Range Of Motion Stability Research Articles

SIMPLE ELBOW DISLOCATIONS – FROM DIAGNOSIS TO TREATMENT

Introduction Elbow dislocation is a common injury that one may encounter in an emergency setting. Every dislocation can be categorized as simple or complex depending on bony involvement, and treatment depends mainly on injury pattern as well as on post-reduction stability. Aim The aim of this review is to present the current state of the art concerning diagnosis and treatment of simple elbow dislocations and to propose an algorithm based on which one might successfully provide patients with adequate care. Material and methods Twelve papers dating back from 1999 to 2020 using PubMed, Cochrane Library were reviewed to search for evidence-based treatment methods associated with best results after acute elbow dislocation. Results Quick mobilization in a stable range of motion after joint reduction reduces the risk of long term complications and pain greatly. Careful examination of the joint involved is crucial in terms of correct therapy selection. In a minority of cases with persisting instability, operative treatment is the treatment of choice. Conclusions In most cases involving simple elbow dislocations, appropriate conservative treatment brings favorable results and elbow stiffness or range of motion (ROM) restriction are rare. However, in rare cases, operative repair is mandatory.

The impact of hip-spine relations on the results of total hip arthroplasty (literature review)

Spine balance can alter THA outcomes, but the exact mechanism is not yet well recognized. We aimed at bridging the gap between hip and spine surgeons with an up-to-date analysis of the best available literature review concerning to data as for total hip arthroplasty results of those patient with concomitant spine disorders. In total hip arthroplasty accurate acetabular cup placement is essential for impingement free and stable range of motion. For decades, hip surgeons have relied on traditional safe acetabular zones to reduce prosthetic instability. Nevertheless, hip dislocation is one of the most common complications following total hip arthroplasty. Numerous studies have shown that patients with abnormal spinopelvic mobility due to degene­rative spinal diseases and after spinal fusion surgery had an increased rate of dislocations after THA. In our review we described the main spine-pelvic parameters, such as pelvic tilt, sacral slope, pelvic incidence, lumbar lordosis etc. and spino-pelvic motions and how they can change in standing and sitting postures. Measurements of these parameters are necessary for presurgical planning before hip arthroplasty especially those patients who had previously made spine fusion. A review of lite­rature shows that sagittal pelvic kinematics, but not the pelvic incidence, influences the risk of prosthetic impingement or dislocation. Pelvic position is dynamic during gait and other daily living activities. Variations in anteroposterior pelvic tilt affects the resulting spatial orientation of the acetabulum. Recommendations for cup positioning are switching from a classic Lewinneck safe zone to a patient-specific approach, with the standing cup orientation giving way to a new parameter of interest: the functional orientation of the cup. Thus, functional cup anterversion should be taken into consideration. Abnormal spinopelvic mobility is a risk factor for THA dislocation. Thus patients with combined spine and hip pathology are at higher risk for further complications and they should be identified and screened more carefully. Key words. Spine-pelvic relations, sagittal alingement, hip arthroplasty, dislocation

Biomechanics of open versus minimally invasive deformity correction:​ comparison of stability and rod strain between pedicle subtraction osteotomy and anterior column realignment.

Anterior column realignment (ACR) is a new minimally invasive approach for deformity correction that achieves a degree of lordosis similar to that obtained with pedicle subtraction osteotomy (PSO). This study compared the biomechanical profiles of ACR with PSO using range of motion (ROM) and posterior rod strain (RS) to gain insight into the ACR technique and the necessary surgical strategies to optimize longevity and stability. An in vitro biomechanical study using standard flexibility testing (7.5 Nm) was performed on 14 human cadaveric specimens, separated into 2 groups similar in age, sex, bone mineral density, and intact ROM. For group 1 (n = 7, instrumented L1-S1), a 30° ACR was performed at L3-4. For group 2 (n = 7, instrumented T12-S1), a 30° L3 PSO was performed. Specimens were subjected to nondestructive loads in flexion, extension, axial rotation, lateral bending, and compression. Conditions tested were 1) intact, 2) pedicle screw with 2 rods (PSR), 3) ACR or PSO with 2 rods (+2R), and 4) ACR or PSO with 4 rods (+4R). Primary outcome measures of interest were ROM stability and posterior RS at L3-4. No difference was observed between groups in lumbar lordosis (p = 0.83) or focal angular lordosis at L3-4 (p = 0.75). No differences in stability were observed between ACR+2R and PSO+2R (p ≥ 0.06);​ however, ACR+2R was significantly less stable than PSR in flexion and extension (p ≤ 0.02), whereas PSO+2R was less stable than PSR only in extension (p = 0.04). ACR+4R was more stable than ACR+2R in flexion, extension, left axial rotation, and compression (p ≤ 0.02). PSO+4R was more stable than PSO+2R only in extension (p = 0.04). Both ACR+2R and PSO+2R resulted in significant increases in RS in flexion and extension compared with PSR (p ≤ 0.032). RS in flexion and extension decreased significantly for ACR+4R versus ACR+2R and for PSO+4R versus PSO+2R (p ≤ 0.047). PSO+2R yielded lower RS than ACR+2R in compression (p = 0.03). No differences existed in RS between ACR+4R and PSO+4R (p ≥ 0.05). Although ACR appeared to be slightly more destabilizing than PSO using traditional 2R fixation, both techniques resulted in significant increases in posterior RS. The 4R technique increased stability in ACR and decreased RS in both ACR and PSO but may be more beneficial in ACR. Longer-term clinical studies are needed to appropriately identify the durability of the ACR technique in deformity correction.

Optimizing biomechanics of anterior column realignment for minimally invasive deformity correction

BACKGROUND CONTEXTAnterior column realignment (ACR) is a powerful but destabilizing minimally invasive technique for sagittal deformity correction. Optimal biomechanical design of the ACR construct is unknown. PURPOSEEvaluate the effect of ACR design on radiographic lordosis, range of motion (ROM) stability, and rod strain (RS) in a cadaveric model. STUDY DESIGN/SETTINGCadaveric biomechanical study. PATIENT SAMPLESeven fresh-frozen lumbar spine cadaveric specimens (T12–sacrum) underwent ACR at L3–L4 with a 30° implant. OUTCOME MEASURESPrimary outcome measure of interest was maximum segmental lordosis measured using lateral radiograph. Secondary outcomes were ROM stability and posterior RS at L3/4. METHODSEffect of grade 1 and grade 2 osteotomies with single-screw anterolateral fixation (1XLP) or 2-screw anterolateral fixation (2XLP) on lordosis was determined radiographically. Nondestructive flexibility tests were used to assess ROM and RS at L3–L4 in flexion, extension, lateral bending, and axial rotation. Conditions included (1) intact, (2) pedicle screw fixation and 2 rods (2R), (3) ACR+1XLP with 2R, (4) ACR+2XLP+2R, (5) ACR+1XLP with 4 rods (4R) (+4R), and (6) ACR+2XLP+4R. RESULTSSegmental lordosis was similar between ACR+1XLP and ACR+2XLP (p>.28). ACR+1XLP+2R was significantly less stable than all other conditions in flexion, extension, and axial rotation (p<.014); however, adding an extra screw improved stability to levels equal to 4R conditions (p>.36). Adding 4R to ACR+1XLP reduced RS in all directions of loading (p<.048), whereas adding a second screw did not (p>.12). There was no difference in strain between ACR+1XLP+4R and ACR+2XLP+4R (p>.55). CONCLUSIONSFor maximum stability, ACR constructs should contain either fixation into both vertebral bodies (2XLP) or accessory rods (4R). 2XLP can be used without compromising the maximal achievable lordosis but does not provide the same RS reduction as 4R. CLINICAL SIGNIFICANCEACR is a highly destabilizing technique that is increasingly being used for minimally invasive deformity correction. These biomechanical data will help clinicians optimize ACR construct design.

138. Can dual-headed pedicle screws simplify use of dual rods and without sacrificing biomechanical stability?

BACKGROUND CONTEXT Long-segment fixation exposes instrumentation to substantial stresses and rod strain (RS), which result in high fracture rates. Supplemental rods provide greater stability, reduced posterior rod strain, and decreased fracture rates. Use of supplemental rods leads to reduced RS and decreased fracture risk; however the ideal method of supplemental rod attachment is unknown. Traditional methods of attachment include side connectors, which complicate intraoperative technique, and may increase duration of surgery and intraoperative contouring. Novel dual-tulip-headed screws have been developed to facilitate supplemental rod fixation for long segment constructs. PURPOSE The goal of this study was to evaluate a novel connector design and compare with traditional side-connectors such as a fixed angle connector (FAC) or variable angle connector (VAC). We hypothesized that dual-tulip-headed (DTH) screws would provide similar reduction in rod strain compared to fixed (FAC) or variable angled connectors (VAC). STUDY DESIGN/SETTING In vitro biomechanical study using human cadaveric specimens. PATIENT SAMPLE Seven fresh-frozen lumbar spine cadaveric specimens (L1–Ilium) were selected for this study (3F/4M, 48±7yrs, DEXA 0.9±0.1g/cm2). OUTCOME MEASURES Primary outcome measures of interest were range of motion (ROM) stability, posterior rod strain (RS) at L5/S1, and sacral screw bending moments (SM). METHODS Standard nondestructive flexibility tests (7.5 Nm) and compression tests (400 N) were performed (L1-ilium) to compare range of motion stability (ROM), posterior rod strain at L5-S1 (RS), and S1 screw bending moment (SM) between several supplemental 4-rod constructs (4R) vs standard 2-rod construction (2R). Directions of motion included: flexion (FL), extension (EX), left and right lateral bending (LLB, RLB), left and right axial rotation (LAR, RAR), and compression (C). Transforaminal lumbar interbody fusion (TLIF) was performed at L5/S1. Conditions included: (1) 2R, (2) dual tulip head with 4R (DTH), (3) fixed-angle connector with 4R (FAC), and (4) variable-angle connectors with 4R (VAC). Data were analyzed using RM-ANOVA. RESULTS Overall, there were no significant differences in ROM across the lumbosacral junction between conditions (p >.068). Compared to 2R, DTH and FAC significantly reduced RS in extension, LAR, and compression (p ≤.031). VAC significantly decreased RS compared to 2R in flexion, extension, LAR, RAR and compression (p ≤.033), and significantly decreased RS compared to DTH in extension (p=.024). DTH resulted in mildly increased SM compared to 2R in LAR and RAR (p ≤.003), and in LLB, RLB, LAR, RAR compared to FAC and VAC (p ≤.016). FAC and FAC resulted in decreased SM compared to 2R in RLB and LLB (p ≤.025). CONCLUSIONS Strain across the lumbosacral junction is high. Supplemental rod fixation with DTH is an effective strategy for reducing RS across the lumbosacral junction. However, the greatest reduction in RS and SM was achieved with variable connectors, likely due to their ability to allow for differential rod bending. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.

246. Comparison of biomechanical stability and rod strain between anterior column alignment and pedicle subtraction osteotomy

BACKGROUND CONTEXT Traditionally, open approaches have been used for deformity correction surgeries; chief among these includes the pedicle subtraction osteotomy (PSO), which provides significant sagittal correction. While minimally invasive approaches offer a potentially lower complication profile, little is known about their stability and performance compared to open techniques. Anterior column realignment (ACR) is a new minimally invasive approach for deformity correction with similar degree of lordosis to pedicle subtraction osteotomy (PSO). No prior studies have compared the stability of ACR and PSO constructs. PURPOSE Understanding the biomechanical difference between ACR and PSO may equip the surgeons to maximize the outcomes, increase implant longevity, lower their complication rates and avoid implant failure. The goal of this study was to compare the biomechanical profiles ACR compared to PSO in terms of range of motion stability (ROM) and posterior rod strain (RS) to gain greater insight into the ACR technique and necessary surgical strategies to optimize longevity and stability. We hypothesized ACR will provide greater stability than PSO and yield lower degree of posterior rod strain. STUDY DESIGN/SETTING In vitro biomechanical study using human cadaveric specimens. PATIENT SAMPLE A total of 14 fresh-frozen lumbar spine cadaveric specimens (T11–sacrum) were selected for this study. OUTCOME MEASURES Primary outcome measures of interest were range of motion (ROM) stability and posterior rod strain (RS) at L3/4. METHODS Standard flexibility testing (7.5 Nm) was performed on 14 human cadaveric specimens, separated into two groups by L1-S1 intact ROM. For Group 1, a 30° hyperlordotic ACR was performed at L3/4; for Group 2, a 30° L3 PSO was performed. Flexion(FL), extension(EX), axial rotation (AR), lateral bending (LB), and compression(C). Conditions tested: (1) intact, (2) Pedicle Screw/ 2 rod (PSR) (3) ACR or PSO+2 rods (2R), 4) ACR or PSO+4R. Data were normalized, and analyzed using RM-ANOVA or ANOVA (p RESULTS No difference was observed between PSO and ACR in lumbar lordosis (p=.83) or focal bend (p=.75). While there were no differences in stability between ACR+2R and PSO+2R (p>.065), ACR appeared to be significantly destabilized compared to PSR in FL and EX (p CONCLUSIONS While ACR appears to be more destabilizing than PSO in a biomechanical model, both techniques result in significant increases in posterior rod strain. The 4R technique increases stability for ACR and decreases RS in both in ACR and PSO, but may be more effective in ACR. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Polyethylene Hip Resurfacing to Treat Arthritis and Severe Acetabular Insufficiency

BackgroundHip dysplasia is the leading cause of hip arthritis in young adults. These patients often participate in active lifestyles that require a full and stable range of motion. MethodsBetween 2001 and 2011, 232 consecutive polyethylene resurfacing arthroplasties were performed in 201 patients with advanced arthritis from severe acetabular insufficiency due to dysplasia. All patients had Crowe II or III disease. Their mean age at surgery was 43 years. A 2-piece cementless acetabular resurfacing shell with dome screws and a highly cross-linked polyethylene liner were implanted to provide secure fixation, early weight bearing, and a stable hip. Additional structural bone grafts and/or fixation were not used. A cemented or cementless resurfacing prosthesis was used on the femur. ResultsDuring a mean follow-up of 10 years, 8 hips (3.5%) were converted to a total hip arthroplasty due to acetabular loosening (1), femoral neck fracture (2), femoral osteonecrosis (2), infection (2), or persistent pain (1), resulting in a mean survival of the resurfacing prostheses of 96% (95% confidence interval 89-98). There were no pending revisions and no dislocations. At 2 years postoperative, Harris Hip Scores improved from a preoperative mean of 55 to 97 and University of California Los Angeles activity scores improved from 5 to 8. ConclusionHip resurfacing using a 2-piece polyethylene acetabular component for advanced dysplasia has resulted in excellent function and implant survivorship with a low rate of complications at mid-term follow-up.

Selected anteromedial coronoid fractures can be treated nonoperatively

Surgical fixation is currently recommended for unstable anteromedial coronoid fractures, but the role of nonoperative management is not well defined. Our purpose was to report the functional and radiographic outcomes of select patients managed nonoperatively. Between 2006 and 2012, 10 patients with anteromedial coronoid fractures underwent nonoperative treatment. Outcomes assessed included elbow range of motion (ROM), stability, strength, radiographs, and 3 functional questionnaires, including the Patient-Rated Elbow Evaluation, Disabilities of Arm, Shoulder and Hand, and Mayo Elbow Performance Index. There were 9 anteromedial subtype 2 coronoid fractures and 1 subtype 3. Mean fragment size was 5 mm, with a mean displacement of 3 mm for the subtype 2 fractures. The subtype 3 fracture was 9 mm in size with 1 mm of maximal gap displacement. At a mean follow-up of 50 months (range, 12-83 months), the average ROM of the affected elbow was 137° ± 8° of flexion, 2° ± 5° of extension, 88° ± 5° of pronation, and 86° ± 10° of supination. The mean Patient-Rated Elbow Evaluation score was 9 ± 13, Mayo Elbow Performance Index score was 94 ± 8, and the Disabilities of Arm, Shoulder and Hand score was 7 ± 9. All patients had bony union without radiographic arthrosis. There were no cases of recurrent instability or delayed surgical intervention. Current indications for nonoperative management, based on the results of this study, include fractures that are small, minimally displaced, and most importantly, demonstrate no evidence of elbow subluxation. The elbow joint must be congruent and demonstrate a stable ROM to a minimum of 30° of extension. For selected anteromedial coronoid fractures, nonoperative management is an option that can lead to good clinical and radiographic outcomes.

Stability of Serial Range-of-Motion Measurements of the Lower Extremities in Children With Cerebral Palsy: Can We Do Better?

Serial joint range-of-motion (ROM) measurements are an important component of assessments for children with cerebral palsy. Most research has studied ROM stability using group data. Examination of longitudinal intraindividual measures may provide more clinically relevant information about measurement variability. The aim of this study was to examine the stability of intraindividual longitudinal measurements of hip abduction (ABD), popliteal angle (POP), and ankle dorsiflexion (ADF) ROM measures of children with cerebral palsy. Secondary data analyses were performed. The stability patterns of individual serial measurements of ABD, POP, and ADF from 85 children (mean age=3.8 years, SD=1.4) collected at baseline (T1), 3 months (T2), 6 months (T3), and 9 months (T4) were examined using T1 as the anchor and bandwidths of ±15 degrees (ABD and POP) and ±10 degrees (ADF) as acceptable variability. Frequencies of stability categories (0°-5°, 5.1°-10°, 10.1°-15°, and >15°) were calculated. Patterns of stability across the 4 time periods also were examined. Group means (T1-T4) were compared using repeated-measures analysis of variance. No significant differences in group means were found except for ABD. Stability patterns revealed that 43.3% to 69.5% of joint measurements were stable with T1 measurements across all 3 subsequent measurements. Stability category frequencies showed that many measurements (ABD=17%, POP=29.9%, and ADF=37.1%) went outside the variability bandwidths even though 39% or more of joint measurements had a change of 5 degrees or less over time. Measurement error and true measurement variability cannot be disentangled. The results cannot be extrapolated to other joint ROMs. Individual ROM serial measurement exhibits more variability than group data. Range-of-motion data must be interpreted with caution clinically and efforts made to ensure standardization of data collection methods.

Compliant positioning of total hip components for optimal range of motion

Impingement between femoral neck and endoprosthetic cup is one of the causes for dislocation in total hip arthroplasty (THA). Choosing a correct combined orientation of both components, the acetabular cup and femoral stem, in manual or computer-assisted implantation will yield a maximized, stable range of motion (ROM) and will reduce the risk for dislocation. A mathematical model of a THA was developed to determine the optimal combination of cup inclination, cup anteversion, and stem antetorsion for maximizing ROM and minimizing the risk for cup–neck impingement. Single and combined hip joint motions were tested. A radiographic definition was used for component orientation. Additional parameters, such as stem–neck (CCD) angle, head–neck ratio, and the design of the acetabular opening, were also considered. The model showed that a maximized and safe ROM requires compliant, well-defined combinations of cup inclination, cup anteversion, and stem antetorsion depending on the intended ROM. Radiographic cup anteversion and stem antetorsion were linearly correlated. Additional internal rotation reduced flexion, and additional external rotation reduced extension, abduction and adduction. The articulating hemispheric surface of acetabular cups should be oriented between 40° and 45° of radiographic inclination, between 20° and 28° of radiographic cup anteversion, and should be combined with stem antetorsion so that the sum of cup anteversion plus 0.7 times the stem antetorsion equals 37°. Final component orientation must also consider cup containment, implant impingement with bone and soft tissue, and preoperative skeletal contractures or deformities to achieve the optimal compromise for each patient.

Lateral Rotatory Dislocation of the Ankle Without Fracture

A 34-year-old woman sustained a closed lateral rotatory dislocation of the ankle without a fracture. Treatment was by closed reduction and cast immobilization for 6 weeks. After removal of the cast, her ankle was stable. Stress radiographs of both the affected and contralateral ankles were normal. One year after injury the patient demonstrated a full, pain-free, stable range of motion. The patient exhibited generalized ligamentous laxity, which may have contributed to her tendency to dislocate the talus within the mortise.