The use of antibiotic resistance analysis (ARA) for microbial source tracking requires the generation of a library of isolates collected from known sources in the watershed. The size and composition of the library are critical in determining if it represents the diversity of patterns found in the watershed. This study was performed to determine the size that an ARA library needs to be to be representative of the watersheds for which it will be used and to determine if libraries from different watersheds can be merged to create multiwatershed libraries. Fecal samples from known human, domesticated, and wild animal sources were collected from six Virginia watersheds. From these samples, enterococci were isolated and tested by ARA. Based on cross-validation discriminant analysis, only the largest of the libraries (2,931 isolates) were found to be able to classify nonlibrary isolates as well as library isolates (i.e., were representative). Small libraries tended to have higher average rates of correct classification, but were much less able to correctly classify nonlibrary isolates. A merged multiwatershed library (6,587 isolates) was created and was found to be large enough to be representative of the isolates from the contributing watersheds. When isolates that were collected from the contributing watersheds approximately 1 year later were analyzed with the multiwatershed library, they were classified as well as the isolates in the library, suggesting that the resistance patterns are temporally stable for at least 1 year. The ability to obtain a representative, temporally stable library demonstrates that ARA can be used to identify sources of fecal pollution in natural waters.

Background: Patients who are refractory to initial management of trochlear dysplasia, which consists of bracing and physical therapy, may be candidates for trochleoplasty. Indications: Indications for trochleoplasty include Dejour classification type B or D trochlear dysplasia, supratrochlear spur height ≥7 mm, and a positive J sign on examination. Technique Description: The thick shell sulcus-deepening trochleoplasty technique involves removing the supratrochlear spur by creating a 5-mm–thick osteochondral shell with underlying cavity, dividing the thick shell into medial and lateral leaflets, and securing the leaflets with absorbable sutures. This establishes a new trochlear groove that is flush with the anterior cortex of the femur. Results: A review of 21 studies with length of follow-up from 8.8 months to 15 years found postoperative dislocation was present in 0% to 15% of patients and the patient satisfaction ranged from 81.0% to 94.4%. A prospective study with a minimum 2-year follow-up found no cases of recurrent dislocation, no progression of radiographic arthritis, 84.8% of patients returned to sport, and the patient satisfaction was a 9.1/10. Discussion/Conclusion: Sulcus-deepening trochleoplasty for trochlear dysplasia provides patellar stability and excellent patient satisfaction.

Background: This technique video reviews an iliotibial band Z-lengthening procedure for iliotibial band (ITB) syndrome using a patient case example. Indications: Indications for considering surgical intervention include a diagnosis of iliotibial band syndrome, ruling out other possible etiologies of knee pain, and a minimum of 6 months of failed conservative treatment. Technique Description: There are several surgical techniques described in the literature, although the ITB Z-lengthening procedure is preferred at our institution. This technique uses a “Z”-type incision through the distal ITB to allow lengthening of the ITB and to allow access for surgical debridement of the underlying inflamed bursa. Nonabsorbable suture is then used for a side-to-side repair of the ITB in the elongated position. Results: Complications from this technique are uncommon, and the few published outcomes from this procedure show good clinical results and return to preactivity levels. Discussion/Conclusion: Preoperative planning should include analysis of lower extremity alignment and can include advanced imaging to rule out intra-articular pathology. Diagnostic arthroscopy is typically used at the start of the case for completeness. Distal iliotibial band Z-lenghtening can be a successful surgical option for patients who have failed extensive conservative treatment for iliotibial band syndrome.

Background: Graft-tunnel mismatch (GTM) is a common problem in anterior cruciate ligament (ACL) reconstruction (ACLR) using bone–patellar tendon–bone (BPTB) grafts. Hypothesis: Application of the “N+10 rule” in endoscopic ACLR with BPTB grafts will result in acceptable tibial tunnel length (TTL), minimizing GTM. Study Design: Controlled laboratory study. Methods: Endoscopic BPTB ACLR was conducted on the paired knees of 10 cadaveric specimens using 2 independent femoral tunnel drilling techniques—accessory anteromedial portal and flexible reamer. The graft bone blocks were trimmed to 10 × 20 mm, and the intertendinous distance (represented by “N”) between the bone blocks was measured. The N+10 rule was used to set the angle of the ACL tibial tunnel guide to the appropriate number of degrees for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A GTM threshold of ±7.5 mm was set based on prior studies. Results: The mean BPTB ACL intertendinous distance was 47.5 ± 5.5 mm. The mean measured intra-articular distance was 27.2 ± 3 mm. Using the N+10 rule, the mean total (flexion plus extension) GTM was 4.3 ± 3.2 mm (GTM in flexion, 4.9 ± 3.6 mm; GTM in extension, 3.8 ± 3.5 mm). In 18 of 20 (90%) cadaveric knees, the mean total GTM fell within the ±7.5-mm threshold. When comparing the actual measured TTL to the calculated TTL, there was a mean difference of 5.4 ± 3.9 mm. When comparing femoral tunnel drilling techniques, the total GTM for the accessory anteromedial portal technique was 2.1 ± 3.7 mm, while the total GTM for the flexible reamer technique was 3.6 ± 5.4 mm ( P = .5). Conclusion: The N+10 rule resulted in an acceptable mean GTM in both flexion and extension. The mean difference between the measured versus calculated TTL using the N+10 rule was also acceptable. Clinical Relevance: The N+10 rule is a simple and effective intraoperative strategy for achieving desired TTL regardless of patient-specific factors to avoid excessive GTM in endoscopic BPTB ACLR using independent femoral tunnel drilling.

Background: Tibial tubercle osteotomy and distal realignment allows for adjustment to the patellofemoral articulation in order to improve patellar tracking and redistribute patellar contract pressures. Indications: A healthy, active 39-year-old woman status post right knee tibial tubercle osteotomy presented with >2 years of patellar instability symptoms in the left knee. Imaging revealed a tibial tubercle to trochlear groove (TT-TG) distance of 21 mm and patellar tendon lateral trochlear ridge (PT-LTR) distance of 14 mm. Technique Description: After knee arthroscopy is performed, an open incision is made along the inferomedial patellar tendon. Two pilot holes are created before a sagittal saw is used to make the tibial tubercle osteotomy, before completing it with an osteotome. Anteromedialization and/or distalization of the osteotomy is performed relative to templated values in order to improve patellar articulation. After correction, 3 bicortical screws are placed to achieve stable fixation. Results: There were no immediate complications following surgery. Surgical management led to improvement of the patient’s patellofemoral pain, which allowed return to prior baseline level of function. Discussion/Conclusion: The preferred technique for an anteromedialzing tibial tubercle osteotomy is presented. An anteromedializing tibial tubercle osteotomy is an effective surgical option for patients with evidence of patellar maltracking or central or lateral patellar chondromalacia whom have failed conservative management. This case demonstrates the efficacy of an anteromedializing tibial tubercle osteotomy to provide pain relief by improving patellar tracking and offloading patellar contact pressures on areas of prominent chondral wear.