Complex Patellofemoral Reconstruction for Recurrent Instability

Background: Patellofemoral instability is due to a combination of bony and soft tissue factors. While recurrent patellar dislocations are rare, evaluation and treatment of these conditions require addressing patellar height and lateralization of the tibial tubercle (TT), restraint to lateral patellar subluxation, and trochlear dysplasia. Other factors to consider are coronal limb-length alignment outside of the physiologic 5 to 8° of valgus, which may significantly alter the Q angle and contribute to lateral instability. Other ligaments around the patella contribute to soft-tissue restraint, including the medial and lateral patellotibial ligaments, patellomeniscal ligaments, and the medial quadriceps tendon femoral ligament. Patellar tilt is assessed with and without quadriceps contraction to further evaluate the patella’s relationship to the trochlear groove. The Caton-Deschamps Index, as well as patellar trochlear index (PTI), are used to measure patellar height for patella alta or baja. Technique Description: The technique is to surgically manage a patient in neutral mechanical alignment on standing limb radiographs, with moderate-to-severe DeJour type B trochlear dysplasia and a trochlear sulcus angle of around 145°, patella alta with a Caton-Deschamps Index of 1.6 and PTI of 0.22, a TT to trochlear groove (TT-TG) distance of 8 mm, and a deficient medial patellofemoral ligament (MPFL). The MPFL reconstruction is done first, with harvesting of the ipsilateral quadriceps tendon and maintenance of its distal attachment on the superior patellar pole. The quadriceps tendon graft is folded medially upon its distal attachment and fixed in this position with suture anchors. Tibial tubercle osteotomy is accomplished by spacing drill holes 2 mm apart, medially and laterally, on the TT and connecting the drill holes with an osteotome and reciprocating saw. A distalized location to secure the TT is selected and superficial bone is excised. A medial parapatellar arthrotomy is performed, and bur attachments are used to drill into the subchondral bone beneath the femoral articular surface to create a V-shaped flap of trochlear cartilage. An arthroscope is inserted under the trochlear flap during this process to visualize the appropriate depth. The trochlear flap is then secured with screws passed over guide pins to secure the flap to the desired location. Cannulated screws and washers are then used to secure the TT to its distalized and/or medialized position, with fluoroscopic verification of screw depth and location. The arthrotomy is then closed with the knee at 45°. The quadriceps graft is passed through a subretinacular channel and secured with suture anchors, adjacent to the adductor tubercle, to complete the MPFL reconstruction. Before closure, appropriate tracking and translation of the patella is verified. Results: Sulcus-deepening trochleoplasty, with or without MPFL reconstruction, has been reported to obtain satisfactory outcomes at 2 years, with close to 85% return to sport and 100% return to work, with improvements in International Knee Documentation Committee (IKDC) scores from 50.8 to 79.1 in some studies. MPFL reconstruction with tibial tubercle osteotomy (TTO) has yielded a 94.5% patient satisfaction rate in the literature. Discussion/Conclusion: In patients with recurrent patellar instability and DeJour types B-D trochlear dysplasia, MPFL reconstruction with TTO and sulcus-deepening trochleoplasty provides excellent subjective outcomes and restores patellar tracking with elimination of recurrent subluxation.

Predicting Diameter Increase Using a Quadriceps Tendon Augmentation for Undersized Hamstring Grafts in ACL Reconstruction

Background The failure rate for ACL reconstruction varies between 5 to 25% depending on the population. Recent studies found a higher failure rate with grafts of 8 millimeters in diameter or less. Various options are described when the graft’s diameter is inferior to the target value, but little literature helps us predict the final diameter during surgeries. Therefore, this study’s goal is to describe a new technique supplementing a hamstring graft folded in half with a quadricipital tendon band of partial width and thickness (4S+Q), and to predict the final diameter. Methods Thirty-three cadaveric knees were dissected in order to harvest semitendinosus and gracilis tendons (4S) along with a 6mm wide tendon band from the rectus femoris. Harvesting was done according to the usual surgical technique. Measures of length and diameter in 4S and 4S+Q configurations were performed separately by three evaluators. Results The threshold diameter of 8,5 mm was attained in only 30% of 4S grafts within our population in comparison with 88% when augmented with a quadriceps band. The average diameter increase with the 4S+Q configuration was 1,49 mm. A threshold of 7,5 mm was established for the applicability of this augmentation technique considering that 93% of the grafts measuring 7,5 mm or more reached the 8,5mm target. Conclusions The 4S+Q configuration offers a salvage option worth adding to one’s arsenal, significantly increasing the graft’s diameter. The width of the quadricipital tendon sample can be adjusted and will need further study.

Influence of the Amount of Change in Quadriceps Tendon Young’s Modulus on Amount of Change in Walking Speed before and after Total Knee Arthroplasty

Background and Objectives: Walking speed after total knee arthroplasty (TKA) is an important outcome. However, the effect of quadriceps tendon stiffness on walking speed remains unclear. This study aimed to clarify the influence of the amount of change in quadriceps tendon stiffness on the degree of change in walking speed before and after TKA. Materials and Methods: Sixteen patients who underwent TKA for knee osteoarthritis participated in this study (median age: 74.0 years (interquartile range: 64.5–75.8)). Shear-wave elastography was deployed to measure quadriceps tendon stiffness using Young’s modulus. A motion analysis system was used to assess kinematic parameters and walking speed. Participants’ knee circumference, range of motion, extension strength, one-leg standing time, walking pain level, and activity level were measured preoperatively and one year after TKA, and changes in values were calculated. We used path analysis to clarify the influence of the amount of change in the quadriceps tendon Young’s modulus on the change in walking speed. Results: The quadriceps tendon Young’s modulus negatively affected the knee flexion angle during swing (standardized partial regression coefficients (β) = −0.513, p = 0.042). The knee flexion angle during swing positively affected step length (β = 0.586, p = 0.017). Step length positively affected cadence (β = 0.733, p = 0.001). Step length and cadence positively affected walking speed (β = 0.563, p < 0.001, β = 0.502, p < 0.001, respectively). Conclusions: The amount of change in the quadriceps tendon Young’s modulus may affect the degree of change in walking speed after TKA through the amount of change in the knee flexion angle during swing, step length, and cadence. Clinically, reducing quadriceps tendon stiffness can be addressed in rehabilitation programs to increase walking speed after TKA.

Quadriceps Tendon Autograft in Pediatric ACL Reconstruction: Graft Dimensions and Prediction of Size on Preoperative MRI

Background: There is increased interest in quadriceps autograft anterior cruciate ligament (ACL) reconstruction in the pediatric population. Purpose: To evaluate children and adolescents who underwent ACL reconstruction using a quadriceps autograft to determine the properties of the harvested graft and to assess the value of demographic, anthropometric, and magnetic resonance imaging (MRI) measurements in predicting the graft size preoperatively. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A retrospective database search was performed from January 2018 through October 2020 for patients undergoing ACL reconstruction. Patients <18 years old at the time of surgery in whom a quadriceps tendon autograft was used were selected. Demographic data and anthropometric measurements were recorded, and graft measurements were abstracted from the operative notes. Knee MRI scans were reviewed to measure the quadriceps tendon thickness on sagittal cuts. Graft length and diameter were then correlated with anthropometric and radiographic data. Results: A total of 169 patients (98 male) were included in the final analysis, with a median age of 15 years (range, 9-17 years). A tendon length ≥65 mm was harvested in 159 (94%) patients. The final graft diameter was 8.4 ± 0.7 mm (mean ± SD; range, 7-11 mm). All patients had a graft diameter ≥7 mm, and 139 (82%) had a diameter ≥8 mm. Preconditioning decreased the graft diameter by a mean 0.67 ± 0.23 mm. Age ( P = .04) and quadriceps thickness on MRI ( P = .003) were significant predictors of the final graft diameter. An MRI sagittal thickness >6.7 mm was 97.4% sensitive for obtaining a graft ≥8 mm in diameter. Conclusion: Our findings suggest that tendon-only quadriceps autograft is a reliable graft source in pediatric ACL reconstruction, yielding a graft diameter ≥8 mm in 82% of pediatric patients. Furthermore, preoperative MRI measurements can be reliably used to predict a graft of adequate diameter in children and adolescents undergoing ACL reconstruction, with a sagittal thickness >6.7 mm being highly predictive of a final graft size ≥8 mm.