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Surgical Approach to the Knee Joint by Section of Collateral Ligament
Surgical Approach to the Knee Joint by Section of Collateral Ligament WILLARD E. DOTTER, M.D.
IN SELECTING a surgical approach to a particular operative field the orthopedist frequently has several possible choices. The object of this presentation is to review the approach to the knee joint by a transverse incision with section of the collateral ligament. The knee is a large joint protected by the collateral ligaments laterally and the cruciate ligaments internally. The major neurovascular supply to the lower leg passes close posteriorly, and the major motor power is transmitted by the patellar tendon anteriorly. The potential area of involvement by the pathologic condition diagnosed preoperatively may be small and well localized as in a cartilage cyst; it may be large and extensively distributed as in osteochondritis dissecans with loose bodies, or it may be vague and undefinable as in an internal derangement. The decision as to the type of incision to be used depends largely on the ability of that approach to fulfill certain requirements. Primarily, the incision should allow performance of the necessary procedure with a minimal amount of trauma to the operative field. Secondly, the pathologic area should be exposed satisfactorily to permit an unobstructed view by the surgeon. Thirdly, the surgical approach should be such as to permit accomplishment of the two preceding requisites without unnecessary duress on the operating team. Also worthy of consideration, however, is the adaptability of the approach should it become necessary to enlarge the operative field by extending the incision. This frequently is preferable to a secondary incision. Finally, the surgical approach should present a degree of trauma to the patient consistent with the preceding requirements yet be associated with minimal postoperative morbidity and disability. The problem, then, is to find a single incision permitting easy visualization and surgical attack of the tibiofemoral articular areas as well as the anterior and posterior compartments of the joint without causing permanent loss of integrity of the knee. The solution is the direct surgical approach through the medial or lateral aspects of the joint by dividing the collateral ligament. 833
834
WILLARD
E.
DOTTER
The direct approach with division of the collateral ligament was initially recommended for meniscectomy.I. 2 Certainly there is no easier or more direct approach to complete removal of the meniscus from the knee joint. The meniscus is so easily viewed that a struggle to place retractors is not necessary. The possibility of a hidden retained tag in the posterior compartment is eliminated. The danger of damage to the popliteal vessels with the blind thrust of the meniscotome is avoided. Gouging the articular surface with scissors or any of the special knives does not occur. The incision with division of the collateral ligament is not limited to meniscectomy, however. It may be used for other conditions requiring extensive exposure of the knee joint, since it does permit direct inspection of the anterior and posterior compartments with minimal trauma from retraction. With proper position of the knee the cruciate ligaments are easily seen, as are the horns, concave rim, and a large portion of the body of the opposite meniscus. With minimal retraction on the patellar tendon the articular surface of the patella can be seen. The suprapatellar pouch can be explored by inserting the gloved finger through the incision into the region. If a direct view is necessary the anterior end of the incision can be extended proximally as far as necessary along the border of the patellar tendon, the patella, and the quadriceps tendon. The patella can be seen and even removed through this extended incision. Another possibility of this versatile incision is to extend the anterior limb distally and the posterior one proximally-a "lazy S"-exposing the entire length of the collateral ligament and permitting repair of cruciate or collateral ligaments. The popliteal fossa can be completely examined under direct vision by flexion of the knee, usually without extending the incision posterior to the hamstring tendons. TOPICAL ANATOMY
With the knee joint slightly flexed the medial and lateral margins of the patellar tendon can be palpated anteriorly. The anterior portions of the tibial condylar articular surfaces are also easily palpated, and the convex anterior femoral condylar surfaces extend proximally paralleling the edges of the patellar tendon. These landmarks indicate the knee joint level anteriorly. By palpating the articular margin of the tibial condyles medially or laterally the joint line can be defined for approximately another inch in either direction. To outline the knee joint level posteriorly from this point becomes difficult because of the dense collateral ligaments crossing over the medial and lateral articular margins of the femur and tibia. These broad, thick ligaments are approximately 1 inch wide at the joint level. At the posterior margins of the ligaments
Surgical Approach to the Knee Joint
835
the tibial and femoral condyles may occasionally be palpated just before they curve sharply toward the center of the knee. Posteriorly, the condyles are covered by the hamstring tendons and soft tissues of the popliteal fossa so that it is impossible to palpate the joint level accurately. SURGICAL ANATOMY
On the medial aspect of the knee (Fig. 1) in the subcutaneous tissues the long saphenous vein crosses the joint level about 1 inch posterior to the collateral ligament and about U to Yz inch anterior to the medial hamstring tendons at the posterior edge of the medial femoral condyle.
Fig. 1. Procedure and structures apparent on medial aspect of knee. C, View of semilunar cartilage and medial femoral condyle; this view of the interior knee can be expanded considerably by abducting the lower leg with the knee flexed 45 degrees or more. The lateral approach presents a similar wide exposure of the interior of the knee from that side.
836
WILLARD
E.
DOTTER
The infrapatellar branch of the saphenous nerve crosses the joint line about midway between the medial collateral ligament and the medial border of the patellar tendon. On either side of the patellar tendon directly beneath the subcutaneous tissue the deep fascia is fused with the fibrous capsule of the joint. This structure is also called the patellar retinaculum. The synovial membrane lies beneath the fibrous capsule, although a portion of the variable-sized infrapatellar fat pad may be interposed. The deep fascia gradually thickens as it extends posteriorly, forming the collateral ligaments. While these structures are described as consisting of a superficial and a deep layer, the two layers often are difficult to define at operation. The medial collateral ligament is broad and flat while the lateral collateral ligament is bandlike. At the posterior margins, the ligaments thin out to be continuous with the fibrous joint capsule as it passes around the condyles into the popliteal fossa. Except for the anterior hom and the first portion of the anterior third of the medial meniscus, the periphery of the anterior and posterior thirds of that cartilage is firmly attached to the deep fascia, while the mid-third is attached to the broad medial collateral ligament. The lateral semilunar cartilage is separated from the fascia and collateral ligament by a thin layer of fibrofatty tissue. The deep fibers of the collateral ligaments are attached close to the articular margins of the femur and tibia on their medial and lateral aspects, the lateral being not as closely attached to the articular margins as the medial. This attachment creates a small synovial-lined space between the articular surface margin, the collateral ligament, and the superior surface of the semilunar cartilage. This is the area where the joint is "tight,". where the surgeon has difficulty placing retractors and where the meniscotomes or other blades may easily damage the articular cartilage. The synovial membrane is firmly attached to the deep surface of the collateralligaments here. Anterior and posterior to this point the membrane is easily stretched or retracted since it is more redundant, as is necessary when it stretches over the condyles on flexion or extension of the knee. OPERATIVE TECHNIQUE
With the patient in a supine position, the knee area is prepared and draped in such a manner as to permit its exposure in a sterile operative field. A tourniquet about the proximal third of the thigh is inflated to hemostatic pressure. The knee and lower leg are elevated on folded sheets to permit approach without interference from the opposite limb. The incision is begun at a point 72 inch lateral to the border of the patellar tendon at the joint level, and is continued posteriorly at the joint level, terminating at the posterior margin of the lateral surface of the femoral condyle. On the medial side the long saphenous vein is
Surgical Approach to the Knee Joint
837
usually seen at the posterior terminal of the wound; it need not be cut and ligated in most cases. The infrapatellar branch of the saphenous nerve should be retracted if encountered. The deep fascia and synovial membrane are incised transversely at the anterior joint line. The joint is opened and the superior surface of the semilunar cartilage is identified. Since the semilunar cartilage rests firmly on the tibia and is more closely attached to it along the convex periphery, the femoral surface of the cartilage is easier to approach, and serves as a guide for extending the incision posteriorly at joint level. The incision is made through the entire thickness of the collateral ligament, fibrous capsule and synovial membrane, terminating at the posterior end of the skin incision. The knee is then flexed approximately 45 degrees; the lower leg is abducted or adducted, as the case may be, to open the joint for inspection and further operation as indicated. To close the wound the knee and lower leg are again placed in a neutral position. The cut edges of the ligament are approximated with two or three horizontal mattress sutures of number 00 chromic catgut. The edges of the synovial membrane and the deep fascia are approximated with simple sutures of number 000 plain catgut and the skin incision is closed with a nonabsorbable suture. A dry dressing is then applied, the tourniquet is released, and a plaster cylinder cast is applied with the knee in a neutral position. POSTOPERATIVE CARE
The patient is allowed to walk as soon as possible, usually two to three days after operation. Crutches or canes are not recommended. The leg remains in a cast for approximately three weeks. If the patient has had difficulty or hesitancy walking and using the quadriceps muscle, the cast is maintained on the leg for an additional period of time so that at least two weeks are spent walking and exercising in a satisfactory manner. When the cast is removed, knee flexion and extension exercises are advised. Again, a cane or crutches are not advised. Follow-up examinations are based on the amount of instruction and care necessary for the patient to return to the preoperative social status. DISCUSSION
Any discussion of this approach must be concerned primarily with the status of the collateral ligaments. There may be considerable argument against section of this structure when the arthrotomy can be done without cutting the ligament. However, after the surgeon has once transected the ligament and discovered the ease of approach and exposure of the joint, he realizes how blind the single anterior approach may be. The secondary posterior incision may be of some value, but the two do not surpass the approach in which the ligament is sectioned.
838
WILLARD
E.
DOTTER
The surgeon may be concerned about the stability of the knee in the postoperative period. This operative approach brings to attention an interesting aspect of the stability of a normal knee. When all the soft tissues including the collateral ligament on the operated side of the knee joint have been sectioned, the lower portion of the leg still maintains its lateral stability as long as the knee is maintained in the neutral position. Providing all ligaments were intact preoperatively, the knee must be flexed about 30 degrees before the lower leg is displaced sufficiently to separate the condylar articular surfaces more than 3i inch. This observation raises the question of the function of the collateral ligament-a subject not within the scope of this presentation. In the plaster cylinder, however, the knee is maintained in a neutral position. When the cast is removed and the knee is in the neutral position, the collateral ligaments still maintain the integrity noted at operation. With good quadriceps muscle power the knee can be successfully stabilized as soon as the cast is removed-even when walking. CONCLUSION
The surgical division of a collateral ligament through a transverse skin incision permits excellent exposure of a major portion of the knee joint. An accurate preoperative diagnosis will dictate whether this exposure is indicated. The function of the collateral ligaments of the knee in extension or flexion warrants additional investigation. REFERENCES
o. E.: Lateral approaches to the knee by releasing the lateral ligaments from the femoral condyles. Soc. Proc., J. Bone & Joint Surgery 35-A: 1027 (Oct.) 1953. 2. Neviaser, J. S.: Division of tibial collateral ligament for removal of medial meniscus. J.A.M.A. 159: 1595-1598 (Dec. 24) 1955. 1. Aufranc,
IN SELECTING a surgical approach to a particular operative field the orthopedist frequently has several possible choices. The object of this presentation is to review the approach to the knee joint by a transverse incision with section of the collateral ligament. The knee is a large joint protected by the collateral ligaments laterally and the cruciate ligaments internally. The major neurovascular supply to the lower leg passes close posteriorly, and the major motor power is transmitted by the patellar tendon anteriorly. The potential area of involvement by the pathologic condition diagnosed preoperatively may be small and well localized as in a cartilage cyst; it may be large and extensively distributed as in osteochondritis dissecans with loose bodies, or it may be vague and undefinable as in an internal derangement. The decision as to the type of incision to be used depends largely on the ability of that approach to fulfill certain requirements. Primarily, the incision should allow performance of the necessary procedure with a minimal amount of trauma to the operative field. Secondly, the pathologic area should be exposed satisfactorily to permit an unobstructed view by the surgeon. Thirdly, the surgical approach should be such as to permit accomplishment of the two preceding requisites without unnecessary duress on the operating team. Also worthy of consideration, however, is the adaptability of the approach should it become necessary to enlarge the operative field by extending the incision. This frequently is preferable to a secondary incision. Finally, the surgical approach should present a degree of trauma to the patient consistent with the preceding requirements yet be associated with minimal postoperative morbidity and disability. The problem, then, is to find a single incision permitting easy visualization and surgical attack of the tibiofemoral articular areas as well as the anterior and posterior compartments of the joint without causing permanent loss of integrity of the knee. The solution is the direct surgical approach through the medial or lateral aspects of the joint by dividing the collateral ligament. 833
834
WILLARD
E.
DOTTER
The direct approach with division of the collateral ligament was initially recommended for meniscectomy.I. 2 Certainly there is no easier or more direct approach to complete removal of the meniscus from the knee joint. The meniscus is so easily viewed that a struggle to place retractors is not necessary. The possibility of a hidden retained tag in the posterior compartment is eliminated. The danger of damage to the popliteal vessels with the blind thrust of the meniscotome is avoided. Gouging the articular surface with scissors or any of the special knives does not occur. The incision with division of the collateral ligament is not limited to meniscectomy, however. It may be used for other conditions requiring extensive exposure of the knee joint, since it does permit direct inspection of the anterior and posterior compartments with minimal trauma from retraction. With proper position of the knee the cruciate ligaments are easily seen, as are the horns, concave rim, and a large portion of the body of the opposite meniscus. With minimal retraction on the patellar tendon the articular surface of the patella can be seen. The suprapatellar pouch can be explored by inserting the gloved finger through the incision into the region. If a direct view is necessary the anterior end of the incision can be extended proximally as far as necessary along the border of the patellar tendon, the patella, and the quadriceps tendon. The patella can be seen and even removed through this extended incision. Another possibility of this versatile incision is to extend the anterior limb distally and the posterior one proximally-a "lazy S"-exposing the entire length of the collateral ligament and permitting repair of cruciate or collateral ligaments. The popliteal fossa can be completely examined under direct vision by flexion of the knee, usually without extending the incision posterior to the hamstring tendons. TOPICAL ANATOMY
With the knee joint slightly flexed the medial and lateral margins of the patellar tendon can be palpated anteriorly. The anterior portions of the tibial condylar articular surfaces are also easily palpated, and the convex anterior femoral condylar surfaces extend proximally paralleling the edges of the patellar tendon. These landmarks indicate the knee joint level anteriorly. By palpating the articular margin of the tibial condyles medially or laterally the joint line can be defined for approximately another inch in either direction. To outline the knee joint level posteriorly from this point becomes difficult because of the dense collateral ligaments crossing over the medial and lateral articular margins of the femur and tibia. These broad, thick ligaments are approximately 1 inch wide at the joint level. At the posterior margins of the ligaments
Surgical Approach to the Knee Joint
835
the tibial and femoral condyles may occasionally be palpated just before they curve sharply toward the center of the knee. Posteriorly, the condyles are covered by the hamstring tendons and soft tissues of the popliteal fossa so that it is impossible to palpate the joint level accurately. SURGICAL ANATOMY
On the medial aspect of the knee (Fig. 1) in the subcutaneous tissues the long saphenous vein crosses the joint level about 1 inch posterior to the collateral ligament and about U to Yz inch anterior to the medial hamstring tendons at the posterior edge of the medial femoral condyle.
Fig. 1. Procedure and structures apparent on medial aspect of knee. C, View of semilunar cartilage and medial femoral condyle; this view of the interior knee can be expanded considerably by abducting the lower leg with the knee flexed 45 degrees or more. The lateral approach presents a similar wide exposure of the interior of the knee from that side.
836
WILLARD
E.
DOTTER
The infrapatellar branch of the saphenous nerve crosses the joint line about midway between the medial collateral ligament and the medial border of the patellar tendon. On either side of the patellar tendon directly beneath the subcutaneous tissue the deep fascia is fused with the fibrous capsule of the joint. This structure is also called the patellar retinaculum. The synovial membrane lies beneath the fibrous capsule, although a portion of the variable-sized infrapatellar fat pad may be interposed. The deep fascia gradually thickens as it extends posteriorly, forming the collateral ligaments. While these structures are described as consisting of a superficial and a deep layer, the two layers often are difficult to define at operation. The medial collateral ligament is broad and flat while the lateral collateral ligament is bandlike. At the posterior margins, the ligaments thin out to be continuous with the fibrous joint capsule as it passes around the condyles into the popliteal fossa. Except for the anterior hom and the first portion of the anterior third of the medial meniscus, the periphery of the anterior and posterior thirds of that cartilage is firmly attached to the deep fascia, while the mid-third is attached to the broad medial collateral ligament. The lateral semilunar cartilage is separated from the fascia and collateral ligament by a thin layer of fibrofatty tissue. The deep fibers of the collateral ligaments are attached close to the articular margins of the femur and tibia on their medial and lateral aspects, the lateral being not as closely attached to the articular margins as the medial. This attachment creates a small synovial-lined space between the articular surface margin, the collateral ligament, and the superior surface of the semilunar cartilage. This is the area where the joint is "tight,". where the surgeon has difficulty placing retractors and where the meniscotomes or other blades may easily damage the articular cartilage. The synovial membrane is firmly attached to the deep surface of the collateralligaments here. Anterior and posterior to this point the membrane is easily stretched or retracted since it is more redundant, as is necessary when it stretches over the condyles on flexion or extension of the knee. OPERATIVE TECHNIQUE
With the patient in a supine position, the knee area is prepared and draped in such a manner as to permit its exposure in a sterile operative field. A tourniquet about the proximal third of the thigh is inflated to hemostatic pressure. The knee and lower leg are elevated on folded sheets to permit approach without interference from the opposite limb. The incision is begun at a point 72 inch lateral to the border of the patellar tendon at the joint level, and is continued posteriorly at the joint level, terminating at the posterior margin of the lateral surface of the femoral condyle. On the medial side the long saphenous vein is
Surgical Approach to the Knee Joint
837
usually seen at the posterior terminal of the wound; it need not be cut and ligated in most cases. The infrapatellar branch of the saphenous nerve should be retracted if encountered. The deep fascia and synovial membrane are incised transversely at the anterior joint line. The joint is opened and the superior surface of the semilunar cartilage is identified. Since the semilunar cartilage rests firmly on the tibia and is more closely attached to it along the convex periphery, the femoral surface of the cartilage is easier to approach, and serves as a guide for extending the incision posteriorly at joint level. The incision is made through the entire thickness of the collateral ligament, fibrous capsule and synovial membrane, terminating at the posterior end of the skin incision. The knee is then flexed approximately 45 degrees; the lower leg is abducted or adducted, as the case may be, to open the joint for inspection and further operation as indicated. To close the wound the knee and lower leg are again placed in a neutral position. The cut edges of the ligament are approximated with two or three horizontal mattress sutures of number 00 chromic catgut. The edges of the synovial membrane and the deep fascia are approximated with simple sutures of number 000 plain catgut and the skin incision is closed with a nonabsorbable suture. A dry dressing is then applied, the tourniquet is released, and a plaster cylinder cast is applied with the knee in a neutral position. POSTOPERATIVE CARE
The patient is allowed to walk as soon as possible, usually two to three days after operation. Crutches or canes are not recommended. The leg remains in a cast for approximately three weeks. If the patient has had difficulty or hesitancy walking and using the quadriceps muscle, the cast is maintained on the leg for an additional period of time so that at least two weeks are spent walking and exercising in a satisfactory manner. When the cast is removed, knee flexion and extension exercises are advised. Again, a cane or crutches are not advised. Follow-up examinations are based on the amount of instruction and care necessary for the patient to return to the preoperative social status. DISCUSSION
Any discussion of this approach must be concerned primarily with the status of the collateral ligaments. There may be considerable argument against section of this structure when the arthrotomy can be done without cutting the ligament. However, after the surgeon has once transected the ligament and discovered the ease of approach and exposure of the joint, he realizes how blind the single anterior approach may be. The secondary posterior incision may be of some value, but the two do not surpass the approach in which the ligament is sectioned.
838
WILLARD
E.
DOTTER
The surgeon may be concerned about the stability of the knee in the postoperative period. This operative approach brings to attention an interesting aspect of the stability of a normal knee. When all the soft tissues including the collateral ligament on the operated side of the knee joint have been sectioned, the lower portion of the leg still maintains its lateral stability as long as the knee is maintained in the neutral position. Providing all ligaments were intact preoperatively, the knee must be flexed about 30 degrees before the lower leg is displaced sufficiently to separate the condylar articular surfaces more than 3i inch. This observation raises the question of the function of the collateral ligament-a subject not within the scope of this presentation. In the plaster cylinder, however, the knee is maintained in a neutral position. When the cast is removed and the knee is in the neutral position, the collateral ligaments still maintain the integrity noted at operation. With good quadriceps muscle power the knee can be successfully stabilized as soon as the cast is removed-even when walking. CONCLUSION
The surgical division of a collateral ligament through a transverse skin incision permits excellent exposure of a major portion of the knee joint. An accurate preoperative diagnosis will dictate whether this exposure is indicated. The function of the collateral ligaments of the knee in extension or flexion warrants additional investigation. REFERENCES
o. E.: Lateral approaches to the knee by releasing the lateral ligaments from the femoral condyles. Soc. Proc., J. Bone & Joint Surgery 35-A: 1027 (Oct.) 1953. 2. Neviaser, J. S.: Division of tibial collateral ligament for removal of medial meniscus. J.A.M.A. 159: 1595-1598 (Dec. 24) 1955. 1. Aufranc,