Faculty Bibliography

OBJECTIVE: Subchondroplasty is a novel minimally invasive procedure that is used to treat painful bone marrow lesions in patients with knee osteoarthritis or insufficiency fractures. The objective of this article is to describe the surgical technique and the pre- and postoperative imaging findings of a small case series acquired at a single center. CONCLUSION: The radiologist should be familiar with the anticipated postoperative imaging appearances after subchondroplasty and the potential complications.

The current study aimed to measure perioperative changes in driving performance following arthroscopic shoulder surgery using a validated driving simulator.21 patients who underwent arthroscopic surgery for rotator cuff or labral pathology were tested on a driving simulator preoperatively, and 6 and 12 weeks postoperatively. An additional 21 subjects were tested to establish driving data in a control cohort. The number of collisions, centerline crossings, and off-road excursions were recorded for each trial. VAS and SPADI scores were obtained at each visit.The mean number of collisions in the study group significantly increased from 2.05 preoperatively to 3.75 at 6 weeks (p<0.001), and significantly decreased to 1.95 at 12 weeks (p<0.001). Centerline crossings and off-road excursions did not significantly change from preoperative through 12 weeks, although centerline crossings were statistically different from the controls at each time point (p<0.001). Surgery on the dominant driving arm resulted in greater collisions at 6 weeks than surgery on the non-dominant driving arm (p<0.001).Preliminary data shows that driving performance is impaired for at least 6 weeks postoperatively, with a return to normal driving by 12 weeks. Driving is more profoundly affected in conditions that require avoiding a collision and when the dominant driving arm is involved.

PURPOSE: This study aims to study femoral tunnel lengths drilled with a flexible reamer and the distance to important lateral structures obtained by flexing the knee at various angles and by drilling the guide pins arthroscopically to resemble clinical practice. The purpose of this cadaveric study was twofold: 1. to determine whether femoral tunnel lengths of greater than 20 mm can be created with a flexible reamer system at 90 degrees of knee flexion and 2. to determine whether the lateral structures of the knee are safe with this technique. METHODS: Ten fresh cadaveric knees were utilized. The intra-osseous length can be measured with a specially de - signed flexible guide pin. Flexible pins were inserted with the knee at 70 degrees , 90 degrees , and 120 degrees of flexion. The intra-osseous length was measured with the measuring device. Each speci - men was dissected around the lateral aspect of the knee to identify the critical structures, the common peroneal nerve, and the LCL. The distance from the guide pins to the com - mon peroneal nerve and femoral attachment of the LCL were measured with a standard flexible paper ruler to the nearest millimeter. RESULTS: There is a trend for progressively increasing mean intra-osseous length associated with increased flexion of the knee. The mean intra-osseous length for 70 degrees flexion was 25.2 mm (20 mm to 32 mm), which was statistically significant when compared to mean intra-osseous lengths of 32.1 mm (22 mm to 45 mm) and 38.0 mm (34 mm to 45 mm) in the 90 degrees and 120 degrees flexion groups, respectively (p < 0.05). There were no significant differences among the groups with respect to distance to the LCL. There is a trend toward longer distances to the common peroneal nerve with increased flexion. There was a statistically significant dif - ference when comparing 120 degrees versus 70 degrees (p < 0.05). CONCLUSIONS: This study that shows that adequate femoral tunnel lengths can be safely created without knee hyperflex - ion using flexible instruments via an anteromedial portal.

Osteochondritis dissecans (OCD) of the capitellum is an articular cartilage lesion commonly affecting young adolescents. The exact mechanism for the development of these lesions is still uncertain; however, both traumatic and vascular etiologies have been described. Careful physical examination in conjunction with appropriate diagnostic studies helps the surgeon to classify these lesions as stable or unstable and leads to proper management. There is a diverse array of treatments available for OCD lesions of the capitellum, including fragment excision or fixation, bone marrow stimulation, and osteochondral autograft transplantation. This review helps the orthopaedic surgeon understand the diagnosis and management options available for OCD lesions of the capitellum.

OBJECTIVE: A discoid meniscus is more prone to tears than a normal meniscus. Patients with a torn discoid lateral meniscus are at increased risk for early onset osteoarthritis requiring total knee arthroplasty (TKA). Optimal management for this condition is controversial given the up-front cost difference between the two treatment options: the more expensive meniscal allograft transplantation compared with standard partial meniscectomy. We hypothesize that meniscal allograft transplantation following excision of a torn discoid lateral meniscus is more cost-effective compared with partial meniscectomy alone because allografts will extend the time to TKA. METHODS: A decision analytic Markov model was created to compare the cost effectiveness of two treatments for symptomatic, torn discoid lateral meniscus: meniscal allograft and partial meniscectomy. Probability estimates and event rates were derived from the scientific literature, and costs and benefits were discounted by 3%. One-way sensitivity analyses were performed to test model robustness. RESULTS: Over 25 years, the partial meniscectomy strategy cost $10,430, whereas meniscal allograft cost on average $4040 more, at $14,470. Partial meniscectomy postponed TKA an average of 12.5 years, compared with 17.30 years for meniscal allograft, an increase of 4.8 years. Allograft cost $842 per-year-gained in time to TKA. CONCLUSION: Meniscal allografts have been shown to reduce pain and improve function in patients with discoid lateral meniscus tears. Though more costly, meniscal allografts may be more effective than partial meniscectomy in delaying TKA in this model. Additional future long term clinical studies will provide more insight into optimal surgical options.

BACKGROUND: Considerable debate remains over which anterior cruciate ligament (ACL) reconstruction technique can best restore knee stability. Traditionally, femoral tunnel drilling has been done through a previously drilled tibial tunnel; however, potential nonanatomic tunnel placement can produce a vertical graft, which although it would restore sagittal stability, it would not control rotational stability. To address this, some suggest that the femoral tunnel be created independently of the tibial tunnel through the use of an anteromedial (AM) portal, but whether this results in a more anatomic footprint or in stability comparable to that of the intact contralateral knee still remains controversial. QUESTIONS/PURPOSES: (1) Does the AM technique achieve footprints closer to anatomic than the transtibial (TT) technique? (2) Does the AM technique result in stability equivalent to that of the intact contralateral knee? (3) Are there differences in patient-reported outcomes between the two techniques? METHODS: Twenty male patients who underwent a bone-patellar tendon-bone autograft were recruited for this study, 10 in the TT group and 10 in the AM group. Patients in each group were randomly selected from four surgeons at our institution with both groups demonstrating similar demographics. The type of procedure chosen for each patient was based on the preferred technique of the surgeon. Some surgeons exclusively used the TT technique, whereas other surgeons specifically used the AM technique. Surgeons had no input on which patients were chosen to participate in this study. Mean postoperative time was 13 +/- 2.8 and 15 +/- 3.2 months for the TT and AM groups, respectively. Patients were identified retrospectively as having either the TT or AM Technique from our institutional database. At followup, clinical outcome scores were gathered as well as the footprint placement and knee stability assessed. To assess the footprint placement and knee stability, three-dimensional surface models of the femur, tibia, and ACL were created from MRI scans. The femoral and tibial footprints of the ACL reconstruction as compared with the intact contralateral ACL were determined. In addition, the AP displacement and rotational displacement of the femur were determined. Lastly, as a secondary measurement of stability, KT-1000 measurements were obtained at the followup visit. An a priori sample size calculation indicated that with 2n = 20 patients, we could detect a difference of 1 mm with 80% power at p < 0.05. A Welch two-sample t-test (p < 0.05) was performed to determine differences in the footprint measurements, AP displacement, rotational displacement, and KT-1000 measurements between the TT and AM groups. We further used the confidence interval approach with 90% confidence intervals on the pairwise mean group differences using a Games-Howell post hoc test to assess equivalence between the TT and AM groups for the previously mentioned measures. RESULTS: The AM and TT techniques were the same in terms of footprint except in the distal-proximal location of the femur. The TT for the femoral footprint (DP%D) was 9% +/- 6%, whereas the AM was -1% +/- 13% (p = 0.04). The TT technique resulted in a more proximal footprint and therefore a more vertical graft compared with intact ACL. The AP displacement and rotation between groups were the same and clinical outcomes did not demonstrate a difference. CONCLUSIONS: Although the AM portal drilling may place the femoral footprint in a more anatomic position, clinical stability and outcomes may be similar as long as attempts are made at creating an anatomic position of the graft. LEVEL OF EVIDENCE: Level III, therapeutic study.

Bone marrow edema of the knee occurs secondary to a myriad of causes. The hallmark of a bone marrow lesion (BML) is an area of decreased signal intensity on T1 weighted MRI with a corresponding area of increased signal intensity on a T2 weighted MRI. Recently, chronic bone marrow lesions have been correlated with knee pain and progression of osteoarthritis. These lesions have also been associated with other degenerative conditions such as meniscal tears, cartilage deterioration, subchondral cyst formation, mechanical malalignment, and ultimately progression to arthroplasty. Medical treatments, such as prostacyclin and bisphosphonate therapy, have shown promise. Alignment procedures, as well as core decompression and subchondroplasty, have been used as surgical treatments for chronic BMLs.

INTRODUCTION: Recurrent patellar instability can be a source of continued pain and functional limitation in the young, active patient population. Instability in the setting of an elevated tibial tubercle-trochlear groove (TT-TG) distance can be effectively managed with a tibial tubercle osteotomy. At the present time, clinical outcome data are limited with respect to this surgical approach to patellar instability. METHODS: A retrospective chart review was performed to identify all cases of tibial tubercle osteotomy for the management of patellar instability performed at our institution with at least 1 year of post-operative follow-up. Patient demographic information was collected along with relevant operative data. Each patient was evaluated post-operatively with their outcomes assessed utilising a visual analogue score of pain, patient satisfaction, Tegner Activity Scale and Kujala score. RESULTS: 31 patients (23 females and 8 males) with mean age of 27 years (17-43 years) and a mean BMI of 26.3kg/m(2) (19.6-35.8) at time of surgery who underwent a tibial tubercle osteotomy as treatment for recurrent patellar instability were identified. The cohort had a mean follow up of 4.4 years (1.5-11.8 years). The mean pre-operative TT-TG distance was 18mm (10-22mm). The mean VAS pain score demonstrated a significant improvement from 6.8 (95% CI 6.1-7.5) at baseline to 2.8 (95% CI 1.9-3.7) post-operatively (p<0.001). The Tegner score improved from 4.1 (95% CI 3.4-4.8) pre-operatively to 5.2 (95% CI 4.5-5.9) at the time of final follow up (p<0.04). The Kujala score for anterior knee pain improved postoperatively from 62 (95% CI 55.4-68.7) to 76.5 (95% CI 69.5-83.5) at final follow up (p<0.001). 26 of the 31 patients (83.8%) had good to excellent Kujala scores. 27 of 31 patients (87.1%) reported that they would undergo the procedure again if necessary. CONCLUSION: For the management of recurrent patellar instability in the setting of an increased tibial tubercle-trochlear groove distance, a corrective tibial tubercle osteotomy is an effective treatment modality to reliably prevent patellar instability while reducing pain and improving function in this cohort of young, active patients.

PURPOSE: To evaluate the fixation integrity at time zero of a type I/III collagen patch secured to a chondral defect in the porcine knee using methods typically employed in autologous chondrocyte implantation (ACI) and matrix-assisted chondrocyte implantation. METHODS: Twenty-four porcine knee specimens underwent a medial parapatellar arthrotomy. A prefabricated template was used to create cartilage defects of 2 cm2 in the medial femoral condyle. A size-matched collagen patch was fashioned. Four methods of fixation to the chondral defect were analyzed: group 1-saline, group 2-fibrin glue around the periphery of the patch, group 3-fibrin glue applied to the base of the defect and around the periphery of the patch, group 4-6-0 vicryl suture and fibrin glue around the periphery of the patch. Collagen patch fixation was assessed at intervals of 60, 300, 600, 900, and 1,200 cycles from full extension to 90 degrees of flexion, performed manually without application of axial force. Patch fixation was evaluated by 2 independent observers using a customized scoring scale. RESULTS: Mean peripheral detachment of the patch and chondral defect uncovering remained less than 25% for all groups. Area of defect uncovering was significantly increased in group 2 compared with group 4 after 900 and 1,200 cycles (P = .0014 and P = .0025, respectively). Fibrin glue applied to the base of the defect, or suturing of the patch, reduced deformation significantly after 900 cycles. CONCLUSIONS: Suture increases the stability of fixation of a type I/III collagen patch to a chondral defect better than fibrin glue alone in the porcine knee after repetitive cycling, with respect to patch detachment and chondral defect uncovering. Application of fibrin glue to the base of the defect, or securing the patch with suture, decreases collagen patch deformation. CLINICAL RELEVANCE: In cases where minimally invasive techniques do not allow suture fixation of the collagen patch, scaffold fixation may be compromised during articular motion protocols typically used after second- and third-generation ACI procedures.