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What is the terrible triad?
Arthroscopy: The Journal of Arthroscopic and Related Surgery 8(1):19-22 Published by Raven Press, Ltd. 0 1992 Arthroscopy Association of North America
What Is the Terrible Triad? F. Alan Barber, M.D., F.A.C.S.
Summary: In 1936 Campbell asserted that “impairment
of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage.” O’Donoghue in 1950 called attention to “that unhappy triad (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus, and (3) rupture of the anterior cruciate ligament” and recommended early surgical intervention. In 1955 he reported 33 cases with both medial collateral (MCL) and anterior cruciate ligament (ACL) tears, but there were only three lateral meniscus tears reported. Based on a recent report by Shelbourne and Nitz that questions the validity of this unhappy triad, a review of all arthroscopically confirmed acute injuries of second degree or worse to the ACL and MCL was undertaken. Of a total of 52 knees reviewed, 50 knees had third-degree ACL tears and two had second-degree ACL tears. One of the second-degree tears was associated with a second-degree MCL and one with a third-degree MCL tear. Neither had an associated meniscus tear. Forty-five third-degree ACL tears were associated with third-degree MCL tears (group 1) and five with second-degree MCL tears (group 2). Eighty percent (36 knees) of group 1 had lateral meniscus tears. Only 29% of group 1 (13 knees) had associated medial meniscus tears. None of these medial meniscus tears was isolated. Eighty percent (four knees) of group 2 had lateral meniscus tears with only one associated medial meniscus tear. Again, there were no medial meniscus tears in the absence of a lateral meniscus tear. We did not find the combination of injury originally described as the unhappy triad. Key Words: Terrible triad-Anterior cruciate ligament-Medial collateral ligament-Lateral meniscus.
In 1936 Campbell asserted that “impairment of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage” (1). He later stated that “these ligaments are commonly ruptured by the same mechanism which injures the medial cartilage . . .” (2). O’Donoghue in 1950 called attention to “that unhappy triad (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus, and (3) rupture of the anterior cruciate ligament” and recommended early surgical intervention (3). In 1955 he reported 82 major ligament operations, which represented his G-year surgical experience (4). Thirty-three of these 82 (40%)
were for tears of at least the medial collateral (MCL) and anterior cruciate ligaments (ACL). He reported 24 cases with MCL, ACL, and medial meniscus tears; another three cases with the PCL injured as well; three cases with only the MCL and ACL torn; and three cases with MCL, ACL, and both medial and lateral meniscus torn. Of these 33 knee with MCL and ACL tears, there were only three lateral meniscus tears, all associated with medial meniscus tears. Recent reports continue to refer to this combination of injuries as a specific clinical entity (5,6). A recent study by Shelbourne and Nitz has raised the question that the unhappy triad may not occur with the frequency suggested by O’Donoghue (7). To evaluate this premise, a retrospective review of all arthroscopically confirmed acute injuries of seconddegree or worse to the ACL and MCL was undertaken.
From the Division of Orthopedic Surgery, University of Texas Southwestern Medical Center, Dallas, and Plano Orthopedic and Sports Medicine Center, Plano, Texas, U.S.A. Address correspondence and reprint requests to Dr. F. Alan Barber, Plan0 Orthopedic and Sports Medicine Center, 3801 W. 15th Street, Bldg. 2, Suite 250, Plano, TX 75075, U.S.A.
19
20
F. A. BARBER METHODS AND MATERIALS
Fifty-two knees with arthroscopically confirmed acute (<2 months) tears of the MCL and ACL were identified. None of these patients had sustained prior knee injuries or described any knee complaints before the injury. There were 37 men and 15 women. The average age was 30 years (range 1551). There were 32 right knees and 20 left knees injured. The most common sport of injury was skiing (17 knees). Soccer and basketball were both responsible for six injuries, football for five knees, work and motor vehicle accidents for three knees each, and an additional 12 from miscellaneous athletic injuries. The charts, videotapes, and operative notes were reviewed. There were 50 knees with third-degree ACL tears and two with second-degree ACL tears. One second-degree ACL tear was associated with a second-degree MCL tear and one with a thirddegree MCL tear. Neither of these knees had a meniscus tear. The diagnosis of a third-degree ACL tear for this study was made by review of the operative videotape and by a documented preoperative Lachman’s and flexion rotation drawer test performed both in the office and under general anesthesia. Ligament testing demonstrated 33 + laxity (displacement of ~10 mm) in all third-degree ACL tears (6). The two second-degree ACL tears were identified by demonstrating intact fibers inside the opened synovial covering at arthroscopy and by a clinical examination of 2 + (opening of 5-10 mm) under anesthesia. The degree of medial collateral injury was also evaluated by a review of the arthroscopic findings and preoperative office clinical examination and examination under anesthesia. Fresh tearing of the ligament including disruption of the medial capsule and obvious widening of the medial compartment was present in the third-degree disruptions. Fresh bleeding often was observed in the meniscotibial and meniscofemoral ligament area and fibers of the torn MCL could be seen slipping into the medial joint through rents in the synovium. Clinical testing demonstrated 23 + laxity (opening of 3 10 mm) in all third-degree MCL tears and 2 + laxity (opening of 5-10 mm) in the five second-degree MCL tears (6).
five with second-degree MCL tears (group 2). Because none of the second-degree ACL tears had associated meniscal pathology, they were not analyzed further. There was an 80% incidence (36 knees) of lateral meniscus tears in group 1 (Fig. 1). Of these, 13 knees (29% of group 1) had associated medial meniscus tears. Four of the five group 2 knees had lateral meniscus tears, one of which demonstrated an associated medial meniscus tear. There were no medial meniscus tears in the absence of a lateral meniscus tear. Four of the third-degree ACL tears were complete tibia1 spine avulsions. There was no difference in the pattern demonstrated by this subgroup from the others at large. All four were associated with third-degree MCL tears. One had no meniscus tears, two had lateral meniscus tears only, and the fourth had both medial and lateral meniscus tears. Chondral injuries to the medial femoral condyle were noted in three cases, and to the lateral tibia1 plateau in two cases. Two others demonstrated patellar articular cartilage disruptions. The most common tear pattern was a longitudinal full-thickness disruption with some horizontal disruptions of the lateral meniscus extending centrally from the popliteal hiatus in the white/white region of the posterior horn. Sixty percent of all the lateral meniscus tears (25 of 40) were of this “typical tear” type (Fig. 2). Two of these tears had extensions lateral to the popliteus tendon as well. In group 1 the distribution of lateral meniscus tear types was 22 of the typical tear type, seven double bucket handle tears involving both the middle and posterior thirds, three transverse tears, and four miscellaneous types. Group 2 had three typical and one transverse tear (Fig. 3). number of tears
40
30
20
10 0 GROUP
RESULTS Of the 50 third-degree ciated with third-degree Arthroscopy,
Vol. 8, No. 1, 1992
ACL tears, 45 were assoMCL tears (group 1) and
_
500
1
GROUP
2
FIG. 1. Meniscus tears with ACL and MCL injury. Eighty percent of all knees with third-degree ACL tears and either third- or second-degree MCL tears had lateral meniscus tears. In no case was the medial meniscus tom by itself.
THE TERRIBLE
FIG. 2. The typical tear is a longitudinal white/white tear at and central to the popliteal hiatus with horizontal components. This tear type was seen in about 50% of all knees.
Two of the group 1 transverse tears were located in the middle third and one in the posterior horn. The group 2 transverse tear was located in the posterior horn. Medial meniscus tears were always found in conjunction with lateral meniscal tears. In group 1, seven of the 13 tears were longitudinal tears at the synovial meniscal junction. All but one of these were treated by meniscal repair. An additional five tears were bucket handle (white/white) tears in the middle to posterior third of the medial meniscus. There was one horizontal tear as well. The only medial meniscus tear in group 2 was a longitudinal (white/white) posterior horn tear.
21
TRIAD
disruptions of the meniscotibial or meniscofemoral ligaments rather than meniscal substance disruptions in several cases (cases 6, 8, 12, 14, and possibly 14 and 15). No specific discussion of the meniscal pathology is offered in his article; however, a review of the various cases reported provides some data. Of the 22 cases referenced, only 12 were injuries of both MCL and ACL (three of these also had posterior cruciate ligament tears). These 12 ACL/MCL injuries were associated with nine medial meniscus tears (none of these had any reported lateral meniscus damage) and one lateral meniscus tear (without medial meniscus damage). This is the only reference to a lateral meniscus tear, suggesting that in all other cases the lateral meniscus was normal? In the later report (4), there are 33 cases reported with ACLlMCL injuries present. In only three of these was a lateral meniscus tear reported, and in every case the lateral meniscus tear was in conjunction with a medial meniscus tear. Videotape reviews in our series suggest that what may have been previously considered medial meniscus tears was, in fact, capsular tearing. A recent article by Cerabona et al. reported that in combined ACL/collateral ligament injuries the incidence of meniscus tears was 30% medial, 20% lateral, and 3% combined (8). It should be noted that these cases were evaluated by arthrotomy, which probably limited the evaluation of the posterior lateral compartment (as were those of O’Donoghue), in contrast to both our series and the report by Shelboume and Nitz (7). Lateral meniscus tears were found in 80% of third-degree ACL tears when the MCL was also torn. This high frequency suggests that arthroscopic evaluation for meniscus pathology is likely to be
DISCUSSION number of tears
The force necessary to disrupt both the ACL and MCL will often distract the medial compartment and compress the lateral compartment of the knee in conjunction with a rotational stress. This combination of forces directed at the posterior lateral knee would seem the likely cause of the typical lesion. Considering the mechanism of injury, it is not surprising that there were no solitary medial meniscus tears. Instead, these seemed to occur only after the lateral meniscus had already failed. It is difficult to explain why these data differ from the reports by O’Donoghue (3,4), although the drawings that accompany his report (3) illustrate
GROUP
1
GROUP
2
FIG. 3. Lateral meniscus tears with ACL and MCL injury. The typical tear more common than bucket handle or transverse tears of the lateral meniscus.
Arthroscopy,
Vol. 8, No. I, 1992
F.A.BARBER
22
productive and questions the cost effectiveness of other diagnostic procedures such as magnetic resonance imaging for triad injuries. Our experience with magnetic resonance imaging is limited to the most recent six cases. In none of these was there any evidence of subchondral damage present at any location. The most frequent type of lateral meniscus tear found (the typical lesion) in the triad injury was a longitudinal tear with a horizontal component located at and central to the popliteal hiatus. Whereas this injury is not exclusive to the triad, its presence should alert the surgeon to a triad possibility, especially in a patient whose injury was several weeks earlier, providing time for MCL healing. CONCLUSIONS This review of tears of the ACL and MCL suggests that the third component of the triad is actually a lateral meniscus tear. Such a tear can be expected in 80% of combined ACL/MCL ligament injuries. Whereas medial meniscus tears were present in about 25% of this group, they were only found in conjunction with a torn lateral meniscus. A common lateral meniscus tear pattern found in the combined ACL/MCL injury was present in about 50% of all cases. This typical tear was a longitudinal tear with horizontal components at and
Arthroscopy, Vol. 8, No. 1, 1992
central to the popliteal hiatus. The most common medial meniscus tear in this injury is a peripheral synovial meniscal disruption, which is not actually in the substance of the meniscus. These findings question the existence of an acute injury that would cause tears of only the ACL, MCL, and medial meniscus. REFERENCES 1. Campbell WC. Repair of ligaments of the knee, report of a new operation for repair of the anterior crucial ligament. Surg Gynecol Obstet 1936;62:964-8.
2. Campbell WC. Reconstruction of the ligaments of the knee. Am J Surg 1939;43:473-80. 3. O’Donoghue DH. Surgical treatment of fresh injuries to the major ligaments of the knee. J Bone Joint Surg 1950;32A: 721-38. 4. O’Donoghue DH. An analysis of end results of surgical treatment of major injuries to the ligaments of the knee. J Bone Joint Surg 1955;37A:l-13. 5. Ihle CL, Jackson DW. Intra-articular surgical considerations. In: Jackson DW, Drez D Jr, eds. The anterior cruciate deficient knee: new concepts in ligament repair. St. Louis, MO: CV Mosby, 1987:142-67. 6. Sisk DT. Knee injuries. In: Crenshaw AH, ed. Campbells operative orthopaedics. St. Louis, MO: CV Mosby, 1987:2325-6. 7. Shelboume KD, Nitz PA. Knee injury triad: anterior cruciate ligament, medial collateral ligament, and lateral meniscus. Am J Sports Med 1991;19:47&7. 8. Cerabona F, Sherman MF, Bonamo JR, Sklar J. Patterns of meniscal injury with acute anterior cruciate ligament tears. Am .I Sports Med 1988;16:603-9.
What Is the Terrible Triad? F. Alan Barber, M.D., F.A.C.S.
Summary: In 1936 Campbell asserted that “impairment
of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage.” O’Donoghue in 1950 called attention to “that unhappy triad (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus, and (3) rupture of the anterior cruciate ligament” and recommended early surgical intervention. In 1955 he reported 33 cases with both medial collateral (MCL) and anterior cruciate ligament (ACL) tears, but there were only three lateral meniscus tears reported. Based on a recent report by Shelbourne and Nitz that questions the validity of this unhappy triad, a review of all arthroscopically confirmed acute injuries of second degree or worse to the ACL and MCL was undertaken. Of a total of 52 knees reviewed, 50 knees had third-degree ACL tears and two had second-degree ACL tears. One of the second-degree tears was associated with a second-degree MCL and one with a third-degree MCL tear. Neither had an associated meniscus tear. Forty-five third-degree ACL tears were associated with third-degree MCL tears (group 1) and five with second-degree MCL tears (group 2). Eighty percent (36 knees) of group 1 had lateral meniscus tears. Only 29% of group 1 (13 knees) had associated medial meniscus tears. None of these medial meniscus tears was isolated. Eighty percent (four knees) of group 2 had lateral meniscus tears with only one associated medial meniscus tear. Again, there were no medial meniscus tears in the absence of a lateral meniscus tear. We did not find the combination of injury originally described as the unhappy triad. Key Words: Terrible triad-Anterior cruciate ligament-Medial collateral ligament-Lateral meniscus.
In 1936 Campbell asserted that “impairment of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage” (1). He later stated that “these ligaments are commonly ruptured by the same mechanism which injures the medial cartilage . . .” (2). O’Donoghue in 1950 called attention to “that unhappy triad (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus, and (3) rupture of the anterior cruciate ligament” and recommended early surgical intervention (3). In 1955 he reported 82 major ligament operations, which represented his G-year surgical experience (4). Thirty-three of these 82 (40%)
were for tears of at least the medial collateral (MCL) and anterior cruciate ligaments (ACL). He reported 24 cases with MCL, ACL, and medial meniscus tears; another three cases with the PCL injured as well; three cases with only the MCL and ACL torn; and three cases with MCL, ACL, and both medial and lateral meniscus torn. Of these 33 knee with MCL and ACL tears, there were only three lateral meniscus tears, all associated with medial meniscus tears. Recent reports continue to refer to this combination of injuries as a specific clinical entity (5,6). A recent study by Shelbourne and Nitz has raised the question that the unhappy triad may not occur with the frequency suggested by O’Donoghue (7). To evaluate this premise, a retrospective review of all arthroscopically confirmed acute injuries of seconddegree or worse to the ACL and MCL was undertaken.
From the Division of Orthopedic Surgery, University of Texas Southwestern Medical Center, Dallas, and Plano Orthopedic and Sports Medicine Center, Plano, Texas, U.S.A. Address correspondence and reprint requests to Dr. F. Alan Barber, Plan0 Orthopedic and Sports Medicine Center, 3801 W. 15th Street, Bldg. 2, Suite 250, Plano, TX 75075, U.S.A.
19
20
F. A. BARBER METHODS AND MATERIALS
Fifty-two knees with arthroscopically confirmed acute (<2 months) tears of the MCL and ACL were identified. None of these patients had sustained prior knee injuries or described any knee complaints before the injury. There were 37 men and 15 women. The average age was 30 years (range 1551). There were 32 right knees and 20 left knees injured. The most common sport of injury was skiing (17 knees). Soccer and basketball were both responsible for six injuries, football for five knees, work and motor vehicle accidents for three knees each, and an additional 12 from miscellaneous athletic injuries. The charts, videotapes, and operative notes were reviewed. There were 50 knees with third-degree ACL tears and two with second-degree ACL tears. One second-degree ACL tear was associated with a second-degree MCL tear and one with a thirddegree MCL tear. Neither of these knees had a meniscus tear. The diagnosis of a third-degree ACL tear for this study was made by review of the operative videotape and by a documented preoperative Lachman’s and flexion rotation drawer test performed both in the office and under general anesthesia. Ligament testing demonstrated 33 + laxity (displacement of ~10 mm) in all third-degree ACL tears (6). The two second-degree ACL tears were identified by demonstrating intact fibers inside the opened synovial covering at arthroscopy and by a clinical examination of 2 + (opening of 5-10 mm) under anesthesia. The degree of medial collateral injury was also evaluated by a review of the arthroscopic findings and preoperative office clinical examination and examination under anesthesia. Fresh tearing of the ligament including disruption of the medial capsule and obvious widening of the medial compartment was present in the third-degree disruptions. Fresh bleeding often was observed in the meniscotibial and meniscofemoral ligament area and fibers of the torn MCL could be seen slipping into the medial joint through rents in the synovium. Clinical testing demonstrated 23 + laxity (opening of 3 10 mm) in all third-degree MCL tears and 2 + laxity (opening of 5-10 mm) in the five second-degree MCL tears (6).
five with second-degree MCL tears (group 2). Because none of the second-degree ACL tears had associated meniscal pathology, they were not analyzed further. There was an 80% incidence (36 knees) of lateral meniscus tears in group 1 (Fig. 1). Of these, 13 knees (29% of group 1) had associated medial meniscus tears. Four of the five group 2 knees had lateral meniscus tears, one of which demonstrated an associated medial meniscus tear. There were no medial meniscus tears in the absence of a lateral meniscus tear. Four of the third-degree ACL tears were complete tibia1 spine avulsions. There was no difference in the pattern demonstrated by this subgroup from the others at large. All four were associated with third-degree MCL tears. One had no meniscus tears, two had lateral meniscus tears only, and the fourth had both medial and lateral meniscus tears. Chondral injuries to the medial femoral condyle were noted in three cases, and to the lateral tibia1 plateau in two cases. Two others demonstrated patellar articular cartilage disruptions. The most common tear pattern was a longitudinal full-thickness disruption with some horizontal disruptions of the lateral meniscus extending centrally from the popliteal hiatus in the white/white region of the posterior horn. Sixty percent of all the lateral meniscus tears (25 of 40) were of this “typical tear” type (Fig. 2). Two of these tears had extensions lateral to the popliteus tendon as well. In group 1 the distribution of lateral meniscus tear types was 22 of the typical tear type, seven double bucket handle tears involving both the middle and posterior thirds, three transverse tears, and four miscellaneous types. Group 2 had three typical and one transverse tear (Fig. 3). number of tears
40
30
20
10 0 GROUP
RESULTS Of the 50 third-degree ciated with third-degree Arthroscopy,
Vol. 8, No. 1, 1992
ACL tears, 45 were assoMCL tears (group 1) and
_
500
1
GROUP
2
FIG. 1. Meniscus tears with ACL and MCL injury. Eighty percent of all knees with third-degree ACL tears and either third- or second-degree MCL tears had lateral meniscus tears. In no case was the medial meniscus tom by itself.
THE TERRIBLE
FIG. 2. The typical tear is a longitudinal white/white tear at and central to the popliteal hiatus with horizontal components. This tear type was seen in about 50% of all knees.
Two of the group 1 transverse tears were located in the middle third and one in the posterior horn. The group 2 transverse tear was located in the posterior horn. Medial meniscus tears were always found in conjunction with lateral meniscal tears. In group 1, seven of the 13 tears were longitudinal tears at the synovial meniscal junction. All but one of these were treated by meniscal repair. An additional five tears were bucket handle (white/white) tears in the middle to posterior third of the medial meniscus. There was one horizontal tear as well. The only medial meniscus tear in group 2 was a longitudinal (white/white) posterior horn tear.
21
TRIAD
disruptions of the meniscotibial or meniscofemoral ligaments rather than meniscal substance disruptions in several cases (cases 6, 8, 12, 14, and possibly 14 and 15). No specific discussion of the meniscal pathology is offered in his article; however, a review of the various cases reported provides some data. Of the 22 cases referenced, only 12 were injuries of both MCL and ACL (three of these also had posterior cruciate ligament tears). These 12 ACL/MCL injuries were associated with nine medial meniscus tears (none of these had any reported lateral meniscus damage) and one lateral meniscus tear (without medial meniscus damage). This is the only reference to a lateral meniscus tear, suggesting that in all other cases the lateral meniscus was normal? In the later report (4), there are 33 cases reported with ACLlMCL injuries present. In only three of these was a lateral meniscus tear reported, and in every case the lateral meniscus tear was in conjunction with a medial meniscus tear. Videotape reviews in our series suggest that what may have been previously considered medial meniscus tears was, in fact, capsular tearing. A recent article by Cerabona et al. reported that in combined ACL/collateral ligament injuries the incidence of meniscus tears was 30% medial, 20% lateral, and 3% combined (8). It should be noted that these cases were evaluated by arthrotomy, which probably limited the evaluation of the posterior lateral compartment (as were those of O’Donoghue), in contrast to both our series and the report by Shelboume and Nitz (7). Lateral meniscus tears were found in 80% of third-degree ACL tears when the MCL was also torn. This high frequency suggests that arthroscopic evaluation for meniscus pathology is likely to be
DISCUSSION number of tears
The force necessary to disrupt both the ACL and MCL will often distract the medial compartment and compress the lateral compartment of the knee in conjunction with a rotational stress. This combination of forces directed at the posterior lateral knee would seem the likely cause of the typical lesion. Considering the mechanism of injury, it is not surprising that there were no solitary medial meniscus tears. Instead, these seemed to occur only after the lateral meniscus had already failed. It is difficult to explain why these data differ from the reports by O’Donoghue (3,4), although the drawings that accompany his report (3) illustrate
GROUP
1
GROUP
2
FIG. 3. Lateral meniscus tears with ACL and MCL injury. The typical tear more common than bucket handle or transverse tears of the lateral meniscus.
Arthroscopy,
Vol. 8, No. I, 1992
F.A.BARBER
22
productive and questions the cost effectiveness of other diagnostic procedures such as magnetic resonance imaging for triad injuries. Our experience with magnetic resonance imaging is limited to the most recent six cases. In none of these was there any evidence of subchondral damage present at any location. The most frequent type of lateral meniscus tear found (the typical lesion) in the triad injury was a longitudinal tear with a horizontal component located at and central to the popliteal hiatus. Whereas this injury is not exclusive to the triad, its presence should alert the surgeon to a triad possibility, especially in a patient whose injury was several weeks earlier, providing time for MCL healing. CONCLUSIONS This review of tears of the ACL and MCL suggests that the third component of the triad is actually a lateral meniscus tear. Such a tear can be expected in 80% of combined ACL/MCL ligament injuries. Whereas medial meniscus tears were present in about 25% of this group, they were only found in conjunction with a torn lateral meniscus. A common lateral meniscus tear pattern found in the combined ACL/MCL injury was present in about 50% of all cases. This typical tear was a longitudinal tear with horizontal components at and
Arthroscopy, Vol. 8, No. 1, 1992
central to the popliteal hiatus. The most common medial meniscus tear in this injury is a peripheral synovial meniscal disruption, which is not actually in the substance of the meniscus. These findings question the existence of an acute injury that would cause tears of only the ACL, MCL, and medial meniscus. REFERENCES 1. Campbell WC. Repair of ligaments of the knee, report of a new operation for repair of the anterior crucial ligament. Surg Gynecol Obstet 1936;62:964-8.
2. Campbell WC. Reconstruction of the ligaments of the knee. Am J Surg 1939;43:473-80. 3. O’Donoghue DH. Surgical treatment of fresh injuries to the major ligaments of the knee. J Bone Joint Surg 1950;32A: 721-38. 4. O’Donoghue DH. An analysis of end results of surgical treatment of major injuries to the ligaments of the knee. J Bone Joint Surg 1955;37A:l-13. 5. Ihle CL, Jackson DW. Intra-articular surgical considerations. In: Jackson DW, Drez D Jr, eds. The anterior cruciate deficient knee: new concepts in ligament repair. St. Louis, MO: CV Mosby, 1987:142-67. 6. Sisk DT. Knee injuries. In: Crenshaw AH, ed. Campbells operative orthopaedics. St. Louis, MO: CV Mosby, 1987:2325-6. 7. Shelboume KD, Nitz PA. Knee injury triad: anterior cruciate ligament, medial collateral ligament, and lateral meniscus. Am J Sports Med 1991;19:47&7. 8. Cerabona F, Sherman MF, Bonamo JR, Sklar J. Patterns of meniscal injury with acute anterior cruciate ligament tears. Am .I Sports Med 1988;16:603-9.