Treatment of medial knee injuries varies depending on location and classification of the injuries. The consensus of many studies is that isolated grade I, II, and III injuries are usually well suited to non-operative treatment protocols. Acute grade III injuries with concomitant multiligament injuries or knee dislocation involving medial side injury should undergo surgical treatment. Chronic grade III injuries should also undergo surgical treatment if the patient is experiencing rotational instability or side-to-side instability.
Nonoperative treatment Conservative treatment of isolated medial knee injuries (grades I-III) begins with controlling swelling and protecting the knee. Swelling is managed well with rest, ice, elevation, and compression wraps. Protection can be performed using a hinged brace that stabilizes against
varus and
valgus stress but allows full flexion and extension. The brace should be worn for the first four to six weeks of
rehabilitation, especially during physical exercise to prevent trauma to the healing ligament. Stationary bike exercises are the recommended exercise for active range of motion and should be increased as tolerated by the patient. Side-to-side movements of the knee should be avoided. The patient is allowed to bear weight as tolerated and should perform
quadriceps strengthening exercises along with
range of motion exercises. The typical return-to-play time frame for most athletes with a grade III medial knee injury undergoing a rehabilitation program is 5 to 7 weeks.
Operative treatment It has been reported that severe acute and chronic grade III medial knee injuries often involve the sMCL in combination with the POL. Direct surgical repair or reconstruction, therefore, should be performed for both of these ligaments because they both play an important role in static medial knee stability. The
biomechanically validated approach is to reconstruct both the POL and both divisions of the sMCL.
Severe acute tears Surgery involving direct repair (with or without augmentation from a
hamstring autograft), among other previously used techniques, have not been biomechanically tested. An anatomical reconstruction of the sMCL and POL has been biomechanically validated.
Chronic instability Underlying causes of chronic medial knee instability must be identified before surgical reconstruction is performed. More specifically, patients with
genu valgum (knock-kneed) alignment must be evaluated and treated with an
osteotomy(s) to establish balanced forces on knee ligaments, preventing premature failure of concurrent cruciate ligament reconstruction. These patients should be rehabilitated after the osteotomy heals before it can be verified that they do not still have functional limitations. Once proper alignment is achieved, reconstruction can be performed.
Anatomic medial knee reconstruction This technique, described in detail by LaPrade et al., uses two
grafts in four separate tunnels. An incision is made over the medial knee 4 cm medial to the patella, and extended distally 7 to 8 cm past the joint line, directly over the
pes anserinus tendons. Within the
distal borders of the incision, the
semitendinosus and
gracilis tendons are found beneath the
sartorius muscle fascia. The distal
tibial attachment of the sMCL can be found under these identified tendons, making up the floor of the pes anserine bursa, 6 cm distal to the joint line. Once identified, the remaining soft tissue is removed from the attachment site. An eyelet pin is then drilled through attachment site transversely through the tibia, making sure the starting point is located at the posterior aspect of the site to ensure better
biomechanical outcomes. Over the eyelet pin, a 7-mm reamer (6 mm considered in smaller patients) is reamed to a depth of 25 mm. Once prepared, attention is directed to preparing the reconstruction tunnel for the tibial attachment of the POL. Above the
anterior arm attachment of the semimembranosus muscle tendon, the tibial attachment of the central arm of the POL is identified. This attachment is exposed by making a small incision parallel to the fibers along the posterior edge of the anterior arm of the semimembranosus tendon. Once exposed, an eyelet pin is drilled through the tibia toward
Gerdy's tubercle (anterolateral tibia). After verifying the correct anatomic eyelet pin placement, a 7-mm
reamer is used over the pin to drill a tunnel depth of 25 mm. Moving to the femoral attachments of the ligaments, the first step is identifying the
adductor magnus muscle tendon, and its corresponding attachment site, near the adductor tubercle. Just distal and slightly anterior to this tubercle is the bony prominence of the medial
epicondyle. The attachment site of the sMCL can be identified slightly
proximal and posterior to the epicondyle. An eyelet pin can now be passed transversely through the femur at this site. The tunnel at this location, however, should be drilled after identifying the POL attachment site. The next step of identifying the POL femoral attachment is done by locating the
gastrocnemius tubercle (2.6 mm distal and 3.1 mm anterior to the medial gastrocnemius tendon attachment on the femur). If the posteromedial capsule is not intact, the POL attachment site is located 7.7 mm distal and 2.9 mm anterior to the gastrocnemius tubercle. With the capsule intact, however, an incision is made along the posterior aspect of the sMCL, parallel to its fibers. The central arm of the POL can then be found at its femoral attachment site. Once identified, an eyelet pin is passed transversely through the femur. The distances between the femoral attachment site of the POL and the sMCL (on average, 11mm) should now be measured to verify that the anatomic attachment sites have been correctly identified. Once this is done, the femoral tunnels for the sMCL and POL can be reamed to a depth of 25 mm using a 7-mm reamer. The next aspect of the surgery is preparation and placement of the reconstruction grafts. The preparation can be done while the other steps are being completed by another surgeon or physician's assistant. The semitendinosus tendon can be harvested using a hamstring stripper for use as the reconstruction autograft. The autograft is sectioned into a 16-cm length for the sMCL reconstruction and 12-cm length for the POL reconstruction. These lengths are also used if the surgery is done with
cadaver allograft. The sMCL and POL grafts are pulled into their respective femoral tunnels and each secured with a
cannulated bioabsorbable
screw. The grafts are passed distally along their native courses to the tibial attachments. The sMCL is passed under sartorius fascia (and any remaining sMCL fibers). Both grafts are passed (but not yet secured) into their respective tibial tunnels using the existing eyelet pins. If simultaneous cruciate ligament surgery is underway, the cruciate reconstructions are secured before securing the medial ligaments. Securing the POL graft is done in full knee extension. The graft is pulled tight and fixed using a bioabsorbable screw. The knee is then flexed to 20°. Making sure the tibia remains in neutral rotation, a varus force is used to ensure there is no medial compartment gapping of the knee. The sMCL graft is then tightened and fixed with a bioabsorbable screw. The final step of reconstruction ligament fixation is the proximal tibial attachment of the sMCL. This
soft-tissue attachment can be reproduced with a
suture anchor placed 12.2 mm distal to the medial joint line (average location), directly medial to the anterior arm of the semimembranosus tibial attachment. Once this aspect of the sMCL is secured to the suture anchor, the knee is put through range of motion testing by the physician to determine the "safe zone" of knee motion which is used during the first
post-operative day rehabilitation (below). ==Rehabilitation==