Background: Anterior cruciate ligament reconstruction (ACLR) is a common orthopaedic sports medicine procedure, but graft failure is not uncommon and often leads to revision ACLR. Revision surgery can be performed in a 1- or 2-stage fashion. Hypothesis: Graft failure risk, patient-reported outcomes, and anterior knee laxity are similar after 1- and 2-stage revision ACLR. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature was performed to evaluate patient outcomes after 1- versus 2-stage revision ACLR. A search was performed with the phrase “revision anterior cruciate ligament reconstruction” across Embase, PubMed, Scopus, and SportDiscus from the beginning of their archives through July 12, 2019. Results: Thirteen studies met inclusion criteria and included 524 patients: 319 patients who underwent 1-stage revision ACLR and 205 patients who underwent 2-stage revision ACLR. Two studies compared outcomes of 1- versus 2-stage revision ACLR; 4 studies reported outcomes after 2-stage revision ACLR; and the remaining 7 studies documented outcomes after 1-stage ACLR. The mean follow-up was 4.1 years. The 2 studies that compared 1- versus 2-stage ACLR reported no differences in functional, radiologic, or patient-reported outcomes or failure risk. Overall, 9 studies reported subjective International Knee Documentation Committee (IKDC) scores; 4 studies, Knee injury and Osteoarthritis Outcome Score values; 8 studies, Lysholm scores; and 7 studies, Tegner scores; 8 studies measured anterior laxity with a KT-1000 arthrometer. The mean weighted subjective IKDC score for all studies including this outcome at final follow-up was 66.6 for 1-stage revisions and 65.9 for 2-stage revisions. Conclusion: The available evidence comparing 1- versus 2-stage revision ACLR is retrospective and limited. The results of each approach are similar in appropriately selected patients.

Background: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle–trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as tibial tubercle osteotomy or trochleoplasty. The indications to perform such procedures are traditionally based on imaging criteria but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. Hypothesis: The persistence of patellar apprehension at greater than 60° of knee flexion is associated with patella alta, an increased TT-TG distance, and trochlear dysplasia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 76 patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeatedly assessed as the knee was flexed in 10° intervals, as measured using a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain radiographs and magnetic resonance imaging (MRI) scans were obtained for all patients. Patellar height was assessed with the Caton-Deschamps (CD) index, and trochlear morphology was assessed through measurements of the sulcus angle and depth on MRI and classified using the Dejour classification system. Imaging measurements of patients in whom apprehension resolved by 60° of knee flexion were compared with measurements for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60° of flexion in 56 patients and persisted into deeper flexion in 20 patients. The patients with a delayed resolution of apprehension demonstrated a higher CD index; elevated TT-TG distance; increased sulcus angle; decreased sulcus depth; and higher incidence of Dejour type B, C, or D dysplasia (all P < .05). Of the 20 patients with a delayed resolution of apprehension, 18 had either Dejour type B, C, or D dysplasia or a CD index of at least 1.30. A delayed resolution of apprehension was present in 11 of the 16 patients with Dejour type B, C, or D dysplasia. Conclusion: Overall, 90% of patients with significant patella alta and the majority of patients with high-grade trochlear dysplasia demonstrated patellar apprehension that persisted beyond 60° of knee flexion. Additionally, 90% of patients with persistent apprehension had significant patella alta and/or trochlear dysplasia. Further work is needed to evaluate the utility of these findings to inform surgical decision-making in this population.

We hypothesize that larger prior tunnel size is associated with an increased risk of failure of single-stage revision anterior cruciate ligament reconstruction (ACLR) as defined by the performance of a re-revision (third) ACLR on the index knee. Retrospective review identified 244 patients who underwent single-stage revision ACLR at a single center with available preoperative radiographs. Patient and surgical factors were extracted by chart review. The maximum diameter of the tibial tunnel was measured on lateral radiographs and the maximum diameter of the femoral tunnel was measured on anteroposterior radiographs. Record review and follow-up phone calls were used to identify failure of the revision surgery as defined by re-revision ACLR on the index knee. One hundred and seventy-one patients (70%) were reviewed with a mean of 3.9 years follow-up. Overall, 23 patients (13.4%) underwent re-revision surgery. Mean tibial tunnel size was 12.6 ± 2.8 mm (range: 5.7–26.9 mm) and mean femoral tunnel size was 11.7 ± 2.8 mm (range: 6.0–23.0 mm). Re-revision risk increased with tibial tunnel size. Tibial tunnels 11 mm and under had a re-revision risk of 4.2%, while tunnels > 11 mm had a risk of 17.1% (relative risk: 4.1, p = 0.025). No significant association between femoral tunnel size and re-revision risk was noted. Patients with prior tibial tunnels > 11mm in diameter at revision surgery had significantly increased risk of re-revision ACLR. Further studies are needed to explore the relationship between prior tunnel size and outcomes of revision ACLR.

Objectives: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle-trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as a tibial tubercle osteotomy or trochleoplasty. The indications to include such procedures are traditionally based on imaging criteria, but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. We hypothesis that the persistence of patellar apprehension at greater than 60 degrees of knee flexion is associated with patella alta, increased TT-TG distance, and trochlear dysplasia. Methods: Seventy-six patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeated assessed as the knee was flexed in 10 degrees intervals as measured with a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain films and MRI were obtained in all patients. Patellar height was assessed with the Caton-Deschamps (CD) index and trochlear morphology was assessed through measurement of the sulcus angle and depth on MRI and classification with the Dejour classification system. Imaging measurements of patients in which apprehension resolved by 60 degrees of knee flexion were compared with measures for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60 degrees of flexion in 55 patients and persisted into deeper flexion in 21 patients. The patients with delayed resolution of apprehension demonstrated a higher CD Index, elevated TT-TG distance, increased higher sulcus angle, decreased trochlear depth, and a higher incidence of Dejour B, C, or D dysplasia (all p < 0.05, Table 1). Of the 21 patients with delayed resolution of apprehension, 18 had either Dejour B, C, or D dysplasia or a Caton-Deschamps Index of at least 1.3. Delayed resolution of apprehension was present in 11 of the 16 patients with Dejour B, C, or D dysplasia. Conclusion: The presence of patellar apprehension in higher degrees of knee flexion is associated with patella alta, increased TT-TG distance, and more severe trochlear dysplasia. Further work is needed to evaluate utility of this exam finding to inform surgical decision-making in this population.