Working Diagnosis:
The MRI of the Left Knee indicated an anterior cruciate ligament tear, complex tear of the posterior horn of the lateral meniscal (hemi bucket-handle), evidence of transient patellar dislocation, Grade 1 LCL/MCL sprain, tenosynovitis of the sartorius tendon, tendinosis of patellar and quadriceps tendon with edema of the medial patellar retinaculum.

Treatment:
Non-operative and operative management options were discussed and provided to the patient. He initially used a functional hinged-knee immobilizer and crutches to assist with ambulation. Oral and topical NSAID's were provided as well instructions for local cryotherapy. On MRI, the patella was located in normal position and minimal cartilage injury was noted. As this was his first dislocation, he was at low risk for re-dislocation. The patient had been sent for rehabilitation for about 1 month prior to surgery to ensure patellar stabilization over time and to regain full knee ROM. The Orthopedic Surgeon chose a Bone-Tendon-Bone (BTB) graft because this provides patellar stability secondary to adhesions that develop with BTB more than a hamstring autograft. Furthermore, intra-operatively, the patella was stable during dynamic arthroscopic exam, and minimal chondral injury was noted.

Outcome:
The patient has a stable patella, full ROM and is using an ACL brace with the anticipation to initiate regular activities.

Author's Comments:
Acute knee pain following a traumatic event can have multiple pathologies and typically results in one or more internal derangements of the knee. In this case, the event caused damage to multiple structures. Physical examination assists in diagnosis and identifying treatment options, though ultimately, an MRI was crucial for an accurate diagnosis. Although non-operative treatment can be undergone, most individuals and athletes chose a surgical option for improved recovery.

Editor's Comments:
The ACL is the primary stabilizer against anterior tibial translation. Non-contact tears of the ACL often occur during rapid deceleration, e.g. landing from a jump. Several types of grafts are used for reconstruction. Graft choice may be influenced by specific factors, such as age and concomitant injury. For example, BTB grafting may better preserve the medial stabilizing role of the hamstring tendons in those with a grade 3 MCL injury.1

Many studies, including the MOON cohort2, show an increased failure rate when allografts are used in young, active individuals. For this reason, BTB and hamstring autografts are often preferred. Outcome data pertaining to ACL graft type among those with combined ACL rupture and patellar instability is not available.

At 5 years post ACL reconstruction, Mohtadi and Chan3 compared outcomes among those with BTB and hamstring grafts. Subjective IKDC scores and risk of extension deficits were similar. Rerupture occurred less frequently with BTB. Objective IKDC scores trended towards favoring BTB, but anterior knee pain occurred more often with BTB.

Not all studies show an increased risk of rerupture for hamstring vs. BTB grafts.2 Long-term outcomes may depend more upon surgical technique, patient selection, and identification of concomitant injuries than upon the choice of graft.4

References:
Kremen TJ, Polakof LS, Rajaee SS et al. The Effect of Hamstring Tendon Autograft Harvest on the Restoration of Knee Stability in the Setting of Concurrent Anterior Cruciate Ligament and Medial Collateral Ligament Injuries. Am J Sports Med. 2018;46(1):163-170.
Kaeding C.C., Pedroza A.D., Reinke E.K., et. al.: Risk factors and predictors of subsequent ACL injury in either knee after ACL reconstruction: prospective analysis of 2488 primary ACL reconstructions from the MOON cohort. Am J Sports Med 2015; 43: pp. 1583-1590.
Mohtadi N, Chan D. A Randomized Clinical Trial Comparing Patellar Tendon, Hamstring Tendon, and Double-Bundle ACL Reconstructions. JBJS. 2019;101:049-60.
Thaunat M, Fayard JM, Sonnery-Cottet B. Hamstring tendons or bone-patellar tendon-bone graft for anterior cruciate ligament reconstruction? Orthop Traumatol Surg Res. 2019 Feb;105(1S):S89-S94. doi: 10.1016/j.otsr.2018.05.014.

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