Orthopedics

Lo, E.Y., Rizkalla, J., Montemaggi, P., Majekodunmi, T. and Krishnan, S.G. (2020). “Clinical and Radiographic Outcomes of Cementless Reverse Total Shoulder Arthroplasty for Proximal Humeral Fractures.” J Shoulder Elbow Surg Dec 23;S1058-2746(20)30930-7. [Epub ahead of print].

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INTRODUCTION: Reverse total shoulder arthroplasty (RTSA) has demonstrated successful outcomes in the treatment of both the acute and chronic proximal humerus fractures (PHFx). Traditional RTSA surgical technique utilizes a methyl methacrylate cemented humeral component to restore and maintain both humeral height and retroversion. However, use of humeral bone cement has been associated intraoperatively with cardiopulmonary risk, increased operative cost, and postoperatively with difficulty if revision arthroplasty is required. Here we report clinical and radiographic outcomes of a completely cementless RTSA technique for PHFx surgery. METHODS: Between 2013 and 2018, 60 consecutive patients underwent surgical management of a PHFx with cementless RTSA. All surgeries were performed by a single senior shoulder surgeon using a modified deltopectoral approach and a completely uncemented RTSA technique. Fractures were defined as “acute” and “chronic” based on a 4-week injury-to surgery benchmark. Mean age was 67 years (range 47-85 years). There were 18 acute fractures and 42 chronic fractures. Mean time from injury to surgery for acute fractures was 2 weeks (range 0.4-4) and chronic fractures was 60 months (range 1-482). Seventeen cases were excluded from postoperative evaluation due to revision, lost to follow-up, or both. All remaining 43 underwent clinical and radiographic evaluation by two independent fellowship-trained shoulder surgeons at mean 21 months postoperatively (Range 10-46). Independent statistical analysis was performed using paired t-test and Wilcoxon signed-rank test. RESULTS: At final review, mean active anterior elevation was 157° (range 100-170°), active external rotation 52° (range 6-80°), and active internal rotation 66° (range 0-80°). Improvements were seen in visual analog pain score (6-0.2, p<0.001), Simple Shoulder Test (SST) (9-93, p<0.001), American Shoulder and Elbow Surgeons (ASES) (19- 91, p<0.001), and Single-Assessment Numeral Evaluation (SANE) scores (21% - 89%, p<0.001). Overall, 39 of 43 (91%) of greater tuberosities demonstrated osseous healing to the humeral shaft. There were no significant differences in clinical and radiographic outcomes in acute vs chronic cases, and cases with minimum 1-year vs 2-year follow-up. Overall, there were 4 major complications necessitating surgical revision (6.7%), and no case of aseptic humeral stem loosening. CONCLUSION: Cementless RTSA for acute and chronic PHFx demonstrates clinical and radiographic outcomes similar to traditional cemented RTSA. The successful greater tuberosity healing and absence of humeral stem loosening in this short-term cohort are encouraging for continued long-term success of this technique. By avoiding cemented humeral implants, surgeons may minimize intraoperative complications, operative cost, and postoperative revision difficulty.

Harris, M.C., Hedrick, B.N., Zide, J.R., Thomas, D.M., Shivers, C., Seibert, M., Pierce, W.A., Kanaan, Y. and Riccio, A.I. (2020). “Effect of Lateral Column Lengthening on Subtalar Motion in a Cadaveric Model[Formula: see text].” Foot Ankle Int Nov 17;1071100720970189. [Epub ahead of print.]. 1071100720970189.

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BACKGROUND: Although lengthening of the lateral column through a calcaneal neck osteotomy is an integral component of flatfoot reconstruction in younger patients with flexible planovalgus deformities, concern exists as to the effect of this intra-articular osteotomy on subtalar motion. The purpose of this study was to quantify the alterations in subtalar motion following lateral column lengthening (LCL). METHODS: The subtalar motion of 14 fresh-frozen cadaveric feet was assessed using a 3-dimensional motion capture system and materials testing system (MTS). Following potting of the tibia and calcaneus, optic markers were placed into the tibia, calcaneus, and talus. The MTS was used to apply a rotational force across the subtalar joint to a torque of 5 Nm. Abduction/adduction, supination/pronation, and plantarflexion/dorsiflexion about the talus were recorded. Specimens then underwent LCL via a calcaneal neck osteotomy, which was maintained with a 12-mm porous titanium wedge. Repeat subtalar motion analysis was performed and compared to pre-LCL motion using a paired t test. RESULTS: No statistically significant differences in subtalar abduction/adduction (10.9 vs 11.8 degrees, P = .48), supination/pronation (3.5 vs 2.7 degrees, P = .31), or plantarflexion/dorsiflexion (1.6 vs 1.0 degrees, P = .10) were identified following LCL. CONCLUSION: No significant changes in subtalar motion were observed following lateral column lengthening in this biomechanical cadaveric study. CLINICAL RELEVANCE: Although these findings do not obviate concerns of clinical subtalar stiffness following lateral column lengthening for planovalgus deformity correction, they suggest that diminished postoperative subtalar motion, when it occurs, may be due to soft tissue scarring rather than alterations of joint anatomy.

Tashkandi, M.M., Alsaqer, S.F., Alhousami, T., Ali, F., Wu, Y.C., Shin, J., Mehra, P., Wolford, L.M., Gerstenfeld, L.C., Goldring, M.B. and Bais, M.V. (2020). “LOXL2 promotes aggrecan and gender-specific anabolic differences to TMJ cartilage.” Sci Rep 10(1): 20179.

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In the United States, 5-12% of adults have at least one symptom of temporomandibular joint (TMJ) disorders, including TMJ osteoarthritis (TMJ-OA). However, there is no chondroprotective agent that is approved for clinical application. We showed that LOXL2 is elevated in the regenerative response during fracture healing in mice and has a critical role in chondrogenic differentiation. Indeed, LOXL2 is an anabolic effector that attenuates pro-inflammatory signaling in OA cartilage of the TMJ and knee joint, induces chondroprotective and regenerative responses, and attenuates NF-kB signaling. The specific goal of the study was to evaluate if adenoviral delivery of LOXL2 is anabolic to human and mouse TMJ condylar cartilage in vivo and evaluate the protective and anabolic effect on cartilage-specific factors. We employed two different models to assess TMJ-OA. In one model, clinical TMJ-OA cartilage from 5 different samples in TMJ-OA cartilage plugs were implanted subcutaneously in nude mice. Adenovirus LOXL2 -treated implants showed higher mRNA levels of LOXL2, ACAN, and other anabolic genes compared to the adenovirus-Empty-treated implants. Further characterization by RNA-seq analysis showed LOXL2 promotes proteoglycan networks and extracellular matrix in human TMJ-OA cartilage implants in vivo. In order to evaluate if LOXL2-induced functional and sex-linked differences, both male and female four-month-old chondrodysplasia (Cho/+) mice, which develop progressive TMJ-OA due to a point mutation in the Col11a1 gene, were subjected to intraperitoneal injection with Adv-RFP-LOXL2 every 2 weeks for 12 weeks. The data showed that adenovirus delivery of LOXL2 upregulated LOXL2 and aggrecan (Acan), whereas MMP13 expression was slightly downregulated. The fold change expression of Acan and Runx2 induced by Adv-RFP-LOXL2 was higher in females compared to males. Interestingly, Adv-RFP-LOXL2 injection significantly increased Rankl expression in male but there was no change in females, whereas VegfB gene expression was increased in females, but not in males, as compared to those injected with Adv-RFP-Empty in respective groups. Our findings indicate that LOXL2 can induce specifically the expression of Acan and other anabolic genes in two preclinical models in vivo. Further, LOXL2 has beneficial functions in human TMJ-OA cartilage implants and promotes gender-specific anabolic responses in Cho/+ mice with progressive TMJ-OA, suggesting its merit for further study as an anabolic therapy for TMJ-OA.

Hatem, M., Nimmons, S.J., Khoury, A.N. and Martin, H.D. (2020). “Spinopelvic Parameters Do Not Predict the Sagittal Orientation of the Acetabulum.” Orthop J Sports Med 8(10): 2325967120957420.

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BACKGROUND: The orientation of the acetabulum has a fundamental role in impingement and instability of the hip, and the spinopelvic parameters are thought to predict the sagittal orientation of the acetabulum (SOA). However, similar to the acetabular version (axial orientation) and inclination (coronal orientation), the cephalic or caudal orientation of the acetabulum in the sagittal plane, or SOA, may primarily be an intrinsic feature of the acetabulum itself. PURPOSE: To determine whether the spinopelvic parameters predict the sagittal orientation of the acetabulum in individuals without lumbar deformity. STUDY DESIGN: Cross-sectional study; Level of evidence, 4. METHODS: A retrospective analysis was performed in 89 patients (94 hips; 62 female, 27 male; mean ± SD age, 45.9 ± 15.4 years) without lumbosacral deformity who underwent magnetic resonance arthrogram (MRA) for assessment of hip pain. The SOA was determined in the sagittal cut MRA. A line was drawn at the distal limit of the anterior and posterior acetabular horns longitudinally to the transverse ligament, and the angle between this line and the axial plane represented the SOA. The sacral slope, pelvic incidence, and spinopelvic tilt were determined using a 3-dimensional cursor and the axial, sagittal, and coronal cuts. All MRA studies were performed with the patient in the supine position. RESULTS: The SOA had a mean ± SD cephalic orientation of 18° ± 6.6°. No significant correlation was observed between the SOA and the sacral slope (r = -0.03; P = .77). A weak correlation was observed between the SOA and the pelvic incidence (r = 0.22; P = .03) and between the SOA and the spinopelvic tilt (r = 0.41; P < .01). CONCLUSION: The SOA cannot be presumed based on the spinopelvic parameter. Similar to the well-known parameters to assess the axial and coronal orientation of the acetabulum, the assessment of the SOA demands acetabular-specific parameters. Additional studies are necessary to assess the SOA in asymptomatic hips, including disparities between genders. Clinically significant values for abnormal SOA of the acetabulum remain to be defined.

Black, S.R., Meyers, K.N., Nguyen, J.T., Green, D.W., Brady, J.M., Maher, S.A. and Shubin Stein, B.E. (2020). “Comparison of Ligament Isometry and Patellofemoral Contact Pressures for Medial Patellofemoral Ligament Reconstruction Techniques in Skeletally Immature Patients.” Am J Sports Med Nov 2;363546520966609. [Epub ahead of print].

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BACKGROUND: Adult medial patellofemoral ligament (MPFL) reconstruction techniques are not appropriate for the skeletally immature patient given the proximity of the distal femoral physis. Biomechanical consequences of reconstructions aimed at avoiding the physis have not been adequately studied. PURPOSE: To quantify the biomechanical effects of MPFL reconstruction techniques intended for skeletally immature patients. STUDY DESIGN: Controlled laboratory study. METHODS: Four MPFL reconstruction techniques were evaluated using a computationally augmented cadaveric model: (1) Schoettle point: adult-type reconstruction; (2) epiphyseal: socket distal to the femoral physis; (3) adductor sling: graft wrapped around the adductor tendon; (4) adductor transfer: adductor tendon transferred to patella. A custom testing frame was used to cycle 8 knees for each technique from 10° to 110° of flexion. Patellofemoral kinematics were recorded using a motion camera system, contact stresses were recorded using Tekscan pressure sensors, and MPFL length was computed using an inverse kinematics computational model. Change in MPFL length, patellar facet forces, and patellar kinematics were compared using generalized estimating equation modeling. RESULTS: Schoettle point reconstruction was the most isometric, demonstrating isometry from 10° to 100°. The epiphyseal technique was isometric until 60°, after which the graft loosened with increasing flexion. The adductor sling and adductor transfer techniques were significantly more anisometric from 40° to 110°. Both grafts tightened with knee flexion and resulted in significantly more lateral patellar tilt versus the intact state in early flexion and significantly higher contact forces on the medial facet versus the epiphyseal technique in late flexion. CONCLUSION: In this cadaveric simulation, the epiphyseal technique allowed for a more isometric ligament until midflexion, when the patella engaged within the trochlear groove. The adductor sling and adductor transfer grafts became tighter in flexion, resulting in potential loss of motion, pain, graft stretching, and failure. Marginal between-condition differences in patellofemoral contact mechanics and patellar kinematics were observed in late flexion. CLINICAL RELEVANCE: In the skeletally immature patient, using an epiphyseal type MPFL reconstruction with the femoral attachment site distal to the physis results in a more isometric graft compared with techniques with attachment sites proximal to the physis.