Severe Malalignment Research Articles

The Principles of Knee Joint Preservation: Operative Treatment Strategies.

➤ Joint alignment, meniscal status, and ligament stability are codependent factors involved in knee joint preservation, and any injury or imbalance can impact the knee articular cartilage status and can result in adverse clinical outcomes.➤ Cartilage preservation procedures in the knee will not result in optimal outcomes if there is joint malalignment, meniscal deficiency, or ligamentous instability.➤ Lower-extremity varus or valgus malalignment is a risk factor for the failure of an anterior cruciate ligament (ACL) reconstruction. It represents an indication for a high tibial osteotomy or distal femoral osteotomy in the setting of failed ACL reconstruction, and may even be considered in patients who have an initial ACL injury and severe malalignment.➤ An elevated posterior tibial slope increases the risk of failure of ACL reconstruction, whereas a decreased posterior tibial slope increases the risk of failure of posterior cruciate ligament reconstruction.

Spinopelvic sagittal compensation in adult cervical deformity.

The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity. A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2-T3 Cobb angle ≤ -30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3-S1 ≤ -60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm). Compared with asymptomatic control patients, cervical deformity was associated with increased C0-2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10-L2 Cobb angle -7.0° vs -1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0-2 lordosis (R = -0.57, p < 0.01) and lumbar lordosis (LL) (R = -0.20, p = 0.03). Cervical reconstruction resulted in decreased C0-2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0-2 lordosis (p < 0.01) and postoperative reduction of C0-2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01). Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.

KNEE PERIPROSTHETIC FRACTURES IN THE ELDERLY: CURRENT CONCEPT.

Periprosthetic fractures around total knee arthroplasty in elderly represent an emerging cause of implant revision and their incidence seems destined to further increase in the upcoming years, considering the ever-increasing number of implanted prostheses. These are complex injuries with very high complication rates. It has been estimated that the incidence of femoral periprosthetic fractures after T.K.A. ranged between 0,3 to 2,5%, but increases up to 38% when considering revision T.K.A. Patient-related risk factors for T.K.A. periprosthetic fracture (T.K.A.P.F.) include osteoporosis, age, female sex, revision arthroplasty and peri-implant osteolysis. The grate debate concerns the choice of the most appropriate fixation device for T.K.A.P.F.: closed or open reduction with internal fixation with either locked plate or intramedullary nail is the most commonly used for treating these fractures. Success of these methods depends on the fracture pattern, the stability of implants, and the patient's bone quality which is often poor in elderly, thus resulting in high complication rates. Conversely, a revision of T.K.A. (R.T.K.A.) should be considered in case of prosthetic component instability, severe comminution or metaphyseal extension of the fracture (that precludes a good fixation), previous treatments failure and severe malalignment of T.K.A. Instead megaprosthesis and allograft-prosthesis composite are necessary in case of sever bone loss. Considering the variability of the clinical scenario of T.K.A.P.F., this complex injury requires and experienced and comprehensive approach based on both facture fixation and/or revision arthroplasty.

Inter-reader consistency and exclusionary findings during radiographic screening for Phase 3 trials of tanezumab in patients with osteoarthritis

Describe the radiograph-based screening program and frequencies of ineligibility in 3 large, international, randomized, double-blind, phase 3 studies of subcutaneous tanezumab in patients with osteoarthritis (OA). Standardized bilateral shoulder, hip, and knee screening radiographs were obtained by trained imaging technologists and centrally read by 1 of 5 musculoskeletal radiology experts trained using a program-specific imaging atlas. Inter-reader consistency was tracked with test cases blindly inserted into the reader queue. Readers attended quarterly calibration meetings. Protocol-specified radiographic exclusion criteria included rapidly progressive OA (RPOA) or risk factors for RPOA (including severe malalignment of the knee, subchondral insufficiency fracture, atrophic OA, and osteonecrosis). Patients reporting disproportionate pain to radiographic evidence of OA in the hip or knee (without other pathology) were ineligible under a nonradiographic exclusion criterion. At >480 international sites, 23,079 patients entered screening and 13,797 were radiographically assessed. Across 6 sets of quarterly testing, pairwise central reader agreement on radiographic eligibility was 72-87% (kappa: 0.41-0.71) and on radiographic OA grading 77-84% (kappa: 0.68-0.75). Among the 5,773/13,797 (41.8%) patients who met exclusionary criteria, 27% had disproportionate pain to radiographic findings (~10% of knee/hip radiographs). RPOA or risk factors for RPOA were each identified in <5% of patients (usually 1 joint) and <3% of knee/hip/shoulders. The phase 3 tanezumab screening program demonstrated the utility of radiographs to screen patients entering NGF inhibitor trials. A high degree of reader concordance was achieved. RPOA and risk factors for RPOA were not commonly observed. NCT02697773, NCT02709486, NCT02528188.

All-Inside Repair of a Radial Lateral Meniscal Root Tear With an Anterior Cruciate Ligament Injury

Background: Root tears are functionally compromising injuries that require an anatomic repair for functional restoration of native joint mechanics. Posterior root tears of the lateral meniscus are commonly associated with anterior cruciate ligament (ACL) ruptures as lateral root tears contribute to anterolateral rotational instability. Two-tunnel transtibial root repair allows for root repair with superior pullout strength and can be combined with ACL reconstruction to treat this injury pattern. Indications: Two-tunnel transtibial root repair is indicated in active patients with meniscal root tears that have low-grade chondromalacia (grade II or less). It is contraindicated in patients with advanced degenerative changes (grade III-IV), severe mal-alignment, and extrusion related to advanced degenerative changes; those who cannot complete postoperative rehabilitation; and patients with significant medical comorbidities. Technique Description: After repairing a vertical horn tear of the posterior medial meniscus, a vertical tear of the posterior root of the lateral meniscus was observed. Following preparation of the anatomic footprint, 2 transtibial tunnels were drilled and sutures were passed and secured using a surgical button over the anterior tibial cortex. Horizontal repair of the tear was then performed using 2 all-inside devices. Subsequently, an ACL reconstruction was performed. Results: At 11 months postoperative, the patient has continued to progress as expected. She was able to ambulate without pain, had a symmetric and balanced gait, and was able to return to running. Discussion/Conclusion: Lateral meniscal root repairs using 2 transtibial tunnels and concomitant ACL reconstruction have yielded good and reliable clinical outcomes with low failure rates and low rates of revision surgery.

Iatrogenic ischiofemoral impingement due to high tibial osteotomy with overvalgization: a case report

BackgroundOpen wedge high tibial osteotomy is a standard procedure for frontal realignment. It is indicated in varus knee with reduced mechanical medial proximal tibia angle. Overcorrection producing a mechanical medial proximal tibia angle out of the normal range (85–90°) is not recommended because this would lead to unphysiological joint-line orientation. Osteotomies around the knee also influence the adjacent ankle and hip joints. For the hip, it is known that frontal alignment of the leg influences the ischiofemoral space. A decreased ischiofemoral space can lead to painful impingement between the ischial bone and the lesser trochanter.Case presentationA 53-year-old German woman presented with severe ischiofemoral impingement symptoms and valgus malalignment of the left leg after open wedge high tibial osteotomy, which was indicated and performed by an orthopedic surgeon with intention to treat medial knee pain due to degenerative arthritis of the medial compartment years after medial meniscectomy. The mechanical medial proximal tibia angle was 100.5°. We performed closed wedge high tibial osteotomy producing a mechanical medial proximal tibia angle of 90.0° and normal joint-line orientation. The hip pain was gone immediately after the surgery, and the patient had no signs of ischiofemoral impingement or hip pain at last follow-up 12 months after closed wedge high tibial osteotomy.ConclusionsFrontal realignment osteotomy around the knee can create problems at adjacent joints. Overvalgization of the proximal tibia made the patient compensate by hyperadduction of the hip to enable full foot sole contact with the floor. Hyperadduction of the hip decreased the ischiofemoral space, leading to severe impingement. Therefore, meticulous planning of osteotomies is important not to produce unphysiological situations or unwanted negative effects at the level of an adjacent joint.

Utility of the MISDEF2 Algorithm and Extent of Fusion in Open Adult Spinal Deformity Surgery With Minimum 2-Year Follow-up.

ObjectiveLong-segment fusion in adult spinal deformity (ASD) is often needed, but more focal surgeries may provide significant relief with less morbidity. The minimally invasive spinal deformity surgery (MISDEF2) algorithm guides minimally invasive ASD surgery, but it may be useful in open ASD surgery. We classified ASD patients undergoing focal decompression, limited decompression and fusion, and full correction according to MISDEF2 and correlated outcomes. MethodsA retrospective study of ASD patients treated by 2 surgeons at our hospital was performed. Inclusion criteria were: age > 50, minimum 2-year follow-up, and open ASD surgery. Tumor, trauma, and infections were excluded. Patients had open surgery including focal decompression, short segment fusion, or full scoliosis correction. All patients were categorized by MISDEF2 into 4 classes based upon spinopelvic parameters. Perioperative metrics were assessed. Radiographic correction, complications and reoperation were recorded. ResultsA total of 136 patients met inclusion criteria. Mean follow-up was 46±15.8 months (range, 24–118 months). Forty-seven underwent full deformity correction, 71 underwent short segment fusion, and 18 underwent decompression alone. There were 24 cases of class I, 66 cases of class II, 23 cases of class III, and 23 cases of class IV patients. Patients in class I and II had perioperative complication rates of 0% and 16.7% and revision rates of 8% and 21.2% when undergoing focal decompression or limited fusion. However, class II patients undergoing full correction had higher perioperative complications rate (p=0.03) and revision surgery rates (p=0.047). This difference was not seen in class III patients (p>0.05). All class IV patients underwent full correction, but they had higher perioperative complication rates (p<0.019), comparable revision surgery rates (p=0.27), and better radiographic realignment (p<0.001). In addition, full deformity correction was associated with longer length of stay, increased blood loss, and longer operative time (p<0.001). ConclusionThe MISDEF2 algorithm may help guide ASD surgical decision making even in open surgery, with focal treatment used in class I and II patients as a viable alternative and full correction implemented in class IV patients because of severe malalignment. However, class II patients with ASD undergoing full deformity correction do have higher complication rates.

Double-Level Osteotomy in Severe Varus Malalignment to Optimize Knee Joint Restoration

Background: Lower extremity alignment-correcting procedures for unicompartmental osteoarthritis are experiencing a rapid rise. Medial open-wedge high tibial osteotomy (MOW-HTO) thereby represents the most common technique among osteotomies but is limited in cases of severe malalignment. Some cases make a double-level osteotomy necessary. Indications: If planning of malalignment correction using a MOW-HTO results in a mechanical medial proximal tibial angle (mMPTA) of more than 93° (causing an oblique joint line), double-level osteotomy is indicated to avoid nonphysiological knee kinematics. Technique Description: After clinical examination and detailed analysis of malalignment (full-weight-bearing long-leg radiograph: hip-knee-angle [HKA], mMPTA, mechanical lateral distal femoral angle [mLDFA], joint line convergence angle [JLCA]), as well as individualized planning of the correction, the surgical procedure starts with an arthroscopy to evaluate the cartilage conditions and eventually treat intraarticular pathologies. Then, the femoral supracondylar correction is performed (closed wedge, biplanar osteotomy [ to increase bony healing]) according to the presurgical planning by resecting the osteotomy wedge with the measured length. K-wires are placed to check the correction. An angle-stable plate is used for osteosynthesis. The wedge taken out will be used as bone stock for the MOW-HTO afterward. The biplanar open-wedge tibial osteotomy is then performed subsequently using a medial tibial approach and an angle-stable plate. Opening of the osteotomy is then performed and double checked with intraoperative fluoroscopy using an alignment rod. Postoperative partial weight bearing for 6 weeks is recommended. Results: In recent literature, only few publications report on results of double-level osteotomies. Babis et al reports that it is a valuable procedure for patients with large varus deformity. Nakayama et al noted a significant improvement in patient-registered clinical outcomes in early postoperative evaluation of 20 patients. Schröter et al reports on 37 knees and findings include good clinical results, despite progressive osteoarthritis. Discussion/Conclusion: In cases of severe malalignment, adequate axis correction may require a double-level osteotomy. Exact preoperative planning is essential. Results reported in recent publications are promising. By splitting 1 large correction into 2 smaller ones, complications like hinge fracture and delayed bone healing are lowered.

The Ankle Spacer-ahemiarthroplasty for treatment of severe osteochondral defects of the talus.

The Ankle Spacer system has been developed as ajoint-preserving option for patients with failed treatment of large talar osteochondral defects (OCDs). It is aone-piece implant system that replaces the articulating upper talus surface of the tibiotalar joint. Large OCDs with failed prior surgical intervention(s) and/or multiple talar OCDs on the talar surface, posttraumatic or degenerative osteoarthritis, or avascular necrosis of the talus. Severe malalignment exceeding7° and other ankle deformities that would not allow proper rasping of the talus, obesity, blood supply limitations, severe osteopenia, and previous or active infections. The surgery is carried out via acentral approach to the ankle joint. The tibiotalar joint was distracted to remove the cartilage on the upper talar surface with special talus rasps and to perform microfracture of the entire talar surface. The appropriate Ankle Spacer trial was then inserted into the joint and fluoroscopy was used to check for proper trial size and positioning. After thorough cleaning of the prepared bone bed, the Ankle Spacer was inserted with aspecial seating instrument. One surgeon in our center implanted ten Ankle Spacers between April 2018 and October 2019. The first short-term data with follow-up of 3months were collated. No implant-related complications were recorded. American Orthopaedic Foot and Ankle Society (AOFAS) score increased from55.5 to 79.5points, European Foot and Ankle Society (EFAS) score increased from 5.6 to 13.5points, and pain score decreased from3 to 1.1points. None of the patients' radiographs showed signs of loosening or osteoarthritis progression.

Outcomes of Surgical Treatment for 138 Patients With Severe Sagittal Deformity at a Minimum 2-Year Follow-up: A Case Series.

Operative treatment of adult spinal deformity (ASD) can be very challenging with high complication rates. It is well established that patients benefit from such treatment; however, the surgical outcomes for patients with severe sagittal deformity have not been reported. To report the outcomes of patients undergoing surgical correction for severe sagittal deformity. Retrospective review of a prospective, multicenter ASD database. Inclusion criteria: operative patients age≥18, sagittal vertical axis (SVA)≥15 cm, mismatch between pelvic incidence and lumbar lordosis (PI-LL)≥30°, and/or lumbar kyphosis≥5° with minimum 2 yr follow-up. Health-related quality of life (HRQOL) scores including minimal clinically important difference (MCID)/substantial clinical benefit (SCB), sagittal and coronal radiographic values, demographic, frailty, surgical, and complication data were collected. Comparisons between 2 yr postoperative and baseline HRQOL/radiographic data were made. P<.05 was significant. A total of 138 patients were included from 502 operative patients (54.3% Female, Average (Avg) age 63.3±11.5 yr). Avg operating room (OR) time 386.2±136.5 min, estimated blood loss (EBL) 1829.8±1474.6 cc. A total of 71(51.4%) had prior fusion. A total of 89.9% were posterior fusion only. Mean posterior levels fused 11.5±4.1. A total of 44.9% had a 3-column osteotomy. All 2 yr postoperative radiographic parameters were significantly improved compared to baseline (P<.001 for all). All 2yr HRQOL measures were significantly improved compared to baseline (P<.004 for all). A total of 46.6% to 73.8% of patients met either MCID/SCB for all HRQOL. A total of 74.6% of patients had at least 1 complication, 11.6% had 4 or more complications, 33.3% had minimum 1 major complication, and 42(30.4%) had a postop revision. Patients with severe sagittal malalignment benefit from surgical correction at 2 yr postoperative both radiographically and clinically despite having a high complication rate.

Assessment of Hindfoot Alignment Comparing Weightbearing Radiography to Weightbearing Computed Tomography.

Hindfoot alignment view (HAV) radiographs are widely utilized for 2-dimensional (2D) radiographic assessment of hindfoot alignment; however, the development of weightbearing computed tomography (WBCT) may provide more accurate methods of quantifying 3-dimensional (3D) hindfoot alignment. The aim of this study was to compare the 2D calcaneal moment arm measurements on HAV radiographs with WBCT. This retrospective cohort study included 375 consecutive patients with both HAV radiographs and WBCT imaging. Measurement of the 2D hindfoot alignment moment arm was compared between both imaging modalities. The potential confounding influence of valgus/varus/neutral alignment, presence of hardware, and motion artifact were further analyzed. The intraclass correlation coefficients (ICCs) of interobserver and intraobserver reliability for measurements with both imaging modalities were excellent. Both modalities were highly correlated (Spearman coefficient, 0.930; P < .001). HAV radiographs exhibited a mean calcaneal moment arm difference of 3.9 mm in the varus direction compared with WBCT (95% CI, -4.9 to 12.8). The difference of hindfoot alignment between both modalities was comparable in subgroups with neutral/valgus/varus alignment, presence of hardware, and motion artifact. Both HAV radiographs and WBCT are highly reliable and highly correlated imaging methods for assessing hindfoot alignment. Measurements were not influenced by severe malalignment, the presence of hardware, or motion artifact on WBCT. On average, HAV radiographs overestimated 3.9 mm of varus alignment as compared with WBCT. Level III, retrospective comparative study.

An Extramedullary Spacing Block Technique to Restore Native Coronal Limb Alignment in TKA

Background: Historically, the femoral and tibial preparation for a total knee arthroplasty (TKA) are executed in isolation and then soft tissue releases are used to obtain a balanced knee. We present the clinical outcomes associated with a novel surgical method that links the tibial and femoral resections, avoids soft tissue releases, is performed extramedullary, and does not require special scans, robotics, or rapid prototype blocks. Materials and Methods: We measured hip, knee, ankle alignment radiographs preoperatively and postoperatively on 433 consecutive TKAs performed between November 2016 and August 2019. A new surgical technique called the linked and tensioned extramedullary resections (LATER technique) for both extension and flexion gap balancing was utilized without any soft tissue releases. Results: One hundred thirty-four knees were found to have severe malalignment preoperatively (≥10 degrees of varus or valgus deformities). The average angular correction was 12 degrees toward neutral alignment. Of the entire cohort, 89.2% of patients reported being completely or mostly satisfied. Patients reported “a lot of improvement” or “back to normal” (92.3%). Conclusions: The LATER technique improves coronal alignment following a complex primary TKA. Contemporary TKA can be balanced without ligament releases. The avoidance of intramedullary violation and soft tissue releases decreased intraoperative blood loss and trauma. This technique also avoids the complexities of navigation, the complications associated with fat embolism, and the manufacturing of rapid prototype blocks. The LATER technique of coronally tensioned alignment is simple to use and has excellent patient-reported satisfaction and improvement scores.

Systematic Approach to Malalignment Type Ventricular Septal Defects.

Various congenital heart diseases are associated with malalignment of a part of the ventricular septum. Most commonly, the outlet septum is malaligned toward the right or left ventricle. Less commonly, the whole or a major part of the ventricular septum is malaligned in relation to the atrial septal plane. Although the pathological conditions associated with ventricular septal malalignment have been well recognized, the descriptions are often confusing and sometimes incorrect. In this pictorial essay, we introduce our systematic approach to the assessment of malalignment type ventricular septal defects with typical case examples. The systematic approach comprises description of the essential features of malalignment, including the following: (1) the malaligned part of the ventricular septum, (2) the reference structure, (3) the mechanism of malalignment, (4) the direction of malalignment, and (5) the severity of malalignment.

The challenge of total knee arthroplasty periprosthetic fracture: a comprehensive review

Total knee arthroplasty (TKA) is a common procedure in orthopeadic surgery. It has been estimated that the incidence of periprosthetic fractures after TKA ranged between 0.3 to 2.5%, but increases to 38% when considering revision TKA.Patient-related risk factors for TKA periprosthetic fracture (TKAPF) include osteoporosis, age, female gender, revision arthroplasty and osteolysis. The choice of the most appropriate fixation device of TKAPF is a matter of debate, considering that locking plates and retrograde intramedullary are both associated with good outcomes in terms of fracture union and joint function.In case of prosthetic component instability, severe comminution or metaphyseal extension of the fracture that precludes fixation, failure of previous treatments, and severe malalignment of the TKA, revision TKA (RTKA) should be considered. Severe bone loss is another issue of concern, that might be addressed using both megaprosthesis or allograft-prosthesis composite. Considering the variability of the clinical scenario of TKAPF, a comprehensive approach based on both fracture fixation and/or revision arthroplashty is needed.

Total Knee Arthroplasty for Treatment of Osteoarthritis of the Knee with Severe Malalignment

Background: Total knee Replacement proved to be an effective surgery that leads to restoration of joint function, limb alignment, beside elimination of pain in patients with osteoarthritis.Aim of the work: To assess the results of treatment of osteoarthritis of the knee with severe malalignment by total knee arthroplasty.Patient and Methods: 30 patients (12 males & 18 females) aged from 48 - 68 years who had advanced knee arthritis were operated by total knee replacement at Al-Azhar University Hospital [Damietta] and Damietta Specialized Hospital and followed up for average 12 months from December 2016 to March 2019. All patients were assessed by history taking, examination, radiological and laboratory investigations, and all were subjected to a three-phase postoperative rehabilitation protocol. Results: 19 patients (63.3 %) had excellent final result, 8 patients (26.7%) had good result, 2 patients (6.7 %) had fair result and one patient (3.3 %) had poor final result. In addition, there was significant improvement in pain relief and joint functionConclusion: Total Knee Replacement in severe malalignment is a challenging surgery. However, it leads to significant changes in the quality of life in most patients; regarding pain relief, improvement in joint function and early return to daily activities.

Human bone marrow mesenchymal stem cell injection in subchondral lesions of knee osteoarthritis: a prospective randomized study versus contralateral arthroplasty at a mean fifteenyear follow-up.

Recently, mesenchymal stem cells (MSCs) have been proposed as potential treatment modalities for knee osteoarthritis. However, indications and long-term results have not been frequently reported. The purpose of this study was to determine whether bone marrow lesion on MRI are predictive of risk progression to total knee arthroplasty during the first ten years after subchondral cell therapy. This study included 140 adults aged 65 to 90years. These 140 patients (mean age 75.4 ± 14.2years) planned to undergo staged-bilateral total knee arthroplasty (TKA) for medial osteoarthritis, had "comparable" pain in both knees, and accepted randomization of the knees for surgery. They received TKA on one side and a subchondral injection of MSCs (from iliac bone marrow concentrate) on the contralateral knee during the same anaesthetic. The bone marrow graft of 20cm3 volume (10cc in the tibia and 10cc in the femur) contained average 7800 MSCs/mL (range 3120 to 11,560). The baseline volume of bone marrow lesions (BMLs) on the tibia and on the femoral condyle determined on MRI was average 3.4cm3 (range 0.4 to 6.4cm3). The risk of subsequent knee arthroplasty due to absence of bone marrow lesions regression as well as osteoarthritis (OA) grade was evaluated with Cox proportional-hazards ratio after control of baseline variables (number of cells injected, age, knee alignment). After treatment with MSCs injection in bone marrow lesions of the subchondral bone, medial femorotibial compartment BML volume experienced regression over 24months (mean regression 1.5cm3, range 0.8 to 3.2cm3). At the most recent follow up (average of 15years, range 10 to 20years), a total of 25 (18%) of the 140 patients underwent total knee arthroplasty performed at a mean of ten years (range, 5 to 15years) after the date of the cell therapy. The overall incidence of knee arthroplasty after cell therapy was 1.19% per person-year which was equivalent to the risk of a revision for a primary TKA in the contralateral knees of the same patient population (21 revisions, corresponding to 1.00% revision per person-year; p = 0.34). After adjusting for confounders, persistent BMLs larger than 3cm3 after cell therapy was a strong independent risk factor for total knee arthroplasty (hazard ratio HR = 4.42 [95% CI = 2.34 to 7.21]; p < 0.001), regardless of OA grade, with higher risks demonstrated for larger BMLs. Incidence rates of arthroplasty were also higher for young patients and for knees presenting severe malalignment. This study showed that subchondral bone marrow concentrate (as compared with TKA) had a sufficient effect on pain to postpone or avoid the TKA in the contra lateral joint of patients with bilateral osteoarthritis. Bone marrow lesions were predictive factors for future knee arthroplasty in the knee with subchondral cell therapy at ten years follow-up.

P33. Degenerative paraspinal muscles impact thoracic spine compensation in ASD patients

BACKGROUND CONTEXT Flattening of the thoracic spine is a common biomechanical compensatory mechanism for adult spinal deformity (ASD). The literature shows that younger ASD patients recruit more thoracic flattening than older patients. It is hypothesized that differences in muscle quality between younger and older ASD patients explains this difference in the recruitment of thoracic compensation. PURPOSE Investigate the relationship between paraspinal muscle degeneration and recruitment of thoracic compensation. STUDY DESIGN/SETTING Retrospective review of a prospective database. PATIENT SAMPLE ASD patients from a prospective database. OUTCOME MEASURES Posterior paraspinal muscle fat infiltration, thoracic kyphosis between T4 and T12 (TK) and pelvic retroversion (PT). METHODS ASD patients with spino-pelvic deformity (defined as SRS-Schwab PI-LL modifier of + or ++) and available pre-op CT imaging were identified from a retrospective database. Patients with previous fusion of the thoracic spine were excluded. Erector spinae and multifidus measurements were manually contoured on CT imagesat three vertebral levels (T2, T10, and L3), at three locations per level: immediately inferior to the superior end plate, in the middle of the vertebral body, and superior to the inferior end plate. Fat infiltration (Fat) within each muscle was defined as the number of voxels with a Hounsfield unit (HU) corresponding to fat (-190 to 0) divided by the total number of voxels. The maximum fat infiltration (MaxFat) was determined by taking the muscle with the highest percentage of Fat. After a Pearson correlation analysis, the cohort was separated into 2 groups: high Fat (HFat) and Low Fat (LFat) based on MaxFat threshold of 35%. Demographics and radiographic parameters including TK and PT were compared between groups. RESULTS Of the 57 patients (mean age 61 yrs, 75% F, BMI 28) that met inclusion, 26% had a fused lumbar spine. Assessed by +/++ SRS-Schwab modifiers, 90% of patients had severe PT malalignment and 75% a severe SVA malalignment. Breakdown of Fat and area by vertebral level was: T2 (35% and 1332mm²), T10 (30% and 1910mm²), L3 (38% and 3915mm²). TK correlated significantly with Fat at all levels from T2 to L3 (r=-0.498, r=-0.519, r=-0.472), FatMax (r=-0.470) and area at T10 (r=-0.341). PT correlated significantly with FatMax (r=0.333) and T10 Fat(r=0.548). After grouping, 31 pts were HFat, and 25 pts were LFat. HFat pts were older (64.2 vs 56.3, p=0.047) and had a greater BMI (30.1 vs 25, p=0.002). The groups did not differ in sex or rates of lumbar fusion. In terms of spinal alignment, HFat pts had a higher T1 pelvic angle (30.7° vs 23.7°), a higher TK (-34.6° vs -22.9°), and a higher PT (30.1° vs 25.2°), without difference in lumbar deformity or other sagittal parameters. CONCLUSIONS Patients with higher fat infiltration in paraspinal muscles show less compensation with the thoracic spine than patients with leaner musculature, despite having similar lumbar deformities. Consequently, patients with degenerative paraspinal musculature have more pelvic retroversion, causing greater gait disruption due to limitation in hip extension. The assessment of fatty infiltration in posterior paraspinal muscles could help identify patient compensatory profile and aid in surgical planning. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P142. Management of coronal malalignment in the setting of fractional curve correction

BACKGROUND CONTEXT Sagittal malalignment has been discussed extensively in adult spinal deformity (ASD) literature, while coronal malalignment (CM) and fractional curve (FC) have received less attention. As a result, little guidance currently exists for surgical indications in managing CM, despite it being a relatively common occurrence that can considerably impact patient wellbeing. Patients with CM significantly affected by FC are at particular risk for continued CM postoperatively, along with its complications. PURPOSE Assess types of approach to fusion of the fractional curve in ASD surgery and their relation to coronal alignment and sagittal alignment. STUDY DESIGN/SETTING Retrospective review at single institution. PATIENT SAMPLE A total of 82 ASD patients undergoing primary spinal fusion of 4 or more levels to sacrum or pelvis. OUTCOME MEASURES Baseline (BL), 1-year (Y1) postoperatively and BL-Y1 difference (ΔBL-Y1) in magnitudes of FC, coronal alignment (CA) and sagittal alignment (SA) parameters: pelvic incidence-LL (PI-LL), cervical sagittal vertical axis (cSVA), T1 pelvic angle (TPA). METHODS Patients ≥18 years old undergoing primary ≥4-level fusion to sacrum/pelvis between October 2011 and January 2018 with minimum 6-month follow-up included. Chart review performed for operative dates and details and patient follow-up information. Coronal and sagittal parameters measured using deformity measuring software program. FC measured as segmental angle between L4 and S1. CA measured as distance between C7 plumb line and central sacral vertical line. CA≥20mm designated as CM, per guidelines in literature. Chi-squared test used to compare percentages and ANOVA used to compare means, with significance set at p RESULTS A total of 82 patients studied (68.3%F, age 62.6±13.3, BMI 28.1±6.6, Charlson comorbidity index 0.80±1.16). Nine patients (10.98%) had anterior-posterior fusion (AP), 41 (50%) posterior-only fusion with interbody device (PIB), 32 (39.02%) PSF without interbody (PSF). Twenty-three patients (28.04%) had FC≥15° at BL, 7 (8.54%) at Y1. Forty-one patients (50%) had CM at BL, 35 (42.68%) at Y1. AP fusion patients had least levels fused (6.4 AP, 11.4 PIB, 11.8 PSF, p CONCLUSIONS Fusion to the sacrum/pelvis improves sagittal alignment, fractional curve and coronal alignment in most patients. However, while fractional curve and sagittal alignment are better corrected, coronal malalignment, particularly more severe malalignment at baseline, tends to persist postoperatively. Type of approach and use of interbody device does not appear to significantly impact these results. This should be considered in preoperative planning for patients with coronal deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P79. Evolution of adult spine deformity surgery practice patterns over the past decade has impacted the rates and types of complications

BACKGROUND CONTEXT Strategies for ASD surgery evolve over time based on patient populations, experience and new knowledge and techniques. Complication rates remain high for these surgeries and understanding how these practice changes may affect complication types and rates is important for ongoing efforts to improve the safety of care. PURPOSE To assess the evolution of ASD surgery practice patterns over the past decade and whether this has impacted the rates and types of complications STUDY DESIGN/SETTING Retrospective review of prospective multicenter database. PATIENT SAMPLE ASD patients from a prospective multicenter database. OUTCOME MEASURES Surgical practice patterns and complication types and rates. METHODS ASD patients treated surgically from 2008-2016 with a minimum 2-year follow-up were identified from a prospective multicenter database. Demographics, comorbidities, radiographic parameters, surgical data and complications were collected. For assessment of practice pattern and complication changes over time, 3 intervals were created: 2008-2010 (n=199), 2011-2013 (n=202), and 2014-2016 (n=197). RESULTS A total of 598 patients met inclusion (mean age 58.9 yrs, 78% women, 27.4% revision surgery). The overall cohort had high preoperative disability that significantly improved at 2-years postoperative (SRS-22: 2.8 to 3.78, p 0 for SVA (49.5% vs 63.3% vs 60.3%, p=0.034) and PI-LL (51.8% vs 67.8% vs 68.5%, p=0.001). Over time use of posterior-only approach increased (62.3% vs 78.2% vs 77.2%, p=0.003), length of fusion increased (p CONCLUSIONS In this large multicenter ASD series, ASD surgery practice patterns have significantly evolved over the past decade. Over enrollment period, patients treated surgically are older and have greater comorbidities and more severe sagittal malalignment. Use of posterior-only approaches and osteotomies has increased overtime but overall complication rates have remained stable. Change in practice in the year 2011-2013 was associated to a peak in PSO use, instrumentation failures, and severe PJK. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

194. Outcomes of surgical treatment for 138 patients with severe sagittal deformity at a minimum two-year follow-up

BACKGROUND CONTEXT The operative treatment of adult spinal deformity (ASD) can be very technically challenging with high complication rates. Despite these challenges it is well established that patients ultimately benefit from such treatment. However the surgical outcomes for patients with severe sagittal deformity have not been reported. PURPOSE To investigate whether patients with severe sagittal deformity have favorable outcomes following surgical correction. STUDY DESIGN/SETTING Retrospective review of a prospective, multicenter adult spinal deformity (ASD) database. PATIENT SAMPLE Inclusion criteria: operative patients with age ≥18, SVA ≥15cm, PI-LL ≥30°, and/or lumbar kyphosis ≥5° with minimum 2-yr follow-up. OUTCOME MEASURES Health-related quality of life (HRQOL) scores included: Oswestry Disability Index (ODI), Short Form-36 (SF36), Scoliosis Research Society (SRS22), back/leg pain numerical rating scale (NRS) and minimum clinically important difference (MCID)/substantial clinical benefit (SCB) for pts eligible to meet them. Radiographic values included: max coronal cobb angle, coronal C7 plumb line, pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), thoracic kyphosis (TK), C7 sagittal vertical axis (SVA). Demographic, frailty, surgical, and complications data were also collected. METHODS Comparisons between 2-yr postop and baseline HRQOL/radiographic data were made. P RESULTS A total of 138 pts were included (54.3% Female, ave age 63.3±11.5yrs). Ave baseline frailty score was 4.1±1.4 indicating the pt to befrail. Ave OR time 386.2±136.5min, EBL 1829.8±1474.6cc. 71 (51.4%) of the pts had a prior fusion; 89.9% posterior fusion only, 9.4% combined anterior-posterior approach. Mean number posterior levels fused 11.5±4.1. 44.9% had a 3-column osteotomy and 68.8% had interbody fusion. All 2-yr postop radiographic parameters were significantly improved compared to baseline (p 0.05). All 2-yr HRQOL measures were significantly improved compared to baseline (p CONCLUSIONS Pts with severe sagittal malalignment benefit from surgical correction at 2-yrs postop both radiographically and clinically despite having a high complication rate. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.