KNEE SURGERY APPROACH TECHNIQUES
- Medial Parapatellar Approach
The medial parapatellar (MPP) approach, which was described by von Langenbeck in 1878 (1), has intra-articular and periarticular structures that can be used for synovectomy, medial meniscus excision, total knee arthroplasty (TKA), free body removal, ligament reconstructions, septic arthritis surgery and trauma surgery. It is a transportation approach. The standard approach used in TDA applications is the MPP approach. While the patient is in the supine position on the operating table, the knee joint is fixed in a 90-degree flexion position using an under-heel pillow. A support with a table attachment is placed on the upper outer part of the thigh to prevent the leg from slipping into abduction. A skin incision is made from the midline of the knee, approximately 5 cm proximal to the upper pole of the patella, to approximately 0.5 cm medial to the tuberositas tibia. After controlling the bleeding, the vastus medialis muscle is separated proximally with a quadriceps tendon incision, and the incision is advanced from the medial of the patella to the distal medial of the patellar tendon and terminated approximately 0.5-1 cm medial to the tuberositas tibia. To be used during closure, 0.5 cm capsule should be left in the patellar part while the incision passes medial to the patella. In case of difficulty in retraction of the patella, the proximal incision can be extended. In order to facilitate retraction, the patellar tendon tuberositas can be carefully scraped subpreiostally from its attachment to the tibia immediately medial. Especially in cases of arthroplasty, fat pad excision can be performed behind the patella in order to increase joint visual dominance (2) (3) (4).
During the MPP surgical approach, the infrapatellar branch of the saphenous nerve may be damaged. Painful neuroma may occur after the operation due to the cutting of the nerve. Since the numbness area to be formed will not cause a problem, its repair is not recommended. However, in order to reduce the risk of neuroma formation, the proximal end of the cut nerve should be embedded in the adipose tissue (4). The MPP approach may cause patellofemoral complications such as patellar instability, lateral dislocation or subluxation of the patella, and avascular necrosis at a rate of 1.5% to 12% after the operation (6). It may require additional surgical approaches such as lateral retinacular release. Especially during TKA surgery, care should be taken not to leave the patellar tendon tuberositas tibia attachment site during flexion movement along with lateral retraction of the patella. The disadvantage of the MPP approach is the loss of strength in the extension after the operation due to the quadriceps tendon incision and the difficulty of rehabilitation due to this (2) (3) (4).
- Midvastus Approach
The Midvastus (MV) surgical approach, defined by Engh (7) in 1997, is a minimally invasive form of arthrotomy that can be used in TKA and single-compartment knee arthroplasty. The patient is in the supine position, the knee joint is flexed to 90 degrees and the patient is positioned by placing the thigh support so that the leg does not go into abduction. Following the midline skin incision and bleeding control, the junction of the patella mediali and vastus medialis muscle with the quadriceps tendon is exposed. The vastus medialis muscle is separated from the supreomedial of the patella in a full thickness parallel to the muscle fibers. Then, the incision is extended from the patella superomedial to approximately 0.5-1 cm medial to the tuberositas tibia, leaving a 0.5 cm capsule on the patellar side, and the joint is opened. The distal attachment of the patellar tendon is carefully scraped subperiosteally. Capsular connections in the suprapatellar pouch are cut to enable patella retraction. The fat pad part behind the patella is excised, and a view of the entire joint is obtained (2) (3) (4)(8).
The MV approach may provide advantages such as less post-operative pain and faster knee extension return compared to the MPP technique, since the extensor mechanism cannot be damaged due to the absence of quadriceps tendon incision. In addition, it is argued that fewer patellofemoral complications and the need for lateral retinacular release are required. The MV approach is not recommended especially in knees with valgus deformity and in obese patients due to the difficulty of application. (2)(8)
- Subvastus Approach
Due to the quadriceps strength loss and patellofemoral complications due to the standard MPP approach, different arthrotomy approaches have been sought. The subvastus surgical (SV) approach was defined by Erkes (9) in 1929; Compared to the MPP intervention, it is a more protective and anatomical approach, as well as one of the minimally invasive approaches. As in other approaches, the vastus medialis muscle is dissected from the medial posterior intramuscular septum to the insertion point of the patella superior muscle, following a midline skin incision and bleeding control while the patient is in the supine position and the knee joint is in 90 degrees flexion. During this dissection, if the dissection extends too far proximally, the intermuscular or articular branch of the descending genicular artery may be damaged. Then, the incision is advanced medial to the patellar tendon and extended to approximately 0.5-1 cm medial to the tuberositas tibia (2) (3) (4).
Since the integrity of the quadriceps tendon is not disrupted in the LV approach, there is no decrease in the strength of the extensor mechanism (10). Since the medial vessels that feed the patella are not damaged, the risk of patella circulation problem is also very low. In addition, since the vastus medialis muscle integrity is not impaired, its innervation is not impaired. In addition to these advantages, Hunter duct and neurovascular structures are at risk during intermuscular septum dissection. LV intervention in knees with severe deformity and in obese patients is not an appropriate approach because of the risk of damage to neurovascular structures. Another disadvantage of the LV approach is the risk of hematoma and necrosis in the subvastus muscle after the operation (2) (3) (4).
- Lateral Parapatellar Approach
The lateral parapatellar (LPP) approach, which was first published in 1982 (11), is an approach used for TKA or single-compartment knee arthroplasty surgery, especially in knees with fixed valgus deformities and knees with lateral subluxation of the patella. Like other approaches, the LPP approach is performed with the patient in the supine position with the knee joint in 90-degree flexion. The skin incision is advanced 5 cm proximal to the patella along the VL muscle from the lateral border of the patella to the gerdys tubercle distally. Following bleeding control, the iliotibial ligament is dissected proximally from the vastus lateralis muscle. During this dissection, attention should be paid to the peroneal nerve. The incision, which starts from the lateral quadriceps tendon proximally, passes through the lateral patella and extends to the midpoint of the Gerdys tubercle. In the distal retinacular incision, the Gerdys tubercle is scraped from proximal to distal and from lateral to medial subperiosteally. (2) (3).
It is preferred in knees with fixed valgus deformities, since it is easier to reach the posterolateral joint space in the LPP approach. Since the integrity of the medial retinaculum is not impaired, patellofemoral compliance is easier to achieve. The most important disadvantage of the LPP procedure is the risk of developing drop foot due to injury to the peroneal nerve. Care should be taken to preserve the integrity of the lateral collateral ligament. Since it will be difficult to reach the medial knee in the LPP approach, it is not recommended for knees with fixed varus deformities. (2) (4)
- Extended Approaches
Extended approaches are used in cases where more joint field of view is desired, where standard arthrotomy is insufficient. These extended approaches; Quadriceps Turndown (VY Plasti), Tibial Tubercle Osteotomy and Rectus Snip interventions. Extended approaches can be used in deformities with severe limitation of motion, ankylosed knees and revision surgeries where the patella cannot be tilted laterally. (2)(8)
The quadriceps VY plasty technique described by Coonse and Adams involved inverting the quadriceps muscle tendon in an inverted V shape to provide a wide arthrotomy. Later, this technique was developed and used as an extended MPP approach. This technique, which involves a large incision, cannot be recommended by Insall. The rectus snip technique was described by Insall and involves advancing the MPP approach proximally towards the vastus lateralis. In this technique, the lateral superior genicular artery must be located proximally and protected. In the Rectus Snip technique, the quadriceps tendon is easily tilted laterally together with the patella and patellar tendon, providing a wide field of view. Whiteside and Ohl suggested a tuberositas tibial osteotomy to overturn the patella laterally. In this technique, the tuberositas tibia is osteotomized and lifted to contain at least 6 cm of bone block, thus providing a wide viewing angle. After the operation, the tuberositas tibia should be fixed with screws or cerclage. (2)(8)
When access to neurovascular structures in the posterior of the knee joint is required, posterior cruciate ligament fractures, contractures in the gastrocnemius and hamstring muscles, and excision of popliteal cysts are applied to the knee joint. The patient is placed in the prone position on the operating table. The skin incision starts from the lateral biceps femorais muscle proximally, proceeds obliquely from the popliteal region, and is advanced straight distally over the medial head of the gastrocnemius. With superficial dissection, flaps containing skin and subcutaneous adipose tissue are excluded. After finding the small saphenous vein and the medial sural cutaneous nerve just lateral to it, the popoliteal fascia is opened with an incision made just lateral to the vein. By following the medial sural cutaneous nerve, the tibial nerve and proximal peroneal nerve are exposed. The common peroneal nerve branches off from the tibial nerve at the apex of the popliteal pit between the biceps femoris laterally and the semimembranosus muscle medially. Later on, the popliteal artery and vein are found deep down. If there is a situation where the artery needs to be mobilized, its branches should be tied. The popliteal vein lies just medial to the artery. Care must be taken during mobilization. An intimal injury may cause post-operative thrombosis. The two heads of the gastrocnemius muscle leave the capsule. Then, the muscle structures forming the popliteal pit are removed to the edge without damaging the neurovascular structures, and the joint capsule is exposed. (3) (12) (13)
In the posterior approach, a painful neuroma may occur if the medial sural cutaneous nerve extending lateral to the lesser saphenous vein is cut. The tibial and common peroneal nerves may be damaged in the popliteal pit. Care should be taken not to ligate the popliteal veins during the ligation of the lesser saphenous vein. (3)
Medial surgical approach; It is an approach that provides access and intervention to the medial connective tissues of the knee joint. It is preferred for medial meniscus repair or excision, superficial medial collateral ligament and capsule repair. While the patient is in the supine position on the operating table, the foot on the side to be operated is brought over the opposite leg, and the knee joint is brought to 60 degrees of flexion and the leg to abduction and external rotation. A skin incision is made distal to the femur, extending from approximately 2 cm proximal to the adductor tubercle to 6 cm distal to the joint, inclined towards the anterior of the tibia. During dissection, the infrapatellar branch of the saphenous nerve is often sacrificed because it passes transversely from the surgical site. However, the saphenous nerve, which runs between the gracilis and sartorius muscles, should be preserved. An incision is made in front of the superficial medial collateral ligament to provide access to the anterior medial structures of the knee such as the medial meniscus anterior and cruciate ligament, while an incision is made posterior to the superficial medial collateral ligament to provide access to posteromedial structures such as the posterior medial meniscus. (3)
The proximal cut end of the infrapatellar branch of the saphenous nerve should be embedded in the adipose tissue because of the risk of neuroma formation. The saphenous nerve itself must be protected. While raising the medial head of the gastrocnemius posteriorly over the capsule, care should be taken in terms of injury to the inferior medial genicular artery and popliteal artery. It is important to have good bleeding control during surgery and to place a drainage tube after surgery to prevent post-operative hematoma formation. (3)
Lateral surgical approach; It provides access and intervention to the lateral support structures of the knee joint. It can be used for lateral collateral ligament repair, lateral meniscus repair or excision, and access to the lateral capsule. With the patient in the supine position on the operating table, with the knee joint in flexion position, a skin incision is made 3 cm lateral to the upper border of the patella in a curved manner towards the Gerdy tubercle. After excluding the skin and subcutaneous fat tissue as a flap, it is entered between the ilitibial band and biceps femoris muscles. When the biceps femoris muscle is retracted laterally with the peroneal nerve located just behind it, the superficial lateral collateral ligament (fibular collateral ligament) and posterolateral capsule are exposed. The joint is entered in front of and behind the superficial lateral collateral ligament. If it is entered from the front, the anterior and middle parts of the lateral meniscus can be seen. In case of entry from the back, it is necessary to enter between the lateral head of the gastrocnemius and the capsule to see the posterior horn. Under the lateral head of the gastrocnemius, the lateral superior genicular arteries should be located and ligated. It should also be noted that during this incision, the popliteus tendon is located just below the joint capsule. (3)
The structure most at risk during the lateral approach is the common peroneal nerve. It should be primarily found and protected during surgery. (3)
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