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medial-side knee injuries
SURGICAL TREATMENT OF ACL/PCL/ MEDIAL-SIDE KNEE INJURIES FREDERICK M. AZAR, MD
The medial cruciate ligament (MCL), anterior cruciate ligament (ACL), and posterior oblique ligament (POL) frequently are injured by a combination of valgus and external rotation forces. Grade I or II MCL injuries alone or in combination with ACL or posterior cruciate ligament (PCL) injuries are treated nonoperatively, with cruciate ligament reconstruction delayed 3 to 6 weeks. Treatment of acute grade III ACL/PCL medial knee injuries remains controversial. Recommendations have included nonoperative treatment of the MCL and reconstruction of the ACL and PCL, acute reconstruction of the MCL and nonoperative treatment of the ACL, and treatment of all grade III injuries with acute repair. For chronic ACL/PCL/medial knee injuries, magnetic resonance imaging and examination under anesthesia are followed by endoscopic ACL/PCL reconstruction. Severe valgus laxity usually requires tightening of the MCL in addition to the posterior capsule, the posterior oblique area of the posteromedial capsule, and the midmedial capsular ligament. Thorough preoperative planning is essential to determine what procedures will be necessary for each patient. KEY WORDS: Cruciate ligaments, posterior oblique ligament, combined injuries, treatment, surgical technique. © 2003 Elsevier Inc. All rights reserved.
Although knee anatomy and biomechanics and evaluation of the injured knee have been described in earlier sections, some points need to be emphasized in the treatment of medial-side knee injuries. This section focuses mainly on the surgical treatment of acute and chronic medial knee instability with anterior and posterior cruciate ligament tears because the treatment of cruciate-ligament injuries without medial instability is described elsewhere in this publication. It is important to be familiar with the 3-layer concept of knee anatomy, as described by Warren and Marshall (Table 1, Figs 1 and 2)1
MEDIAL-SIDED BIOMECHANICS Biomechanically, the MCL is the primary medial stabilizer of the knee in resisting valgus loading.2 The posterior oblique ligament (POL), which blends with the posterior edge of the medial collateral ligament (MCL), helps prevent medial opening during valgus loading with the knee in full extension. When the knee is flexed, the anterior aspect of the POL is actually beneath the MCL. A bursa that separates the 2 structures allows anteroposterior excursion of the MCL during flexion and extension of the knee. This anatomical relationship is important to keep in mind if surgical repair is planned because suturing the
anterior aspect of the POL to the posterior fibers of the MCL with the knee flexed more than 30° can result in a postoperative flexion contracture due to limitation of anteroposterior excursion of the MCL. In addition to providing resistance to valgus stress, the MCL and POL also provide resistance to abnormal external tibial rotation.2-4 Mu¨ller3 labeled this area of the knee the “semimembranosus corner,” and suggested that the semimembranosus musculotendinous unit “dynamizes” this posteromedial corner through its various attachment sites and helps to stabilize the aspect of the knee during active knee flexion. Gardiner et al5 showed in biomechanical studies that strain is significantly different in different regions over the surface of the MCL, and that this distribution of strain changes with flexion angle and with the application of a valgus torque. Strain in the posterior and central portions of the MCL generally decreased with increasing flexion angle, whereas strain in the anterior fibers remained relatively constant with changes in flexion angle. The highest strains in the MCL were found at full extension on the posterior side of the MCL near the femoral insertion. These biomechanical data support the clinical finding that the femoral insertion is the most common location for MCL injuries.
MECHANISM OF INJURY From the University of Tennessee-Campbell Clinic, Department of Orthopedic Surgery, Memphis, TN.. Address reprint requests to Frederick M. Azar, University of Tennessee-Campbell Clinic, Department of Orthopedic Surgery, 910 Madison Avenue, Suite 500, Memphis, TN 38103. © 2003 Elsevier Inc. All rights reserved. 1060-1872/03/1104-0002$30.00/0 doi:10.1016/S1060-1872(03)35916
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Most injuries to the medial side of the knee are caused by a blow to the lateral aspect of the lower thigh or upper leg. The POL and posterior fibers of the MCL usually are damaged by rotational noncontact forces, which can also cause damage to the anterior cruciate ligament (ACL) and possibly to the posterior cruciate ligament (PCL). Because many knee injuries in athletes are caused by a combination
Operative Techniques in Sports Medicine, Vol 11, No 4 (October), 2003: pp 248-256
TABLE 1. Anatomy of Medial Side of the Knee Layer I Layer II Layer III Layers I & II Layers II & III Semitendinosus and gracilis tendons
Sartorius, sartorial fascia Superficial MCL Posterior oblique ligament Semimembranosus Deep MCL Posteromedial capsule Blend anteriorly Blend posteriorly Lie between layers I and II
of valgus and external rotation forces, the MCL, ACL, and POL frequently are damaged in the same knee. Although the classic triad of injuries includes the ACL, the MCL, and the medial meniscus, Shelbourne and Patel6 found this combination rare in athletically active patients, with lateral meniscal injuries more common than medial meniscal injuries in patients with grade II injuries of the MCL and disruption of the ACL. In their study of 163 patients with combined injuries of the ACL and MCL, 58% had lateral meniscal tears and only 20% had medial meniscal tears. They also found that most patients with grade III tears of the MCL and disruption of the ACL had no associated intra-articular injuries. The severity of injuries to the medial side of the knee is graded according to the amount of joint opening when valgus stress is applied to the knee at 0° and 30° of flexion.7 Opening of 0 to 5 mm indicates a grade I (minimal) tear, 6 to 10 mm indicates a grade II (moderate) tear, and more than 10 mm indicates a grade III (complete) tear (Table 2). The amount of laxity in each position of flexion is indicative of the number of medial structures injured.
Valgus laxity at 30° of flexion but not at 0° indicates an isolated MCL injury, whereas valgus laxity at both 30° and 0° indicates injury to the MCL and POL, and likely to the cruciate ligaments. If the knee is stable to valgus stress in full extension, then the POL probably is not significantly injured.
TREATMENT Isolated MCL grade I or grade II or in combination with ACL or PCL injuries are treated nonoperatively,8-10 with pain and swelling control, bracing with a minimally restrictive lateral hinge, and immediate motion and goaldirected functional rehabilitation. Surgery to reconstruct the cruciate ligaments usually is delayed for 3 to 6 weeks (Table 3). Treatment of acute grade III ACL/PCL medial knee injuries remains controversial. Treatment recommendations have included nonoperative treatment of the MCL injury and reconstruction of the ACL and PCL,11-13 acute reconstruction of the MCL and nonoperative treatment of the ACL,14 and treatment of all grade III injuries with acute repair.15,16 Still others prefer to treat grade III injuries of the proximal or mid-substance of the MCL nonoperatively, because more scarring will occur, and treat operatively more distal tears because tears in this area have less healing potential.17,18 Occasionally, a Stener lesion can occur, with the distal attachment of the MCL flipped over the insertion of the pes anserinus and unable to heal. Magnetic resonance imaging is helpful in determining the location of the MCL tear (Fig. 3). Another consideration is the
Fig 1. Cross-section of medial side of the knee demonstrates the 3-layer concept. (From Indelicato PA: Medial and lateral ligament injuries of the knee, in Insall JN, Scott WN (eds): Surgery of the Knee (ed 3). New York, Churchill-Livingstone, 2001.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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Fig 2. With layer 1, midportion of superficial medial ligament, and medial half of semimembranosus sheath removed, structures composing posteromedial corner can be seen. Note distinct insertions of semimembranosus tendon (1 and 2) as opposed to extensions of the semimembranosus tendon sheath (3, 4, and 5). Fibers of extension 5 are variable and appear to have little effect on superficial medial ligament. Semimembranosus sheath and its extensions are in layer 2. Inset shows sites of attachment of superficial medial (SML) and deep medial (DML) ligaments and insertions of the semimembranosus tendon. (C) Oblique popliteal ligament. (Reprinted with permission from Warren LF, Marshall JL: The supporting structures and layers on the medial side of the knee. J Bone Joint Surg Am 61:56-62, 1979.)
chronic ACL/PCL/MCL-deficient knee in which the ACL, PCL, and medial side all need to be reconstructed.
SURGICAL PRINCIPLES Regardless of the operative protocol chosen, some surgical principles should be kept in mind. 1. Thorough preoperative planning is essential to determine what procedures will be necessary and what equipment will be required. Back-up plans should be formulated so that procedure or technique changes can be quickly and easily made if operative findings warrant. Image intensification is recommended. The surgery should be performed at a hospital rather than an outpatient facility, so that appropriate monitoring is possible and a vascular surgeon is available if needed, because the PCL is being reconstructed. Most patients require a short hospital stay after surgery (1 to 3 days).
TABLE 2. Grading of Severity of Ligament Injury Grade
Amount of Opening
Associated Tear
I II III
0-5 mm 5-10 mm ⬎10 mm
Minimal Moderate Complete
2. With acute injuries, careful handling and positioning of the limb during preparation and surgery are necessary to prevent neurovascular injury. A tourniquet is applied, but is not inflated. A limited arthroscopic examination can be performed, but minimal fluid should be used to prevent extravasation into soft tissues and the development of a compartment syndrome. 3. Repair or reconstruction should be performed under direct observation, which requires a relatively extensive exposure. The incision chosen depends on the structures that are to be repaired or reconstructed. A straight medial incision can be used to expose the medial/posteromedial structures; a curved medial utility incision (Fig 4) provides exposure of the ACL,
TABLE 3. Surgical Timing Timing of Surgery
Injury
Immediate (10-14 days)
ACL/PCL/MCL grade III injuries, distal tears
Delayed
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ACL/PCL/MCL grade III injuries with proximal or midsubstance tears ACL/PCL/MCL grade I or II injuries with intact posterior oblique ligament ACL/PCL/MCL grade III injuries with proximal or midsubstance tears
FREDERICK M. AZAR
TABLE 4. Sequence of Surgery ● ● ● ● ● ● ● ● ● ●
Examination under anesthesia Limited arthroscopic examination Repair of meniscal and articular cartilage injuries Placement of tibial tunnel for PCL graft Placement of tibial tunnel for ACL graft Placement of femoral tunnel for ACL graft Placement of femoral tunnel for PCL graft Passage and fixation of PCL graft in femoral tunnel Passage and fixation of ACL graft in femoral tunnel Tensioning and fixation of PCL graft in tibial tunnel with knee flexed 90° ● Tensioning and fixation of ACL graft in tibial tunnel with knee in full extension ● MCL repair, augmentation, or reconstruction
4.
5.
6.
Fig 3. MRI can help identify the location of the MCL tear: femoral (A) or tibial (B) side.
7. PCL, MCL, and posteromedial corner; and a straight midline incision allows exposure of all structures. A posterior L-incision allows exposure of the tibial insertion of the PCL. Whatever approach or approaches are
used, full-thickness skin flaps should be developed with appropriate skin bridges of 7 cm or more to prevent wound-healing problems. Allografts recommended for reconstruction include the Achilles tendon and patellar tendon (bone–patellar tendon–bone graft) for PCL reconstruction, the patellar tendon (bone–patellar tendon–bone graft) for the ACL, and a hamstring/tibialis/Achilles graft for the medial/posteromedial corner. Autografts include bone–patellar tendon–bone, hamstring, or quadriceps grafts. The sequence of surgery is important to ensure technical ease, correct placement of bony tunnels, physiometric placement of graft-fixation sites, and correct tensioning of grafts (Table 4). The posteromedial capsule is more redundant than the posterolateral capsule. Care must be taken, however, to avoid any significant anterior advancement or reefing of the POL because of the risk of postoperative flexion contracture. Tears are repaired with mattress sutures beginning at the most posterior extent (Fig 5A). If repair of the superficial MCL (layer 2) is necessary, then it is important to maintain the broad, flat configuration of the ligament. Bunnell–Kessler sutures can be used for mid-substance tears and sutures anchors, staples, or screws with posts and soft-tissue washers
Fig 4. Curved utility incision for exposure of ACL, PCL, MCL, and posteromedial corner. (Reprinted with permission from Slocum DB, Larson RL, James SL: Late reconstruction of ligamentous injuries of the medial compartment of the knee. Clin Orthop 100:23-33, 1974.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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utility incision (see Fig 4) is used, with care taken during dissection and retraction to avoid injury to the large saphenous vein, which is in the subcutaneous tissue at the posteromedial aspect of the dissection. The infrapatellar branches of the saphenous nerve cannot always be preserved with this incision, although the sartorial branch of the saphenous nerve should be identified and protected because it exits between the sartorius and gracilis. A hematoma in the posteromedial area of the exposure may identify the site of principal damage. The knee should be stressed to evaluate ligamentous and patellar stability. The medial longitudinal extensor retinaculum is incised along the anterior edge of the sartorius from its tibial insertion posteriorly to the posteromedial corner, with care taken not to incise the tibial insertion of the MCL immediately beneath. With the knee flexed, the sartorius and other components of the pes anserinus are retracted to allow inspection of the tibial insertion of the MCL, which is deep and distal to the anterior edge of the sartorius. The assessment of the integrity of this tibial insertion is the first step in surgical identification of the pathological condition. If the MCL is not already exposed by the injury, then an anteromedial parapatellar arthrotomy is made extending from the edge of the vastus medialis muscle distally to join the incision along the anterior edge of the pes anserinus (Fig 6). The medial parapatellar capsular incision is deepened into the joint to allow careful inspection of the joint. If the intra-articular structures have not been evaluated arthroscopically, then the undersurface of the patella, the articular surfaces of the femur and tibia, the medial and lateral menisci, and the ACLs and PCLs should be systematically inspected. With the knee flexed and the heel on the opposite knee, the patellar fat pad can be retracted to
Fig 5. (A) Tears of the posteromedial capsule are reapired with mattress sutures beginning at the most posterior extent. (B) Proximal tears of the superficial MCL can be repaired with a Krachow locking stitch, which allows application of tension to the ligament while maintaining its shape and isometry (Reprinted with permission from Krackow KA, Thomas SC, Jones LC: Ligament-tendon fixation:analysis of a new stitch and comparison with standard techniques. Orthopedics 11: 909-912, 1988.)
for proximal or distal tears. Tissue avulsed from bone should be reattached with suture anchors or by using osseous tunnels (Fig 5B). 8. Restoration of isometry is critical for proximal tears. A Kirschner wire placed through the detached proximal MCL can be placed into various positions on the distal femur to locate the original attachment site.
REPAIR OF ACUTE MEDIAL INSTABILITY: SURGICAL TECHNIQUE After an examination under anesthesia, a limited diagnostic arthroscopy is performed. For the repair, a medial
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Fig 6. An anteromedial parapatellar arthrotomy is used for exposure of the ACL, femoral attachment of the PCL, and anterior portions of the menisci. A posteromedial arthrotomy is made to expose the tibial attachment of the PCL and posteromeidal meniscus. FREDERICK M. AZAR
Fig 7. A common tear pattern of the medial capsule begins near the medial condylar origin and proceeds in a L- or Z-shaped path toward the postero-medial corner. (Reprinted with permission from Miller RH III: Knee injuries, in Canale ST (ed): Campbell’s Operative Orthopaedics (ed 10). St. Louis, Mosby, 2003.)
expose the entire lateral meniscus through the medial parapatellar capsular incision. The cruciate-ligament tears are inspected and palpated with a finger and with ligament hooks. If the menisci are torn within their substance, then irreparable areas are excised, but a meniscal rim or cuff is preserved if possible. The cruciates are reconstructed in the sequence described (see Table 4). A posteromedial arthrotomy is made to expose the tibial attachment of the PCL and posteromedial meniscus (see Fig 6). This approach allows the PCL tibial guide to be placed directly in the appropiate position so that the guide wire and reamer can be palpated and the neurovascular structures protected. If the MCL is avulsed from the tibia beneath the pes, then it is reflected proximally to expose the underlying
midcapsular portion of the medial capsular ligament. A definite interval is present between the MCL and the midscapsular portion of the medial capsular ligament anteriorly so that proximal retraction of the MCL is possible and the anteromedial, midmedial, and posteromedial capsular structures can be readily identified and inspected. Medial capsular tears often begin near the medial condylar origin and proceed in an L- or Z-shaped path toward the posteromedial corner (Fig 7). Tears in the meniscofemoral portion of the deep capsular ligament may leave the peripheral attachment of the medial meniscus undisturbed, and the medial meniscus can be retained. Tears of the weaker meniscotibial portion of the medial capsular ligament frequently accompany tears of the meniscus or its peripheral attachment. All tears in the peripheral meniscal attachment should be repaired as the capsular ligament is repaired (Fig 8), and all tears within the outer 25% to 30% of the substance of the meniscus should be repaired. If the meniscus has been repaired, then these sutures should not be tied until the medial repair is complete. Ligament repair proceeds by first repairing the posteromedial capsule with the knee in no more than 30° of flexion. If the posterior capsule has been torn from its tibial attachment, then it is pulled downward and reattached to the posterior aspect of the tibia (Fig 9). If the posteromedial capsule has been torn in its midportion, then it is approximated with multiple interrupted, nonabsorbable #2 sutures. If the posterior capsule is torn from the femoral attachment, then it is pulled forward and attached with sutures to the adductor tubercle (Fig 10). If the tears have been extensive and the completed repair is fragile, then special procedures can be added to provide reinforcement or dynamic support. For example, suturing the semimembranosus tendon to the posteromedial corner reinforces the POL. Other such procedures include suturing the semimembranosus into the posterior aspect of the MCL, advancing the sartorius and gracilis, pes plasty, and advancing the vastus medialis muscle. Some of these are described in the section on chronic medial instability.
Fig 8. Tears in peripheral meniscal attachment are repaired at the time of capsular ligament repair. (Reprinted with permission from Croft CL, Price CT, Allen WC: Technique of meniscal repair in acute ligamentous injuries of the knee. Gainesville, FL, Department of Orthopaedics, University of Florida Medical Center, 1995.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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Fig 9. If the posterior capsule is torn from its tibial attachment, then it is pulled downward and reattached to the posterior aspect of the tibia. (Reprinted with permission from Hughston JC, Eilers AF: The role of the posterior oblique ligament in repair of acute medial (collateral) ligament tears of the knee. J Bone Joint Surg Am 55:923-940, 1973.)
When all repairs are complete, the wound is closed over a drain. The sartorial fascia is closed with interrupted #0 absorbable sutures before skin closure.
CHRONIC MEDIAL INSTABILITY For chronic ACL/PCL/medial knee injuries, magnetic resonance imaging and examination under anesthesia is followed by endoscopic ACL/PCL reconstruction. Arthro-
Fig 11. Arthroscopic examination will assist in determining the location of injury (meniscofemoral or meniscotibial).
scopic examination will assist in determining the location of injury (meniscofemoral or meniscotibial) (Fig 11). Once the cruciate ligaments are reconstructed endoscopically, the knee is again examined to determine if residual medial laxity is present at 0° or 30° of flexion. Then medial knee reconstruction is performed, usually through a mid-medial approach. The principles of reconstruction of the medial side of the knee are the following: (1) repair and retention of the medial meniscus is possible; (2) reconstruction of the capsular structures, especially the posterior capsule; (3) restoration of the meniscotibial connection of the semimembranous complex; (4) reconstruction of the posterior oblique ligament at the deep posterior corner; (5) re-establishment of the influence of the semimembranous unit to the posterior oblique ligament, medial meniscus, and posterior capsule; and (6) reconstruction of the MCL. Severe valgus laxity usually requires tightening of the MCL in addition to the posterior capsule, the posterior oblique area of the posteromedial capsule, and the midmedial capsular ligament.
RECONSTRUCTION OF CHRONIC INJURY: SURGICAL TECHNIQUE
Fig 10. If the posterior capsule is torn from the femoral attachment, then it is pulled forward and attached to the adductor tubercle. (Reprinted with permission from Hughston JC, Eilers AF: The role of the posterior oblique ligament in repair of acute medial (collateral) ligament tears of the knee. J Bone Joint Surg Am 55:923-940, 1973.)
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After endoscopic reconstruction of the ACL and PCL, a 6to 8-cm midmedial incision is made along the course of the MCL. The sartorial fascia overlying the posteromedial corner of the knee is incised from the level of the vastus medialis anteriorly to the sartorius posteriorly to expose the posterior part of the medial capsule and the semimembranosus tendon. An incision is made along the posterior border of the superficial MCL and the anterior border of the POL. If the superficial MCL is lax, then it can be tightened by detaching it and advancing it superiorly. Next, the POL is imbricated to the posterior border of the MCL in a vest-overpants configuration with No. 2 nonabsorbable mattress sutures (Fig 12). Proper tensioning is critical to prevent flexion contracture. When laxity seems to be principally meniscofemoral rather than meniscotibial, tightening of the medial capsuFREDERICK M. AZAR
Fig 12. POL is imbricated to posterior border of MCL in vest-over-pants configuration. (Reprinted with permission from Hughston JC: The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments in knees with and without an associated rupture of the anterior cruciate ligament. J Bone Joint Surg Am 76:1328-1344, 1994.)
lar ligament by proximal advancement with an intact meniscotibial portion or medial and anterior advancement of the posterior capsule sufficient to correct mild to moderate posterior capsular laxity will not sufficiently disturb an intact medial meniscus to justify its excision. If the meniscotibial (coronary) ligament portion of the capsule is markedly lax and the peripheral attachment of the meniscus is intact, then distal advancement of the posterior and medial capsule may be more difficult. In such instances, rather than excising the meniscus, it is preferable to detach the posterior and posteromedial attachments of the menis-
Fig 14. Tendon is passed over suture post and washer at the medial epicondyle before the proximal end is secured to the posteromedial corner of the tibia.
Fig 13. Lax capsular arm of semimembranosus tendon is pulled anteriorly onto the site of repair of POL and sutured in position. (Reprinted with permission from Hughston JC: The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments in knees with and without an associated rupture of the anterior cruciate ligament. J Bone Joint Surg Am 76:1328-1344, 1994.)
cus along its meniscocapsular attachment, advance the capsule distally, and suture the meniscus to the tightened capsule. If the posterior periphery of the meniscus is already detached, then the capsule is advanced distally and the periphery of the meniscus is sutured. Arthroscopy with valgus stress confirms the location of the injury. If medial laxity is still present, then the direct head of the semimembranosus tendon can be advanced anteriorly. This takes advantage of the fact that the direct head inserts into the posterior tubercle of the tibia and is the strongest soft-tissue anchor point at the posteromedial corner (Fig 13). If laxity is still present or an alternative is required, then a Bosworth reconstruction can be performed. This is accomplished by harvesting the proximal attachment of the semitendinosus, leaving the insertion at the pes intact. The tendon is then passed over a suture post and washer at the medial epicondyle before the proximal aspect of the tendon is secured to the posteromedial corner of the tibia (Fig 14). A Kirschner wire can be placed at the medial epicondyle and the knee can be flexed and extended to confirm the isometric fixation point.
SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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RECONSTRUCTION BY USING ALLOGRAFT TENDONS Autograft tissue can be used for reconstruction of the MCL, but the use of allograft tissue has an advantage over autograft tissue in that autograft sources are limited. Allografts may be preferable to autografts from the medial side of the knee when chronic instability is present because the intact medial structures may provide some stability and sacrifice of the semitendinosus or other medial structure may contribute to medial instability. Frequently used allografts are the semitendinosus and the posterior and anterior tibial tendons. These tendons usually can be doubled on themselves to provide sufficient strength and still have adequate length for reconstruction. The allograft is secured with a biodegradable interference screw in a drill hole at the femoral epicondyle. On the tibial side, it is secured to roughened bone with a screw and spiked softtissue washer or staple at the distal end of the tibial insertion site beneath the pes anserinus tendons in a configuration similar to the Bosworth procedure. Alternatively, sutures can be placed in the free ends of the graft and brought through the tibial drill hole and across the knee to the lateral surface of the tibial to apply tension. The graft is fixed in the tibial tunnel with a biodegradable interference screw. The knee can be moved through a range of motion to determine proper isometric placement of the graft on the femoral side before final fixation. Allograft Achilles tendon also can be used by placing the bony end in a trough proximally and splitting and attaching the tendinous ends distally.
POSTOPERATIVE REHABILITATION The exact postoperative rehabilitation protocol depends on the patient and on the particular injuries treated. Generally, protected weight bearing is enforced for 6 to 8 weeks. The knee is braced in full extension until the patient can demonstrate full, active extension (up to 6 weeks), followed by an unlocked functional brace that is worn until at least 12 weeks after surgery. Patellar mobilization exercises, straight-leg raises, and isometric exercises are begun immediately after surgery. Motion is limited to 0° to 90° for the first 4 weeks, then advanced to full range of motion over the next 4 to 12 weeks. Passive and active-assisted range-of-motion exercises and low-resistance closed-chain exercises are begun at 4 to 8 weeks. Resistance exercises are increased at 8 to 12 weeks, and isokinetic strengthening is begun at 12 to 16 weeks. In
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most patients, full functional recovery can be expected by 6 to 12 months.
REFERENCES 1. Warren LF, Marshall JL: The supporting structures and layers on the medial side of the knee. J Bone Joint Surg Am 61:56-62, 1979 2. Warren LF, Marshall JL, Girgis F: The prime static stabilizer of the medial side of the knee. J Bone Joint Surg Am 56:665-674, 1974 3. Grood ES, Noyes FR, Butler DL, et al: Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg Am 63:1257-1269, 1981 4. Mu¨ ller W: The knee—Form, function, and ligament reconstruction. New York, Springer-Verlag, 1983 5. Gardiner JC, Weiss JA, Rosenberg TD: Strain in the human medial collateral ligament during valgus loading of the knee. Clin Orthop 391:266, 2001 6. Shelbourne KD, Patel DV: Management of combined injuries of the anterior cruciate and medial collateral ligaments. J Bone Joint Surg Am 77:800-806, 1995 7. Hughston JC, Andrews JR, Cross MJ, et al: Classification of knee ligament instabilities. Part I. The medial compartment and cruciate ligament. J Bone Joint Surg Am 58:159-172, 1976 8. Ballmer PM, Jakob RP: The nonoperative treatment of isolated complete tears of the medial collateral ligament of the knee. A prospective study. Arch Orthop Trauma Surg 107:273-276, 1988 9. Indelicator PA: Isolated medial collateral ligament injuries in the knee. J Am Acad Orthop Surg 3:9-14, 1995 10. Indelicato PA, Hermansdorfer J, Huegel M: Nonoperative management of complete tears of the medial collateral ligament of the knee in intercollegiate football players. Clin Orthop 256:174-177, 1990 11. Kannus P: Long-term results of conservative treatment of medial collateral ligament injuries of the knee joint. Clin Orthop 226:103-112, 1988 12. Hillard-Sembell D, Danile DM, Stone ML, et al: Combined injuries of the anterior cruciate and medial collateral ligaments of the knee. Effect of treatment on stability and function of the knee. J Bone Joint Surg Am 78:169-176, 1996 13. Noyes FR, Barber-Westin SD: The treatment of acute combined ruptures of the anterior cruciate and medial ligaments of the knee. Am J Sports Med 23:380-391, 1995 14. Shelbourne KD, Porter DA: Anterior cruciate ligament-medial collateral ligament injury: Nonoperative management of medial collateral ligament tears with anterior cruciate ligament reconstruction. A preliminary report. Am J Sports Med 20:283-286, 1992 15. Larson RL: Combined instabilities of the knee. Clin Orthop 147:L68 – L75, 1980 16. O’Donoghue DH: Reconstruction for medial instability of the knee. Technique and results in sixty cases. J Bone Joint Surg Am 55:941-955, 1973 17. Robins AJ, Newman AP, Burks RT: Postoperative return of motion in anterior cruciate ligament and medial collateral ligament injuries: The effect of medial collateral ligament location. Am J Sports Med 21:20-25, 1993 18. Warren RF, Marshall JL: Injuries of the anterior cruciate and medial collateral ligaments of the knee. A long-term follow-up of 86 cases, Part II. Clin Orthop 136:198-211, 1978
FREDERICK M. AZAR
The medial cruciate ligament (MCL), anterior cruciate ligament (ACL), and posterior oblique ligament (POL) frequently are injured by a combination of valgus and external rotation forces. Grade I or II MCL injuries alone or in combination with ACL or posterior cruciate ligament (PCL) injuries are treated nonoperatively, with cruciate ligament reconstruction delayed 3 to 6 weeks. Treatment of acute grade III ACL/PCL medial knee injuries remains controversial. Recommendations have included nonoperative treatment of the MCL and reconstruction of the ACL and PCL, acute reconstruction of the MCL and nonoperative treatment of the ACL, and treatment of all grade III injuries with acute repair. For chronic ACL/PCL/medial knee injuries, magnetic resonance imaging and examination under anesthesia are followed by endoscopic ACL/PCL reconstruction. Severe valgus laxity usually requires tightening of the MCL in addition to the posterior capsule, the posterior oblique area of the posteromedial capsule, and the midmedial capsular ligament. Thorough preoperative planning is essential to determine what procedures will be necessary for each patient. KEY WORDS: Cruciate ligaments, posterior oblique ligament, combined injuries, treatment, surgical technique. © 2003 Elsevier Inc. All rights reserved.
Although knee anatomy and biomechanics and evaluation of the injured knee have been described in earlier sections, some points need to be emphasized in the treatment of medial-side knee injuries. This section focuses mainly on the surgical treatment of acute and chronic medial knee instability with anterior and posterior cruciate ligament tears because the treatment of cruciate-ligament injuries without medial instability is described elsewhere in this publication. It is important to be familiar with the 3-layer concept of knee anatomy, as described by Warren and Marshall (Table 1, Figs 1 and 2)1
MEDIAL-SIDED BIOMECHANICS Biomechanically, the MCL is the primary medial stabilizer of the knee in resisting valgus loading.2 The posterior oblique ligament (POL), which blends with the posterior edge of the medial collateral ligament (MCL), helps prevent medial opening during valgus loading with the knee in full extension. When the knee is flexed, the anterior aspect of the POL is actually beneath the MCL. A bursa that separates the 2 structures allows anteroposterior excursion of the MCL during flexion and extension of the knee. This anatomical relationship is important to keep in mind if surgical repair is planned because suturing the
anterior aspect of the POL to the posterior fibers of the MCL with the knee flexed more than 30° can result in a postoperative flexion contracture due to limitation of anteroposterior excursion of the MCL. In addition to providing resistance to valgus stress, the MCL and POL also provide resistance to abnormal external tibial rotation.2-4 Mu¨ller3 labeled this area of the knee the “semimembranosus corner,” and suggested that the semimembranosus musculotendinous unit “dynamizes” this posteromedial corner through its various attachment sites and helps to stabilize the aspect of the knee during active knee flexion. Gardiner et al5 showed in biomechanical studies that strain is significantly different in different regions over the surface of the MCL, and that this distribution of strain changes with flexion angle and with the application of a valgus torque. Strain in the posterior and central portions of the MCL generally decreased with increasing flexion angle, whereas strain in the anterior fibers remained relatively constant with changes in flexion angle. The highest strains in the MCL were found at full extension on the posterior side of the MCL near the femoral insertion. These biomechanical data support the clinical finding that the femoral insertion is the most common location for MCL injuries.
MECHANISM OF INJURY From the University of Tennessee-Campbell Clinic, Department of Orthopedic Surgery, Memphis, TN.. Address reprint requests to Frederick M. Azar, University of Tennessee-Campbell Clinic, Department of Orthopedic Surgery, 910 Madison Avenue, Suite 500, Memphis, TN 38103. © 2003 Elsevier Inc. All rights reserved. 1060-1872/03/1104-0002$30.00/0 doi:10.1016/S1060-1872(03)35916
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Most injuries to the medial side of the knee are caused by a blow to the lateral aspect of the lower thigh or upper leg. The POL and posterior fibers of the MCL usually are damaged by rotational noncontact forces, which can also cause damage to the anterior cruciate ligament (ACL) and possibly to the posterior cruciate ligament (PCL). Because many knee injuries in athletes are caused by a combination
Operative Techniques in Sports Medicine, Vol 11, No 4 (October), 2003: pp 248-256
TABLE 1. Anatomy of Medial Side of the Knee Layer I Layer II Layer III Layers I & II Layers II & III Semitendinosus and gracilis tendons
Sartorius, sartorial fascia Superficial MCL Posterior oblique ligament Semimembranosus Deep MCL Posteromedial capsule Blend anteriorly Blend posteriorly Lie between layers I and II
of valgus and external rotation forces, the MCL, ACL, and POL frequently are damaged in the same knee. Although the classic triad of injuries includes the ACL, the MCL, and the medial meniscus, Shelbourne and Patel6 found this combination rare in athletically active patients, with lateral meniscal injuries more common than medial meniscal injuries in patients with grade II injuries of the MCL and disruption of the ACL. In their study of 163 patients with combined injuries of the ACL and MCL, 58% had lateral meniscal tears and only 20% had medial meniscal tears. They also found that most patients with grade III tears of the MCL and disruption of the ACL had no associated intra-articular injuries. The severity of injuries to the medial side of the knee is graded according to the amount of joint opening when valgus stress is applied to the knee at 0° and 30° of flexion.7 Opening of 0 to 5 mm indicates a grade I (minimal) tear, 6 to 10 mm indicates a grade II (moderate) tear, and more than 10 mm indicates a grade III (complete) tear (Table 2). The amount of laxity in each position of flexion is indicative of the number of medial structures injured.
Valgus laxity at 30° of flexion but not at 0° indicates an isolated MCL injury, whereas valgus laxity at both 30° and 0° indicates injury to the MCL and POL, and likely to the cruciate ligaments. If the knee is stable to valgus stress in full extension, then the POL probably is not significantly injured.
TREATMENT Isolated MCL grade I or grade II or in combination with ACL or PCL injuries are treated nonoperatively,8-10 with pain and swelling control, bracing with a minimally restrictive lateral hinge, and immediate motion and goaldirected functional rehabilitation. Surgery to reconstruct the cruciate ligaments usually is delayed for 3 to 6 weeks (Table 3). Treatment of acute grade III ACL/PCL medial knee injuries remains controversial. Treatment recommendations have included nonoperative treatment of the MCL injury and reconstruction of the ACL and PCL,11-13 acute reconstruction of the MCL and nonoperative treatment of the ACL,14 and treatment of all grade III injuries with acute repair.15,16 Still others prefer to treat grade III injuries of the proximal or mid-substance of the MCL nonoperatively, because more scarring will occur, and treat operatively more distal tears because tears in this area have less healing potential.17,18 Occasionally, a Stener lesion can occur, with the distal attachment of the MCL flipped over the insertion of the pes anserinus and unable to heal. Magnetic resonance imaging is helpful in determining the location of the MCL tear (Fig. 3). Another consideration is the
Fig 1. Cross-section of medial side of the knee demonstrates the 3-layer concept. (From Indelicato PA: Medial and lateral ligament injuries of the knee, in Insall JN, Scott WN (eds): Surgery of the Knee (ed 3). New York, Churchill-Livingstone, 2001.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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Fig 2. With layer 1, midportion of superficial medial ligament, and medial half of semimembranosus sheath removed, structures composing posteromedial corner can be seen. Note distinct insertions of semimembranosus tendon (1 and 2) as opposed to extensions of the semimembranosus tendon sheath (3, 4, and 5). Fibers of extension 5 are variable and appear to have little effect on superficial medial ligament. Semimembranosus sheath and its extensions are in layer 2. Inset shows sites of attachment of superficial medial (SML) and deep medial (DML) ligaments and insertions of the semimembranosus tendon. (C) Oblique popliteal ligament. (Reprinted with permission from Warren LF, Marshall JL: The supporting structures and layers on the medial side of the knee. J Bone Joint Surg Am 61:56-62, 1979.)
chronic ACL/PCL/MCL-deficient knee in which the ACL, PCL, and medial side all need to be reconstructed.
SURGICAL PRINCIPLES Regardless of the operative protocol chosen, some surgical principles should be kept in mind. 1. Thorough preoperative planning is essential to determine what procedures will be necessary and what equipment will be required. Back-up plans should be formulated so that procedure or technique changes can be quickly and easily made if operative findings warrant. Image intensification is recommended. The surgery should be performed at a hospital rather than an outpatient facility, so that appropriate monitoring is possible and a vascular surgeon is available if needed, because the PCL is being reconstructed. Most patients require a short hospital stay after surgery (1 to 3 days).
TABLE 2. Grading of Severity of Ligament Injury Grade
Amount of Opening
Associated Tear
I II III
0-5 mm 5-10 mm ⬎10 mm
Minimal Moderate Complete
2. With acute injuries, careful handling and positioning of the limb during preparation and surgery are necessary to prevent neurovascular injury. A tourniquet is applied, but is not inflated. A limited arthroscopic examination can be performed, but minimal fluid should be used to prevent extravasation into soft tissues and the development of a compartment syndrome. 3. Repair or reconstruction should be performed under direct observation, which requires a relatively extensive exposure. The incision chosen depends on the structures that are to be repaired or reconstructed. A straight medial incision can be used to expose the medial/posteromedial structures; a curved medial utility incision (Fig 4) provides exposure of the ACL,
TABLE 3. Surgical Timing Timing of Surgery
Injury
Immediate (10-14 days)
ACL/PCL/MCL grade III injuries, distal tears
Delayed
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ACL/PCL/MCL grade III injuries with proximal or midsubstance tears ACL/PCL/MCL grade I or II injuries with intact posterior oblique ligament ACL/PCL/MCL grade III injuries with proximal or midsubstance tears
FREDERICK M. AZAR
TABLE 4. Sequence of Surgery ● ● ● ● ● ● ● ● ● ●
Examination under anesthesia Limited arthroscopic examination Repair of meniscal and articular cartilage injuries Placement of tibial tunnel for PCL graft Placement of tibial tunnel for ACL graft Placement of femoral tunnel for ACL graft Placement of femoral tunnel for PCL graft Passage and fixation of PCL graft in femoral tunnel Passage and fixation of ACL graft in femoral tunnel Tensioning and fixation of PCL graft in tibial tunnel with knee flexed 90° ● Tensioning and fixation of ACL graft in tibial tunnel with knee in full extension ● MCL repair, augmentation, or reconstruction
4.
5.
6.
Fig 3. MRI can help identify the location of the MCL tear: femoral (A) or tibial (B) side.
7. PCL, MCL, and posteromedial corner; and a straight midline incision allows exposure of all structures. A posterior L-incision allows exposure of the tibial insertion of the PCL. Whatever approach or approaches are
used, full-thickness skin flaps should be developed with appropriate skin bridges of 7 cm or more to prevent wound-healing problems. Allografts recommended for reconstruction include the Achilles tendon and patellar tendon (bone–patellar tendon–bone graft) for PCL reconstruction, the patellar tendon (bone–patellar tendon–bone graft) for the ACL, and a hamstring/tibialis/Achilles graft for the medial/posteromedial corner. Autografts include bone–patellar tendon–bone, hamstring, or quadriceps grafts. The sequence of surgery is important to ensure technical ease, correct placement of bony tunnels, physiometric placement of graft-fixation sites, and correct tensioning of grafts (Table 4). The posteromedial capsule is more redundant than the posterolateral capsule. Care must be taken, however, to avoid any significant anterior advancement or reefing of the POL because of the risk of postoperative flexion contracture. Tears are repaired with mattress sutures beginning at the most posterior extent (Fig 5A). If repair of the superficial MCL (layer 2) is necessary, then it is important to maintain the broad, flat configuration of the ligament. Bunnell–Kessler sutures can be used for mid-substance tears and sutures anchors, staples, or screws with posts and soft-tissue washers
Fig 4. Curved utility incision for exposure of ACL, PCL, MCL, and posteromedial corner. (Reprinted with permission from Slocum DB, Larson RL, James SL: Late reconstruction of ligamentous injuries of the medial compartment of the knee. Clin Orthop 100:23-33, 1974.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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utility incision (see Fig 4) is used, with care taken during dissection and retraction to avoid injury to the large saphenous vein, which is in the subcutaneous tissue at the posteromedial aspect of the dissection. The infrapatellar branches of the saphenous nerve cannot always be preserved with this incision, although the sartorial branch of the saphenous nerve should be identified and protected because it exits between the sartorius and gracilis. A hematoma in the posteromedial area of the exposure may identify the site of principal damage. The knee should be stressed to evaluate ligamentous and patellar stability. The medial longitudinal extensor retinaculum is incised along the anterior edge of the sartorius from its tibial insertion posteriorly to the posteromedial corner, with care taken not to incise the tibial insertion of the MCL immediately beneath. With the knee flexed, the sartorius and other components of the pes anserinus are retracted to allow inspection of the tibial insertion of the MCL, which is deep and distal to the anterior edge of the sartorius. The assessment of the integrity of this tibial insertion is the first step in surgical identification of the pathological condition. If the MCL is not already exposed by the injury, then an anteromedial parapatellar arthrotomy is made extending from the edge of the vastus medialis muscle distally to join the incision along the anterior edge of the pes anserinus (Fig 6). The medial parapatellar capsular incision is deepened into the joint to allow careful inspection of the joint. If the intra-articular structures have not been evaluated arthroscopically, then the undersurface of the patella, the articular surfaces of the femur and tibia, the medial and lateral menisci, and the ACLs and PCLs should be systematically inspected. With the knee flexed and the heel on the opposite knee, the patellar fat pad can be retracted to
Fig 5. (A) Tears of the posteromedial capsule are reapired with mattress sutures beginning at the most posterior extent. (B) Proximal tears of the superficial MCL can be repaired with a Krachow locking stitch, which allows application of tension to the ligament while maintaining its shape and isometry (Reprinted with permission from Krackow KA, Thomas SC, Jones LC: Ligament-tendon fixation:analysis of a new stitch and comparison with standard techniques. Orthopedics 11: 909-912, 1988.)
for proximal or distal tears. Tissue avulsed from bone should be reattached with suture anchors or by using osseous tunnels (Fig 5B). 8. Restoration of isometry is critical for proximal tears. A Kirschner wire placed through the detached proximal MCL can be placed into various positions on the distal femur to locate the original attachment site.
REPAIR OF ACUTE MEDIAL INSTABILITY: SURGICAL TECHNIQUE After an examination under anesthesia, a limited diagnostic arthroscopy is performed. For the repair, a medial
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Fig 6. An anteromedial parapatellar arthrotomy is used for exposure of the ACL, femoral attachment of the PCL, and anterior portions of the menisci. A posteromedial arthrotomy is made to expose the tibial attachment of the PCL and posteromeidal meniscus. FREDERICK M. AZAR
Fig 7. A common tear pattern of the medial capsule begins near the medial condylar origin and proceeds in a L- or Z-shaped path toward the postero-medial corner. (Reprinted with permission from Miller RH III: Knee injuries, in Canale ST (ed): Campbell’s Operative Orthopaedics (ed 10). St. Louis, Mosby, 2003.)
expose the entire lateral meniscus through the medial parapatellar capsular incision. The cruciate-ligament tears are inspected and palpated with a finger and with ligament hooks. If the menisci are torn within their substance, then irreparable areas are excised, but a meniscal rim or cuff is preserved if possible. The cruciates are reconstructed in the sequence described (see Table 4). A posteromedial arthrotomy is made to expose the tibial attachment of the PCL and posteromedial meniscus (see Fig 6). This approach allows the PCL tibial guide to be placed directly in the appropiate position so that the guide wire and reamer can be palpated and the neurovascular structures protected. If the MCL is avulsed from the tibia beneath the pes, then it is reflected proximally to expose the underlying
midcapsular portion of the medial capsular ligament. A definite interval is present between the MCL and the midscapsular portion of the medial capsular ligament anteriorly so that proximal retraction of the MCL is possible and the anteromedial, midmedial, and posteromedial capsular structures can be readily identified and inspected. Medial capsular tears often begin near the medial condylar origin and proceed in an L- or Z-shaped path toward the posteromedial corner (Fig 7). Tears in the meniscofemoral portion of the deep capsular ligament may leave the peripheral attachment of the medial meniscus undisturbed, and the medial meniscus can be retained. Tears of the weaker meniscotibial portion of the medial capsular ligament frequently accompany tears of the meniscus or its peripheral attachment. All tears in the peripheral meniscal attachment should be repaired as the capsular ligament is repaired (Fig 8), and all tears within the outer 25% to 30% of the substance of the meniscus should be repaired. If the meniscus has been repaired, then these sutures should not be tied until the medial repair is complete. Ligament repair proceeds by first repairing the posteromedial capsule with the knee in no more than 30° of flexion. If the posterior capsule has been torn from its tibial attachment, then it is pulled downward and reattached to the posterior aspect of the tibia (Fig 9). If the posteromedial capsule has been torn in its midportion, then it is approximated with multiple interrupted, nonabsorbable #2 sutures. If the posterior capsule is torn from the femoral attachment, then it is pulled forward and attached with sutures to the adductor tubercle (Fig 10). If the tears have been extensive and the completed repair is fragile, then special procedures can be added to provide reinforcement or dynamic support. For example, suturing the semimembranosus tendon to the posteromedial corner reinforces the POL. Other such procedures include suturing the semimembranosus into the posterior aspect of the MCL, advancing the sartorius and gracilis, pes plasty, and advancing the vastus medialis muscle. Some of these are described in the section on chronic medial instability.
Fig 8. Tears in peripheral meniscal attachment are repaired at the time of capsular ligament repair. (Reprinted with permission from Croft CL, Price CT, Allen WC: Technique of meniscal repair in acute ligamentous injuries of the knee. Gainesville, FL, Department of Orthopaedics, University of Florida Medical Center, 1995.) SURGICAL TREATMENT OF ACL/PCL MEDIAL SIDE KNEE INJURIES
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Fig 9. If the posterior capsule is torn from its tibial attachment, then it is pulled downward and reattached to the posterior aspect of the tibia. (Reprinted with permission from Hughston JC, Eilers AF: The role of the posterior oblique ligament in repair of acute medial (collateral) ligament tears of the knee. J Bone Joint Surg Am 55:923-940, 1973.)
When all repairs are complete, the wound is closed over a drain. The sartorial fascia is closed with interrupted #0 absorbable sutures before skin closure.
CHRONIC MEDIAL INSTABILITY For chronic ACL/PCL/medial knee injuries, magnetic resonance imaging and examination under anesthesia is followed by endoscopic ACL/PCL reconstruction. Arthro-
Fig 11. Arthroscopic examination will assist in determining the location of injury (meniscofemoral or meniscotibial).
scopic examination will assist in determining the location of injury (meniscofemoral or meniscotibial) (Fig 11). Once the cruciate ligaments are reconstructed endoscopically, the knee is again examined to determine if residual medial laxity is present at 0° or 30° of flexion. Then medial knee reconstruction is performed, usually through a mid-medial approach. The principles of reconstruction of the medial side of the knee are the following: (1) repair and retention of the medial meniscus is possible; (2) reconstruction of the capsular structures, especially the posterior capsule; (3) restoration of the meniscotibial connection of the semimembranous complex; (4) reconstruction of the posterior oblique ligament at the deep posterior corner; (5) re-establishment of the influence of the semimembranous unit to the posterior oblique ligament, medial meniscus, and posterior capsule; and (6) reconstruction of the MCL. Severe valgus laxity usually requires tightening of the MCL in addition to the posterior capsule, the posterior oblique area of the posteromedial capsule, and the midmedial capsular ligament.
RECONSTRUCTION OF CHRONIC INJURY: SURGICAL TECHNIQUE
Fig 10. If the posterior capsule is torn from the femoral attachment, then it is pulled forward and attached to the adductor tubercle. (Reprinted with permission from Hughston JC, Eilers AF: The role of the posterior oblique ligament in repair of acute medial (collateral) ligament tears of the knee. J Bone Joint Surg Am 55:923-940, 1973.)
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After endoscopic reconstruction of the ACL and PCL, a 6to 8-cm midmedial incision is made along the course of the MCL. The sartorial fascia overlying the posteromedial corner of the knee is incised from the level of the vastus medialis anteriorly to the sartorius posteriorly to expose the posterior part of the medial capsule and the semimembranosus tendon. An incision is made along the posterior border of the superficial MCL and the anterior border of the POL. If the superficial MCL is lax, then it can be tightened by detaching it and advancing it superiorly. Next, the POL is imbricated to the posterior border of the MCL in a vest-overpants configuration with No. 2 nonabsorbable mattress sutures (Fig 12). Proper tensioning is critical to prevent flexion contracture. When laxity seems to be principally meniscofemoral rather than meniscotibial, tightening of the medial capsuFREDERICK M. AZAR
Fig 12. POL is imbricated to posterior border of MCL in vest-over-pants configuration. (Reprinted with permission from Hughston JC: The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments in knees with and without an associated rupture of the anterior cruciate ligament. J Bone Joint Surg Am 76:1328-1344, 1994.)
lar ligament by proximal advancement with an intact meniscotibial portion or medial and anterior advancement of the posterior capsule sufficient to correct mild to moderate posterior capsular laxity will not sufficiently disturb an intact medial meniscus to justify its excision. If the meniscotibial (coronary) ligament portion of the capsule is markedly lax and the peripheral attachment of the meniscus is intact, then distal advancement of the posterior and medial capsule may be more difficult. In such instances, rather than excising the meniscus, it is preferable to detach the posterior and posteromedial attachments of the menis-
Fig 14. Tendon is passed over suture post and washer at the medial epicondyle before the proximal end is secured to the posteromedial corner of the tibia.
Fig 13. Lax capsular arm of semimembranosus tendon is pulled anteriorly onto the site of repair of POL and sutured in position. (Reprinted with permission from Hughston JC: The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments in knees with and without an associated rupture of the anterior cruciate ligament. J Bone Joint Surg Am 76:1328-1344, 1994.)
cus along its meniscocapsular attachment, advance the capsule distally, and suture the meniscus to the tightened capsule. If the posterior periphery of the meniscus is already detached, then the capsule is advanced distally and the periphery of the meniscus is sutured. Arthroscopy with valgus stress confirms the location of the injury. If medial laxity is still present, then the direct head of the semimembranosus tendon can be advanced anteriorly. This takes advantage of the fact that the direct head inserts into the posterior tubercle of the tibia and is the strongest soft-tissue anchor point at the posteromedial corner (Fig 13). If laxity is still present or an alternative is required, then a Bosworth reconstruction can be performed. This is accomplished by harvesting the proximal attachment of the semitendinosus, leaving the insertion at the pes intact. The tendon is then passed over a suture post and washer at the medial epicondyle before the proximal aspect of the tendon is secured to the posteromedial corner of the tibia (Fig 14). A Kirschner wire can be placed at the medial epicondyle and the knee can be flexed and extended to confirm the isometric fixation point.
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RECONSTRUCTION BY USING ALLOGRAFT TENDONS Autograft tissue can be used for reconstruction of the MCL, but the use of allograft tissue has an advantage over autograft tissue in that autograft sources are limited. Allografts may be preferable to autografts from the medial side of the knee when chronic instability is present because the intact medial structures may provide some stability and sacrifice of the semitendinosus or other medial structure may contribute to medial instability. Frequently used allografts are the semitendinosus and the posterior and anterior tibial tendons. These tendons usually can be doubled on themselves to provide sufficient strength and still have adequate length for reconstruction. The allograft is secured with a biodegradable interference screw in a drill hole at the femoral epicondyle. On the tibial side, it is secured to roughened bone with a screw and spiked softtissue washer or staple at the distal end of the tibial insertion site beneath the pes anserinus tendons in a configuration similar to the Bosworth procedure. Alternatively, sutures can be placed in the free ends of the graft and brought through the tibial drill hole and across the knee to the lateral surface of the tibial to apply tension. The graft is fixed in the tibial tunnel with a biodegradable interference screw. The knee can be moved through a range of motion to determine proper isometric placement of the graft on the femoral side before final fixation. Allograft Achilles tendon also can be used by placing the bony end in a trough proximally and splitting and attaching the tendinous ends distally.
POSTOPERATIVE REHABILITATION The exact postoperative rehabilitation protocol depends on the patient and on the particular injuries treated. Generally, protected weight bearing is enforced for 6 to 8 weeks. The knee is braced in full extension until the patient can demonstrate full, active extension (up to 6 weeks), followed by an unlocked functional brace that is worn until at least 12 weeks after surgery. Patellar mobilization exercises, straight-leg raises, and isometric exercises are begun immediately after surgery. Motion is limited to 0° to 90° for the first 4 weeks, then advanced to full range of motion over the next 4 to 12 weeks. Passive and active-assisted range-of-motion exercises and low-resistance closed-chain exercises are begun at 4 to 8 weeks. Resistance exercises are increased at 8 to 12 weeks, and isokinetic strengthening is begun at 12 to 16 weeks. In
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most patients, full functional recovery can be expected by 6 to 12 months.
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FREDERICK M. AZAR