 4. A, AP radiograph of left hip unremarkable. 6, Grade 111 articular fragmentation (arrows) at the medial aspect of superior weightbearing surface of the acetabulum is evident immediately above the acetabular fossa (AF). (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
Because of the magnitude and duration of his symptoms, and because they were unresponsive to conservative measures and temporarily alleviated with an injection, arthroscopy was proposed and performed 7 months following his initial injury. The principal finding was Grade I11 chondromalacia of the weightbearing portion of the acetabulum, immediately above the acetabular fossa (Fig. 5B). Chondroplasty of this area was performed with significant symptomatic improvement. His Harris hip score at 2-year follow-up was 100.
RESULTS (Table 1) This population consists of four males with an average age of 21 years (range 19 to 26 years). The left hip was involved in all cases. A consistent lateral impact mechanism of injury was described,
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Figure 5. A, AP radiograph of left hip unremarkable. B, Grade 111 articular damage, superior medial acetabulum (arrows) immediately above the acetabular fossa (AF). (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
generated by a blow to the greater trochanter from a fall. In each case, the onset of symptoms was immediate and nondisabling, but significant enough to seek medical attention. Initial radiographs were normal in all cases. Bone scan performed in three cases was positive in two. MR imaging, performed in all four cases, revealed signal changes in the femoral head in the one case of femoral articular surface involvement and eventually showed an effusion in the case with acetabular free fragments. It did not accurately define or predict the nature of the intra-articular pathology, however. In the two cases with normal MR imaging findings, symptoms were alleviated temporarily with a fluoroscopically guided intra-articular injection of Bupivacaine. CT scan defined the lesions in the one case of loose bodies. The duration of symptoms prior to arthroscopy averaged 11months (range 7 to 17 months). Arthroscopy defined the extent of intra-articular pathology in each
=
not done
Normal
20
4
N/A
Normal
Normal
15
26
3
7
Normal
Normal
14
19
2
N/A
Normal
+ +
Femoral head signal changes Effusion
Normal
4
20
Bone Scan
MR Imaging
X-rays
1
Duration of Symptoms (months)
Age (years)
Case No.
Table 1
N/A
+ +
N/A
+ N/A
N/A
Injection
N/A
CT
Grade IV chondral injury, femoral head Acetabular osteochondral loose bodies Grade I11 chondromalacia acetabulum Grade I11 chondromalacia acetabulum
Arthroscopic Findings
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case. The pattern of chondral damage was consistent with the mechanism of injury. In one case, a Grade IV chondral lesion occurred on the medial aspect of the femoral head. The three lesions on the acetabular side occurred at the medial aspect of the weightbearing surface, above the acetabular fossa. The magnitude varied with two Grade I11 chondral lesions and one case with osteochondral loose bodies. Three of four patients demonstrated significant improvement with an average preoperative score of 69 compared to 100 at 2-year follow-up. The one poor result (63 preoperative; 66 at 2-year follow-up) occurred in a worker’s compensation case. DISCUSSION
Three nonosseous structures that can be injured and thus produce an elusive cause of mechanical hip pain are the labrum, the articular surface, and the ligamentum teres. Although this paper focuses on articular injuries, a brief synopsis of the other two is worthwhile. Labral injuries were first described when they created a block to reduction of a dislocated hip.7*l5 Subsequently, isolated pathology of the labrum as a source of hip pain was described by Altenberg.’ More recently, the labrum has gained considerable attention through arthroscopy.3,l 3 Labral lesions can occur as a consequence of relatively minor hip trauma, usually a twisting injury. Rupture of the ligamentum teres is likely with a dislocation of the hip. There have been a few case reports of ligament rupture without dislocation.2,8, Villar has classified injuries to the ligamentum teres, including degenerate ligament injuries in association with degenerative disease of the joint.” Chondral injury is a reported and well-accepted indication for hip arthro~copy.~,Little has been written about isolated articular surface injuries in the hip, however. Most chondral damage is associated either with disease or as a remote consequence of previous injury resulting in a post-traumatic degenerative process. This report is the first to focus on acute chondral injuries. The mechanism of injury is often readily discerned from the history. The arthroscopic findings support this lateral impact mechanism. The observation that this injury occurred in physically fit young adult males reflects the following features. The greater trochanter is a relatively subcutaneous structure with little soft tissue absorption of the force generated by the blow. With high bone density, impact on this area is then transferred unchecked to the joint surface. Maximal bone density is achieved in the third decade of life. Perhaps with reduced bone density, either from age or disease, failure would occur through the bone with resultant fracture rather than chondral damage. Conversely, with skeletal immaturity, failure may occur through the physeal plate. The Grade IV chondral injury on the femoral surface represents
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failure at the tide mark, probably due to shear force. The acetabular lesions have the appearance of chondromalacia, probably due to chondrocyte cell death from excessive compression. In the most extreme example, injury extended into the subchondral plate with accompanying osteocyte demise and resultant osteochondral fragments. The onset of symptoms is immediate, although perhaps not disabling. Persistent dysfunction ensues, which eventually will lead to a more extensive diagnostic work-up. The physical findings are often nonspecific for the nature of intraarticular damage. Intermittent catching, as opposed to just pain, suggests an unstable fragment. Several examination maneuvers have been described, attempting to differentiate various forms of intra-articular injury.14Thus far, we have not found any of these to be reliable. Pain with logrolling the extremity back and forth is the most specific finding for an intra-articular problem, although less sensitive for subtle symptoms. More provocative tests include flexion combined with internal rotation, or abduction combined with external rotation. Both maneuvers can cause mild discomfort normally and need to be compared to the uninvolved hip. Hip symptoms usually are referred to the anterior groin, but can be deep lateral or even posterior. Although the technology is improving, investigative studies may not precisely define a chondral injury. Often indirect or nonspecific findings will suggest that a hip injury has occurred. In the presence of a negative work-up, a fluoroscopically guided intra-articular injection of anesthetic is the most reliable test to localize that the source of the symptoms is intra-articular. In my experience, MR imaging has been unreliable in discerning either bony or cartilaginous loose bodies. CT scans are quite good at showing bony fragments, and arthrography combined with CT techniques usually will show even radiolucent loose bodies. Gadolinium arthrography combined with MR imaging is currently the most promising study. This incorporates many of the best features of these other methods, and the injection may include Bupivacaine to monitor subjective response. Cases 1 and 2 bear special discussion. In Case 1, the long-term prognosis is especially concerning due to the exposed subchondral bone left after excising the chondral fragment. Due to the mechanism of injury, the lesion is on the medial aspect of the femoral head; perhaps this may improve the prognosis, modestly because it does not involve much of the superior surface, which carries most of the weightbearing force. It is suspected that the long-term prognosis will be dictated by the uncertain natural history of the signal changes evident in the femoral head on MR imaging. No further studies have been obtained, as the symptoms have not warranted this. Case 2 highlights the observation of Epstein that retained intraarticular loose bodies in the hip accelerate secondary damage.'O Radiographically, this patient demonstrated secondary changes by the time of arthroscopic intervention. Arthroscopy defined scoring of the femoral
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head directly attributable to the loose bodies. The delay in treatment was principally due to initial failure of insurance to approve the procedure. This circumstance should become less of an issue as the fundamental merits of hip arthroscopy are better recognized. SUMMARY
Arthroscopy has helped greatly in understanding the nature of many intra-articular disorders of the hip. It also has provided a better understanding of the pathomechanics and natural progression. This knowledge has aided in improving interpretative clinical skills and investigative techniques. Isolated traumatic chondral injury can occur as a result of impact loading over the greater trochanter. There seems to be a particular propensity for this injury in young physically fit adult males apt to incur this type of blow as a consequence of sport or activity. Initially, this injury may appear innocuous with variable dysfunction. When present, arthroscopy can reliably discern the pathology and often result in significant symptomatic improvement. The long-term consequences of these lesions are still concerning. Although symptomatic improvement from arthroscopic intervention is encouraging, for some cases the long-term influence may only be the knowledge provided for counseling the patient. Nonetheless, arthroscopy can be valuable in both the assessment and management of chondral injuries. References 1. Altenberg AR: Acetabular labrum tears: A cause of hip pain and degenerative arthritis. South Med J 70(2):174-175, 1977 2. Barrett IR, Goldberg JA: Avulsion fracture of the ligamentum teres in a child. A case report. J Bone Joint Surg (Am) 71:438-439, 1989 3. Byrd JWT Labral lesions: An elusive source of hip pain. Case reports and review of the literature. Arthroscopy 12(5):603412, 1996 4. Byrd JWT, Jones K S Prospective analysis of hip arthroscopy. Arthroscopy 16(6):578587, 2000 5. Byrd JWT Hip arthroscopy: The supine position. In McGinty J, Caspari R, Jackson R, et a1 (eds): Operative Arthroscopy, ed 2. New York, Raven Press, 1995, pp 1091-1099 6. Czemy C, Hofmann S, Neuhold A, et al: Lesions of the acetabular labrum: Accuracy of MR imaging and MR arthrography in detection and staging. Radiology 200:225230, 1996 7. Dameron TB: Bucket-handle tear of acetabular labrum accompanying posterior dislocation of the hip. J Bone Joint Surg 41A(1):131-134,1959 8. Delcamp DD, Klaaren HE, Pompe-van Meerfervoot HF: Traumatic avulsion of the ligamentum teres without dislocation of the hip. Two case reports. J Bone Joint Surg 7093S935, 1988 9. Ebrahim NA, Salvolaine ER, Fenton PJ, et al. Calcified ligamentum teres mimicking entrapped intraarticular bony fragments in a patient with acetabular fracture. J Orthop Trauma 5(3):376-378, 1991
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10. Epstein HC: Posterior fracture-dislocations of the hip, long term follow up. J Bone Joint Surg 56A(6):1103-1127, 1974 11. Gray AJR, Villar RN: The ligamentum teres of the hip: An arthroscopic classification of its pathology. Arthroscopy 13(5):575-578, 1997 12. Keene GS, Villar RN: Arthroscopic anatomy of the hip: An in vivo study. Arthroscopy 10(4):392-399, 1994 13. Lage LA, Pate1 JV,Villar RN: The acetabular labral tear; an arthroscopic classification. Arthroscopy 12(3):269-272, 1996 14. McCarthy JC, Day B, Busconi B: Hip arthroscopy: Applications and technique. J Am Acad of Orthop Surg 3(3):115-122, 1995 15. Paterson I: The tom acetabular labrum: A block to reduction of a dislocated hip. J Bone Joint Surg 398(2):306-309, 1957 16. Petersilge CA, Haque MA, Petersilge WJ, et al: Acetabular labral tears: Evaluation with MR arthrography. Radiology 200231-235,1996 17. Rashleigh-Belcher HJC, Cannon SR Recurrent dislocation of the hip with a ”BankartType” lesion. J Bone Joint Surg 688(3):398-399, 1986 18. Sampson TG, Glick J M Indications and surgical treatment of hip pathology. In McGinty J, Caspari R, Jackson R, et a1 (eds): Operative Arthroscopy, ed 2. New York, Raven Press, 1995, pp 1067-1078.
Address reprint requests to J. W. Thomas Byrd, MD, Nashville Sports Medicine & Orthopaedic Center 2011 Church Street, Suite 100 Nashville, TN 37203 e-mail [email protected]
0278-5919/01 $15.00
+
.OO
LATERAL IMPACT INJURY A Source of Occult Hip Pathology J. W. Thomas Byrd, MD
Arthroscopic surgery of the hip is a well-established technique. Arthroscopic inspection has identified many elusive sources of hip pathology. Consequently, there is an increasing awareness of various intraarticular lesions which can cause mechanical hip pain. These conditions can be developmental or acquired from disease or trauma. Traumatic hip injuries are usually associated with an incident of considerable magnitude with either dislocation or fracture. Residual injury is most clearly evident when reduction of the joint is incomplete or intraarticular fragments are retained. In the absence of radiographic findings and in the absence of a history of substantial hip injury, the diagnosis of traumatic hip pathology is often clouded. Significant intraarticular damage can occur as a result of seemingly minor trauma (e.g., a twisting injury). Sources of persistent mechanical hip symptoms include injury to the labrum, the articular surface, or the ligamentum t e r e ~ . ~ Before , the use of arthroscopy, these injuries were recorded only as case reports.', 2* 7* 8* 9* 15, l7 The reason has been that, in the absence of a clearly definable lesion, exploratory arthrotomy was recommended rarely. Arthroscopy of the hip has allowed clarification of the existence and nature of these lesions and a beginning for understanding the epidemiology.12Armed with an awareness of their existence, investigative techniques are becoming better at discerning intra-articular lesions.
From the Nashville Sports Medicine & Orthopaedic Center; and the Department of Orthopaedics and Rehabilitation, Vanderbilt University School of Medicine, Nashville, Tennessee ______
______
~~
CLINICS IN SPORTS MEDICINE VOLUME 20 * NUMBER 4 * OCTOBER 2001
801
802
BYRD
Gadolinium arthrography in conjunction with magnetic resonance (MR) imaging is currently in the forefront of this investigation.6, The surgeon must still rely on basic clinical skills, however, including the history and examination of the patient. The knowledge gained through arthroscopy helps to enhance these clinical interpretive skills. This article reports four case examples. These illustrate a clinical entity, including a specific mechanism of injury (Fig. 1);generic physical findings; the variable nature of the diagnostic work-up; and a consistent pattern of arthroscopic findings. Contact and collision sports represent a fertile ground for encountering this entity. All arthroscopic hip procedures are recorded on video and the patients are prospectively followed, using a modified Harris hip score obtained preoperatively and then postoperatively at 1, 3, 6, 12, and 24 months4 Occasionally, trends are noted, or sub-populations identified, that demonstrate characteristic features. Four such cases with 2-year follow-up are reported.
\ Figure 1. Fall results in direct blow to the greater trochanter with intact bony structure the force generated is transferred unchecked to the hip joint. (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
LATERAL IMPACT INJURY
803
CASE REPORTS Case 1
A 20-year-old male division I collegiate basketball player (height 6'5", weight 195 pounds) sustained an injury to his left hip when he was undercut on the basketball court and landed directly on the lateral aspect of the left hip. He developed anterior groin symptoms, which were treated as a "groin pull." Using a thigh wrap, anti-inflammatory medications, and various therapeutic modalities, he was able to complete the remaining 2 months of the season. Radiographs were normal (Fig. 2A). Because of persistent symptoms, a bone scan was performed and showed increased activity in the left hip (Fig. 2B). MR imaging demonstrated atypical signal changes in the medial aspect of the femoral head (Fig. 2C). The MR findings were unchanged on two subsequent studies performed over the ensuing 6 months. His symptoms remained unchanged despite a prolonged period of rest, and he subsequently was referred for further assessment. He could continue to play basketball, but his jumping ability was limited secondary to pain. Examination revealed a normal gait and full range of motion. Pain could be elicited with extremes of flexion combined with internal rotation, and abduction combined with external rotation. There was an associated slight audible pop that could not be attributed to the iliopsoas tendon. His Harris hip score was 81. With evidence of mechanical hip pain, unresponsive to an appropriate trial of conservative measures, arthroscopy was proposed for diagnostic and possibly therapeutic purposes. Arthroscopy revealed an unstable Grade IV chondral fragment off the medial aspect of the femoral head, just above the fovea capitis (Fig. 20). Excision of the unstable fragment was performed (Fig. 2E). The procedure was performed 1 month prior to the beginning of formal collegiate basketball practice. He was able to return to his preinjury level of performance, attaining league MVP and leading scorer honors for the season. His Harris hip score at 2-year follow-up was 100. Case 2
An 18-year-old male (height 6'2", weight 180 pounds) sustained a direct blow to the lateral aspect of his left hip when he was knocked down on an asphalt surface. He developed acute onset of left hip pain sufficient to warrant evaluation in an emergency room. Radiographs were normal (Fig. 3A). He had persistent pain with ambulation, requiring the intermittent use of crutches. MR imaging performed 2 months post-injury was normal. Four months post-injury, a bone scan revealed increased activity in the left hip and repeat MR imaging revealed an effusion (Fig. 3B and C). The
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Figure 2. A, AP radiograph, left hip, unremarkable. B, Radionuclide scan reveals increased activity in the left hip. C,MR image reveals extensive signal changes in the medial aspect of the femoral head characterizing subchondral injury. Illustration continued on opposite page
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Figure 2 (Continued). D, A full-thickness chondralflap lesion (asterisk) is identified at arthroscopy. €, Excision of the fragment leaves exposed subchondral bone. (A From Byrd, JWT: Labral lesions: An elusive source of hip pain. Case reports and review of the literature. Arthroscopy 12:603-612,1996; B-€ from Byrd JWT: Indications and Contraindications In Operative Hip Arthroscopy, New York, Thieme; with permission.) (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
referring physician suspected labral damage or loose bodies, and an arthrogram performed in conjunction with computed tomography (CT) demonstrated loose bodies in the joint (Fig. 30). Referral then was made for arthroscopy to remove the fragments. Referral was delayed, however, because of difficulty obtaining approval from the third-party payor. The evaluation was finally performed 14 months following the initial injury. Examination revealed an antalgic gait. Groin pain was produced just by logrolling the hip back and forth. Range of motion was limited secondary to guarding and pain, even with passive maneuvers. His Harris hip score was 60. Repeat radiographs now showed significant secondary bony changes compared to his initial films (Fig. 3E). Arthroscopy revealed two large loose bodies originating from a
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Figure 3. A, AP radiograph left hip unremarkable. B,Radionuclide scan reveals increased activity, left hip. C,MR image remarkable for pronounced asymmetric effusion, left hip. D, CT coronal reconstruction demonstrates loose bodies. Illustration continued on opposite page
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807
Figure 3 (Continued). f, Follow-up radiograph 13 months post injury reveals secondary changes with superolateral osteophyte formation on the femoral head. F; Loose bodies are evident (asterisk) originating from the acetabulum. Scoring of the femoral head is also evident (arrow) due to third body wear. (From Byrd JWT: Arthroscopy of Select Hip Lesions in Operative Hip Arthroscopy. New York, Thieme; with permission.) (Figures A, B, 0,€, F Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
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crater in the weight bearing portion of the acetabulum, just above the acetabular fossa (Fig. 3F). Significant secondary scoring of the femoral head also was identified due to third body wear. The loose bodies were removed with significant symptomatic improvement. His Harris hip score at 2-year follow-up was 100. Case 3
A 26-year-old male (height 6'3", weight 183 pounds) was referred for evaluation of persistent mechanical left hip pain 13 months following a fall into an empty swimming pool, when he landed on his left side. Examination revealed a normal gait and full passive range of motion of the hip. Logrolling produced mild symptoms. Anterior groin pain was most accentuated with extremes of flexion combined with internal rotation, and abduction combined with external rotation. His Harris hip score was 63. Radiographs were normal. Additionally, a bone scan and MR imaging were performed, and were normal. A fluoroscopically guided intra-articular injection of Bupivacaine temporarily alleviated his symptoms (Fig. 4A). Because of the duration and magnitude of his symptoms, failure of response to conservative measures and temporary relief from an intraarticular injection, arthroscopy of the hip was proposed. Arthroscopy revealed a Grade I11 chondral lesion in the weight bearing portion of the acetabulum, immediately above the acetabular fossa (Fig. 4B). Chondroplasty of this surface was performed with a full radius resector. Subjectively, he did not feel that he experienced much benefit from the arthroscopic procedure. His Harris hip score at 2-year follow-up was 66. Case 4
A 20-year-old division I collegiate wide receiver (height 6'2", weight 175 pounds) was referred for assessment of persistent left hip pain following an injury during spring drills. He described a twisting-lateral impact injury while being tackled. It was painful enough to require crutches for ambulation for 1 week. Since then, he had been unable to resume workouts because his hip pain worseued with activities. Radiographs and MR imaging were normal (Fig. 5A). Examination revealed a normal gait. Groin pain was produced with logrolling the hip, especially internally. Pain was accentuated with extremes of both internal and external rotation with the hip in the 90" flexed position. A painful pop also was elicited when bringing the hip from flexion to extension with neutral rotation. Range of motion was decreased only slightly. His Harris hip score was 65. A fluoroscopically guided intra-articular injection of Bupivacaine provided temporary complete alleviation of his symptoms.
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809
Figure 4. A, AP radiograph of left hip unremarkable. 6, Grade 111 articular fragmentation (arrows) at the medial aspect of superior weightbearing surface of the acetabulum is evident immediately above the acetabular fossa (AF). (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
Because of the magnitude and duration of his symptoms, and because they were unresponsive to conservative measures and temporarily alleviated with an injection, arthroscopy was proposed and performed 7 months following his initial injury. The principal finding was Grade I11 chondromalacia of the weightbearing portion of the acetabulum, immediately above the acetabular fossa (Fig. 5B). Chondroplasty of this area was performed with significant symptomatic improvement. His Harris hip score at 2-year follow-up was 100.
RESULTS (Table 1) This population consists of four males with an average age of 21 years (range 19 to 26 years). The left hip was involved in all cases. A consistent lateral impact mechanism of injury was described,
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Figure 5. A, AP radiograph of left hip unremarkable. B, Grade 111 articular damage, superior medial acetabulum (arrows) immediately above the acetabular fossa (AF). (Courtesy of J. W. Thomas Byrd, MD, Nashville, TN.)
generated by a blow to the greater trochanter from a fall. In each case, the onset of symptoms was immediate and nondisabling, but significant enough to seek medical attention. Initial radiographs were normal in all cases. Bone scan performed in three cases was positive in two. MR imaging, performed in all four cases, revealed signal changes in the femoral head in the one case of femoral articular surface involvement and eventually showed an effusion in the case with acetabular free fragments. It did not accurately define or predict the nature of the intra-articular pathology, however. In the two cases with normal MR imaging findings, symptoms were alleviated temporarily with a fluoroscopically guided intra-articular injection of Bupivacaine. CT scan defined the lesions in the one case of loose bodies. The duration of symptoms prior to arthroscopy averaged 11months (range 7 to 17 months). Arthroscopy defined the extent of intra-articular pathology in each
=
not done
Normal
20
4
N/A
Normal
Normal
15
26
3
7
Normal
Normal
14
19
2
N/A
Normal
+ +
Femoral head signal changes Effusion
Normal
4
20
Bone Scan
MR Imaging
X-rays
1
Duration of Symptoms (months)
Age (years)
Case No.
Table 1
N/A
+ +
N/A
+ N/A
N/A
Injection
N/A
CT
Grade IV chondral injury, femoral head Acetabular osteochondral loose bodies Grade I11 chondromalacia acetabulum Grade I11 chondromalacia acetabulum
Arthroscopic Findings
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case. The pattern of chondral damage was consistent with the mechanism of injury. In one case, a Grade IV chondral lesion occurred on the medial aspect of the femoral head. The three lesions on the acetabular side occurred at the medial aspect of the weightbearing surface, above the acetabular fossa. The magnitude varied with two Grade I11 chondral lesions and one case with osteochondral loose bodies. Three of four patients demonstrated significant improvement with an average preoperative score of 69 compared to 100 at 2-year follow-up. The one poor result (63 preoperative; 66 at 2-year follow-up) occurred in a worker’s compensation case. DISCUSSION
Three nonosseous structures that can be injured and thus produce an elusive cause of mechanical hip pain are the labrum, the articular surface, and the ligamentum teres. Although this paper focuses on articular injuries, a brief synopsis of the other two is worthwhile. Labral injuries were first described when they created a block to reduction of a dislocated hip.7*l5 Subsequently, isolated pathology of the labrum as a source of hip pain was described by Altenberg.’ More recently, the labrum has gained considerable attention through arthroscopy.3,l 3 Labral lesions can occur as a consequence of relatively minor hip trauma, usually a twisting injury. Rupture of the ligamentum teres is likely with a dislocation of the hip. There have been a few case reports of ligament rupture without dislocation.2,8, Villar has classified injuries to the ligamentum teres, including degenerate ligament injuries in association with degenerative disease of the joint.” Chondral injury is a reported and well-accepted indication for hip arthro~copy.~,Little has been written about isolated articular surface injuries in the hip, however. Most chondral damage is associated either with disease or as a remote consequence of previous injury resulting in a post-traumatic degenerative process. This report is the first to focus on acute chondral injuries. The mechanism of injury is often readily discerned from the history. The arthroscopic findings support this lateral impact mechanism. The observation that this injury occurred in physically fit young adult males reflects the following features. The greater trochanter is a relatively subcutaneous structure with little soft tissue absorption of the force generated by the blow. With high bone density, impact on this area is then transferred unchecked to the joint surface. Maximal bone density is achieved in the third decade of life. Perhaps with reduced bone density, either from age or disease, failure would occur through the bone with resultant fracture rather than chondral damage. Conversely, with skeletal immaturity, failure may occur through the physeal plate. The Grade IV chondral injury on the femoral surface represents
LATERAL IMPACT INJURY
813
failure at the tide mark, probably due to shear force. The acetabular lesions have the appearance of chondromalacia, probably due to chondrocyte cell death from excessive compression. In the most extreme example, injury extended into the subchondral plate with accompanying osteocyte demise and resultant osteochondral fragments. The onset of symptoms is immediate, although perhaps not disabling. Persistent dysfunction ensues, which eventually will lead to a more extensive diagnostic work-up. The physical findings are often nonspecific for the nature of intraarticular damage. Intermittent catching, as opposed to just pain, suggests an unstable fragment. Several examination maneuvers have been described, attempting to differentiate various forms of intra-articular injury.14Thus far, we have not found any of these to be reliable. Pain with logrolling the extremity back and forth is the most specific finding for an intra-articular problem, although less sensitive for subtle symptoms. More provocative tests include flexion combined with internal rotation, or abduction combined with external rotation. Both maneuvers can cause mild discomfort normally and need to be compared to the uninvolved hip. Hip symptoms usually are referred to the anterior groin, but can be deep lateral or even posterior. Although the technology is improving, investigative studies may not precisely define a chondral injury. Often indirect or nonspecific findings will suggest that a hip injury has occurred. In the presence of a negative work-up, a fluoroscopically guided intra-articular injection of anesthetic is the most reliable test to localize that the source of the symptoms is intra-articular. In my experience, MR imaging has been unreliable in discerning either bony or cartilaginous loose bodies. CT scans are quite good at showing bony fragments, and arthrography combined with CT techniques usually will show even radiolucent loose bodies. Gadolinium arthrography combined with MR imaging is currently the most promising study. This incorporates many of the best features of these other methods, and the injection may include Bupivacaine to monitor subjective response. Cases 1 and 2 bear special discussion. In Case 1, the long-term prognosis is especially concerning due to the exposed subchondral bone left after excising the chondral fragment. Due to the mechanism of injury, the lesion is on the medial aspect of the femoral head; perhaps this may improve the prognosis, modestly because it does not involve much of the superior surface, which carries most of the weightbearing force. It is suspected that the long-term prognosis will be dictated by the uncertain natural history of the signal changes evident in the femoral head on MR imaging. No further studies have been obtained, as the symptoms have not warranted this. Case 2 highlights the observation of Epstein that retained intraarticular loose bodies in the hip accelerate secondary damage.'O Radiographically, this patient demonstrated secondary changes by the time of arthroscopic intervention. Arthroscopy defined scoring of the femoral
814
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head directly attributable to the loose bodies. The delay in treatment was principally due to initial failure of insurance to approve the procedure. This circumstance should become less of an issue as the fundamental merits of hip arthroscopy are better recognized. SUMMARY
Arthroscopy has helped greatly in understanding the nature of many intra-articular disorders of the hip. It also has provided a better understanding of the pathomechanics and natural progression. This knowledge has aided in improving interpretative clinical skills and investigative techniques. Isolated traumatic chondral injury can occur as a result of impact loading over the greater trochanter. There seems to be a particular propensity for this injury in young physically fit adult males apt to incur this type of blow as a consequence of sport or activity. Initially, this injury may appear innocuous with variable dysfunction. When present, arthroscopy can reliably discern the pathology and often result in significant symptomatic improvement. The long-term consequences of these lesions are still concerning. Although symptomatic improvement from arthroscopic intervention is encouraging, for some cases the long-term influence may only be the knowledge provided for counseling the patient. Nonetheless, arthroscopy can be valuable in both the assessment and management of chondral injuries. References 1. Altenberg AR: Acetabular labrum tears: A cause of hip pain and degenerative arthritis. South Med J 70(2):174-175, 1977 2. Barrett IR, Goldberg JA: Avulsion fracture of the ligamentum teres in a child. A case report. J Bone Joint Surg (Am) 71:438-439, 1989 3. Byrd JWT Labral lesions: An elusive source of hip pain. Case reports and review of the literature. Arthroscopy 12(5):603412, 1996 4. Byrd JWT, Jones K S Prospective analysis of hip arthroscopy. Arthroscopy 16(6):578587, 2000 5. Byrd JWT Hip arthroscopy: The supine position. In McGinty J, Caspari R, Jackson R, et a1 (eds): Operative Arthroscopy, ed 2. New York, Raven Press, 1995, pp 1091-1099 6. Czemy C, Hofmann S, Neuhold A, et al: Lesions of the acetabular labrum: Accuracy of MR imaging and MR arthrography in detection and staging. Radiology 200:225230, 1996 7. Dameron TB: Bucket-handle tear of acetabular labrum accompanying posterior dislocation of the hip. J Bone Joint Surg 41A(1):131-134,1959 8. Delcamp DD, Klaaren HE, Pompe-van Meerfervoot HF: Traumatic avulsion of the ligamentum teres without dislocation of the hip. Two case reports. J Bone Joint Surg 7093S935, 1988 9. Ebrahim NA, Salvolaine ER, Fenton PJ, et al. Calcified ligamentum teres mimicking entrapped intraarticular bony fragments in a patient with acetabular fracture. J Orthop Trauma 5(3):376-378, 1991
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815
10. Epstein HC: Posterior fracture-dislocations of the hip, long term follow up. J Bone Joint Surg 56A(6):1103-1127, 1974 11. Gray AJR, Villar RN: The ligamentum teres of the hip: An arthroscopic classification of its pathology. Arthroscopy 13(5):575-578, 1997 12. Keene GS, Villar RN: Arthroscopic anatomy of the hip: An in vivo study. Arthroscopy 10(4):392-399, 1994 13. Lage LA, Pate1 JV,Villar RN: The acetabular labral tear; an arthroscopic classification. Arthroscopy 12(3):269-272, 1996 14. McCarthy JC, Day B, Busconi B: Hip arthroscopy: Applications and technique. J Am Acad of Orthop Surg 3(3):115-122, 1995 15. Paterson I: The tom acetabular labrum: A block to reduction of a dislocated hip. J Bone Joint Surg 398(2):306-309, 1957 16. Petersilge CA, Haque MA, Petersilge WJ, et al: Acetabular labral tears: Evaluation with MR arthrography. Radiology 200231-235,1996 17. Rashleigh-Belcher HJC, Cannon SR Recurrent dislocation of the hip with a ”BankartType” lesion. J Bone Joint Surg 688(3):398-399, 1986 18. Sampson TG, Glick J M Indications and surgical treatment of hip pathology. In McGinty J, Caspari R, Jackson R, et a1 (eds): Operative Arthroscopy, ed 2. New York, Raven Press, 1995, pp 1067-1078.
Address reprint requests to J. W. Thomas Byrd, MD, Nashville Sports Medicine & Orthopaedic Center 2011 Church Street, Suite 100 Nashville, TN 37203 e-mail [email protected]