Three-Dimensional Bowing Measurement of Distal Femur at Actual Size and Clinical Implications of Total Knee Arthroplasty.

Background and Objectives: To assess femoral shaft bowing (FSB) in coronal and sagittal planes and introduce the clinical implications of total knee arthroplasty (TKA) by analyzing a three-dimensional (3D) model with virtual implantation of the femoral component. Materials and Methods: Sixty-eight patients (average age: 69.1 years) underwent 3D model reconstruction of medullary canals using computed tomography (CT) data imported into Mimics® software (version 21.0). A mechanical axis (MA) line was drawn from the midportion of the femoral head to the center of the intercondylar notch. Proximal/distal straight centerlines (length, 60 mm; diameter, 1 mm) were placed in the medullary canal's center. Acute angles between these centerlines were measured to assess lateral and anterior bowing. The acute angle between the distal centerline and MA line was measured for distal coronal and sagittal alignment in both anteroposterior (AP) and lateral views. The diameter of curve (DOC) along the posterior border of the medulla was measured. Results: The mean lateral bowing in the AP view was 3.71°, and the mean anterior bowing in the lateral view was 11.82°. The average DOC of the medullary canal was 1501.68 mm. The average distal coronal alignment of all femurs was 6.40°, while the distal sagittal alignment was 2.66°. Overall, 22 femurs had coronal bowing, 42 had sagittal bowing, and 15 had both. Conclusions: In Asian populations, FSB can occur in coronal, sagittal, or both planes. Increased anterolateral FSB may lead to cortical abutment in the sagittal plane, despite limited space in the coronal plane. During TKA, distal coronal alignment guides the distal femoral valgus cut angle, whereas distal sagittal alignment aids in predicting femoral component positioning to avoid anterior notching. However, osteotomies along the anterior cortical bone intended to prevent notching may result in outliers due to differences between the distal sagittal alignment and the distal anterior cortical axis.

Biomechanical impact of elbow motion in elbow stiffness.

BACKGROUND: A mechanical block in the elbow due to osteophytes in the olecranon fossa is a common clinical symptom for elbow stiffness. PURPOSE/HYPOTHESIS: This study aims to understand the biomechanical characteristics or changes in the stiff elbow in the resting (or neutral) and swing position of the arm using a cadaveric model. The hypotheses included the following: (1) a difference exists in the articular contact pressure of the elbow by comparing the non-stiff and stiff models in in vivo studies; (2) the degree of stiffness would affect the increase of the joint loading of the elbow. STUDY DESIGN: Controlled laboratory study, cadaveric study. METHODS: Eight fresh-frozen specimens from individuals of both sexes were included in the biomechanical study. The specimen was mounted on a custom-designed jig system with gravity-assisted muscle contracture to mimic the elbow in a standing position. The elbow was tested in two conditions (the resting and passive swing). Contact pressure was recorded for three seconds in the resting position, which was the neutral position of the humerus. By dropping the forearm from 90° of the elbow flexion, the passive swing was performed. The specimens were tested sequentially in three stages of stiffness (stage 0, no stiffness; stage 1, 30° of extension limitation; and stage 2, 60° of extension limitation). After data collection was completed in stage 0, a stiff model was sequentially created for each stage. The stiff model of the elbow was created by blocking the olecranon by inserting a 2.0 K-wire into the olecranon fossa horizontally with the intercondylar axis. RESULTS: The mean contact pressures were 279 ± 23, 302 ± 6, and 349 ± 23 kPa in stages 0, 1, and 2, respectively. The increases in the mean contact pressure in stages 2 versus 0 were significant (P < 0.0001). The mean contact pressures were 297 ± 19, 310 ± 14, and 326 ± 13 kPa in stages 0, 1, and 2, respectively. The peak contact pressures were 420 ± 54, 448 ± 84, and 500 ± 67 kPa in stages 0, 1, and 2, respectively. The increases in mean contact pressure in stage 2 versus 0 were significant (P = 0.039). The increases in peak contact pressure in stages 0 versus 2 were significant (P = 0.007). CONCLUSIONS: The elbow bears the load created by gravity and muscle contracture in the resting and swing motion. Moreover, extension limitation of stiff elbow increases the load bearing in the resting position and swing motion. Careful surgical management should be considered for meticulous clearance of bony spur around olecranon fossa to resolve the extension limitation of the elbow.

Biologic plating of unstable distal radial fractures.

BACKGROUND: Volar locking plating through the flexor carpi radialis is a well-established technique for treating unstable distal radial fractures, with few reported complications. In certain circumstances, including metaphyseal comminuted fractures, bridge plating through a pronator quadratus (PQ)-sparing approach may be required to preserve the soft tissue envelope. This study describes our prospective experience with bridge plating through indirect reduction. METHODS: Thirty-three wrists (four 23A2, six 23A3, 15 23C1, and eight 23C2) underwent bridge plating through a PQ-sparing approach with indirect reduction from June 2006 to December 2010. Mean patient age was 56.8 years (range, 25-83 years), and the mean follow-up period was 47.5 months (range, 36-84 months). Changes in radiologic parameters (volar tilt, radial inclination, radial length, and ulnar variance) were analyzed, and functional results at final follow-up were evaluated by measuring the Modified Mayo Wrist Score (MMWS) and Modified Gartland-Werley Score (MGWS). RESULTS: All wrists achieved bone healing without significant complications after a single operation. At final follow-up, radial length was restored from an average of 3.7 mm to 11.0 mm, as were radial inclination, from 16.4° to 22.5°, and volar tilt, from - 9.1° to 5.5°. However, radial length was overcorrected in three wrists, and two experienced residual dorsal tilt. Excellent and good results on the MGWS were achieved in 30 wrists (90.9%). The average MMWS outcome was 92.6 (range, 75-100). CONCLUSION: Our experience with bridge plating was similar to that previously reported in the earlier publications. Compared with the conventional technique, bridge plating through a PQ-sparing approach may help in managing metaphyseal comminuted fractures of both cortices with a reduced radio-ulnar index.

Computational simulation study on ilio-sacral screw fixations for pelvic ring injuries and implications in Asian sacrum.

OBJECTIVES: Despite a high possibility of technique-related complications, ilio-sacral (IS) screw fixation is the mainstay of operative management in posterior pelvic ring injuries. We aimed to make IS screw trajectory with fully intraosseous path that was optimal and consistent, and confirm the possibility of transiliac-transsacral (TITS) screw fixation in Asian sacrum. METHODS: Eighty-two cadaveric sacra (42 males and 40 females) were enrolled and underwent continuous 1.0-mm slice computed tomography (CT) scans. CT images were imported into Mimics® software to reconstruct three-dimensional model of the pelvis. To simulate IS screws, we inserted 7.0-mm-sized TITS cylinder for first (S1) and second (S2) sacral segment and 7.0-mm oblique cylinder for S1. TITS cylinder could not be inserted into S1 of 14 models (sacral variation models) but could be inserted into the S2 of all models. The actual length of virtual IS screws was measured, and anatomic features of safe zone (SZS2) including the area, horizontal distance (HDS2), and vertical distance (VDS2) were evaluated by the possibility of TITS screw fixation in the S1. RESULTS: When the oblique cylinder was directed toward the opposite upper corner of S1 at the level of the first foramen, there was no cortical violation regardless of sacral variation. The average length of TITS cylinder was 152.3 mm (range 127.9-178.2 mm) in S1 and 136.0 mm (range 97.8-164.1 mm) in S2, and for oblique cylinder it was 99.2 mm (range 82.4-132.2 mm). The average VDS2, HDS2, and the area of SZS2 were 15.5 mm (range 8.7-24.4 mm), 18.3 mm (range 12.7-26.6 mm), and 221.1 mm2 (range 91.1-386.7 mm2), respectively. The VDS2 and SZS2 of sacral variation were significantly higher than those of normal (both p = 0.001). CONCLUSIONS: Considering the high variability of the S1, it is better to direct the IS screw trajectory toward the opposite upper corner of the S1 at the level of first sacral foramen. If a TITS screw is needed, the transverse fixation for the S2 could be performed alternatively due to its sufficient osseous site even in Asian sacrum.

Accurate application of a precontoured-locking plate for proximal humeral fractures in Asians: a cadaveric study.

OBJECTIVES: The purpose of this study was to identify the optimal position for a precontoured-locking plating (PHILOS(®)) of the proximal humerus in Asians in terms of conformity and to determine the prevalence of screw exits in the position of the highest conformity. METHODS: Twenty adult humeri and 14 cadaveric shoulders were included in this study. After placing the precontoured plate in the well-fitted position on the humerus, we measured the distance between the upper margin of the plate and the tip of greater tuberosity (GT) (distance A) and the distance between the anterior margin of the plate and lateral border of the bicipital groove (BG) (distance B). The prevalence of K-wire exits was assessed. In the 14 cadaver shoulders, the mutual relation between the most inferior locking sleeve of the optimally positioned plate and the axillary nerve was evaluated to assess the potential for axillary nerve injury. RESULTS: The precontoured plate was well-fitted and remained in a relatively constant position in all specimens. Distance A was an average of 3.6 mm (range 1.4-5.5 mm), and distance B was an average of 2.5 mm (range 0-4.6 mm). The K wire closest to the BG pierced it in four cases (20 %), and most inferior K wires exited at an average distance of 3.8 mm (range 1.6-9.0 mm) from the inferior articular margin of the humeral head. Regarding involvement of the BG, articular width was the only significant variable in the logistic regression model, with an odds' ratio of 0.610. The axillary nerve was located at an average vertical distance of 59.7 mm (range 51.8-66.9 mm) from the tip of the GT in a vertically neutral position. The results did not differ between the left and right sides (t = 0.326, p = 0.755). Although the axillary nerve was slightly inferior to the most inferior locking holes of the proximal humerus, it was located in the path of their locking sleeves on the deltoid muscle. CONCLUSION: The optimal position for the highest conformity led to ideal fixation of the proximal humerus and inferomedial support screw in Asians. However, the precontoured plate sometimes had screw exits that involved the BG, and articular width had a large impact on involvement of the BG. If locking sleeves for the most inferior holes were introduced on the deltoid muscle in a neutral position, there was high potential for injury to the axillary nerve in Koreans.

Efficacy of interscalene block combined with multimodal pain control for postoperative analgesia after rotator cuff repair.

PURPOSE: The aim of the study reported here was to compare the efficacy and safety of postoperative analgesia provided by interscalene block with multimodal pain control (IB-MPC) versus that provided by multimodal pain control (MPC) alone after arthroscopic rotator cuff repair. METHODS: Sixty consecutive patients were assigned to either the IB-MPC group (30 patients) or the MPC group (30 patients). Visual analogue scale (VAS) pain scores before surgery and through day 5 after surgery, consumption of rescue analgesic, adverse effects and complications were evaluated. RESULTS: Mean VAS pain scores immediately after surgery and on days 1 through 5 after surgery were 3.9 ± 2.6, 4.4 ± 1.5, 3.4 ± 1.3, 2.7 ± 1.3, 2.4 ± 1.2, and 2.0 ± 1.0, respectively, in the IB-MPC group and 6.2 ± 1.8, 4.1 ± 1.7, 3.2 ± 1.9, 2.7 ± 1.4, 2.5 ± 1.3, and 2.0 ± 1.2, respectively, in the MPC group. The IB-MPC group had significantly lower VAS pain score immediately after surgery than the MPC group did (P < 0.001). There were no statistically significant differences regarding consumption of rescue analgesic or adverse effects between the two groups (n.s.). In the IB-MPC group, complications related to interscalene block included tingling of the hand in three patients and numbness of the neck and ear in two. However, these symptoms resolved spontaneously within a few days. No patients had major complications related to interscalene block. CONCLUSIONS: IB-MPC achieved better pain control immediately after surgery than MPC alone, without major complications related to interscalene block. It is an effective and safe method for providing postoperative analgesia after arthroscopic rotator cuff repair. LEVEL OF EVIDENCE: Prospective Comparative Study, Prognosis Study, Level II.

Clinical outcome of autologous bone marrow aspirates concentrate (BMAC) injection in degenerative arthritis of the knee.

PURPOSE: As a treatment method of degenerative arthritis of knee, this study evaluated the clinical efficacy of the intra-articular injection of autologous bone marrow aspirates concentrate (BMAC) with adipose tissue. MATERIALS AND METHODS: Between April 2011 and May 2012, 41 patients (75 knees) who were diagnosed as a degenerative knee arthritis and underwent the BMAC injection with adipose tissue were included in this study. Mean age was 60.7 years old (ranged 53-80). Kellgren-Lawrence grade was used for assessing radiologic degree of osteoarthritis; there were each 12, 24, 33, and 6 cases of grade I, II, III, and IV. At preoperative and postoperative 3, 6, and 12 months, pain score using visual analogue scale (VAS) and functional scales were used for evaluation. RESULTS: After the procedure, mean VAS score was decreased from 7.0 preoperatively to 4.1, 3.5, and 3.3 postoperatively 3, 6, and 12 months. And functional scores were also improved; International Knee Documentation Committee score (from 37.7 preoperatively to 59.3, 66.3, 69.3 postoperatively), SF-36 health score (from 31.5 to 43.5, 45.6, 47.7), knee and osteoarthritis outcome score (from 43.1 to 64.9, 68.5, 70.6), Lysholm Knee Questionnaire (from 37.3 to 65.4, 68.6, 71.0) were all increased after the procedure. When classified according to K-L grade, the improvement of VAS score in grade IV group was 8.2 preoperatively to 5.5, 5.3, and 5.7 postoperatively, which was significantly poorer than those of grade I-III groups. In the knee functional scales, similar pattern was checked. CONCLUSIONS: BMAC injection significantly improved both knee pain and functions in the patients with degenerative arthritis of knee. Also, the injection would be more effective in early to moderate phases.

Is platelet-rich plasma able to enhance the results of arthroscopic microfracture in early osteoarthritis and cartilage lesion over 40 years of age?

Most studies suggested that arthroscopic microfracture is effective method at only less than 40 years of age. Thus, the authors thought that "how can this indication regarding age be extended?," and tried to find a way to use this technique effectively over 40 years of age. The aim of this study was the first to report the results regarding the PRP as an adjunct for arthroscopic microfracture in the early osteoarthritic (OA) knee with cartilage lesion over 40 years of age. 49 patients who underwent arthroscopic microfracture for cartilage lesion sized less than 4 cm(2) with early OA, aged 40-50 years, were enrolled and randomly divided into 2 groups: a control group with only arthroscopic microfracture (25 patients) and a study group with arthroscopic microfracture and PRP (24 patients). The patients were prospectively evaluated with VAS, IKDC score at preoperative and postoperative 1, 6, 12, and 24 months. And we perform second arthroscopies in 10 patients of each group to identify the extent of cartilage restoration at 4-6 months postoperatively. There were significant improvements in clinical results between preoperative evaluation and postoperative 2 years in both groups (p = 0.017). In the postoperative 2 years, clinical results showed significantly better in the study group than in the control group (p = 0.012). In post-arthroscopic finding, hardness and elasticity degree was better in the study group. The PRP injection with arthroscopic microfracture would be improved the results in early osteoarthritic knee with cartilage lesion in 40-50 years old, and the indication of this technique could be extended to 50 years.

The elbow is the load-bearing joint during arm swing.

BACKGROUND: Arm swing plays a role in gait by accommodating forward movement through trunk balance. This study evaluates the biomechanical characteristics of arm swing during gait. METHODS: The study performed computational musculoskeletal modeling based on motion tracking in 15 participants without musculoskeletal or gait disorder. A three-dimensional (3D) motion tracking system using three Azure Kinect (Microsoft) modules was used to obtain information in the 3D location of shoulder and elbow joints. Computational modeling using AnyBody Modeling System was performed to calculate the joint moment and range of motion (ROM) during arm swing. RESULTS: The mean ROM of the dominant elbow was 29.7°±10.2° and 14.2°±3.2° in flexion-extension and pronation-supination, respectively. The mean joint moment of the dominant elbow was 56.4±12.7 Nm, 25.6±5.2 Nm, and 19.8±4.6 Nm in flexion-extension, rotation, and abduction-adduction, respectively. CONCLUSIONS: The elbow bears the load created by gravity and muscle contracture in dynamic arm swing movement.

Structure-mechanical analysis of various fixation constructs for basicervical fractures of the proximal femur and clinical implications; finite element analysis.

OBJECTIVE: This present study was conducted to determine the structural-mechanical stability of various fixation constructs through finite element (FE) analysis following simulation of a basicervical fracture and to introduce the clinical implications. MATERIALS AND METHODS: We simulated fracture models by using a right synthetic femur (SAWBONES®). We imported the implant models into ANSYS® for placement in an optimal position. Five assembly models were constructed: (1) multiple cancellous screws (MCS), (2) FNS (femoral neck system®), (3) dynamic hip screw (DHS), (4) DHS with anti-rotation 7.0 screw (DHS + screw), and PFNA-II (Proximal Femoral Nail Antirotation-II®). The femur model's distal end was completely fixed and 7° abducted. We set the force vector at a 3° angle laterally and 15° posteriorly from the vertical ground. Analysis was done using Ansys® software with von Mises stress (VMS) in megapascals (MPa) and displacement (mm) RESULTS: The displacements of the proximal femur were 10.25 mm for MCS, 9.66 mm for DHS, 9.44 mm for DHS + screw, 9.86 mm for FNS, and 9.31 mm for PFNA-II. The maximum implant VMS was 148.94 MPa for MCS, 414.66 MPa for DHS, 385.59 MPa for DSH + screw, 464.07 MPa for FNS, and 505.07 MPa for PFNA-II. The maximum VMS at the fracture site was 621.13 MPa for MCS, 464.14 MPa for DHS, 64.51 MPa for DHS + screw, 344.54 MPa for FNS, and 647.49 MPa for PFNA-II. The maximum VMS at the fracture site was in the superior area with the high point around the posterior screw in the MCS, anterosuperior corner in the DHS, the posteroinferior site of the FNS, and posterosuperior site around the entry point in the PFNA-II. In the DHS + screw, the stresses were distributed evenly and disappeared at the maximum VMS fracture site. CONCLUSION: Based on the fracture site and implant's stress distribution, the model receiving the optimal load was a DHS + screw construct, and the FNS implant could be applied to anatomically reduced fractures without comminution. Considering the high-stress concentration around the entry point, a PFNA-II fixation has a high probability of head-neck fragment rotational instability.

Differences in Pilon Fractures According to Ipsilateral Fibular Injury Patterns: A Clinical Computed Tomography-Based Mapping Study.

Background: Preoperative verification of fracture morphology is essential for determining the definitive fixation strategy in the management of a pilon fracture. This study aimed to determine the correlation between fibular injury patterns and fracture morphologies and introduce clinical implications. Methods: Computed tomography scans of 96 pilon fractures were retrospectively analyzed and divided into three types: intact fibula, simple fracture, and multifragment fracture. The principal fracture line and comminution zones were illustrated on a plafond template and diagrammatized on a 6 × 6 grid using PowerPoint software as fracture mapping. Correlations between fibular injury patterns and fracture morphologies, including comminution zones and principal fracture lines, were analyzed. Results: The thickest comminution zone was most often located in the anterolateral quadrant. According to fibular injury patterns, the comminution zone of the multifragment group was placed two grids more lateral than that of other groups. Lateral exits of the principal fracture line in the multifragment group were much more concentrated within the fibular incisura. Conclusions: In pilon fractures, a more complex fibular fracture pattern was related to the valgus position. Moreover, the articular fracture pattern of pilon fractures differed according to coronal angulation and fibular fracture pattern. These differences should influence the operative approach and placement of the plate.

Anterolateral approach for mini-open rotator cuff repair.

PURPOSE: This study was undertaken to introduce an anterolateral approach for mini-open rotator cuff repair and evaluate its clinical outcome and effectiveness. METHODS: We evaluated 128 consecutive cases that were repaired by mini-open repair using an anterolateral approach. There were 80 men and 48 women, with an average age of 56.2 years. Average follow-up was 25.7 months. There were eight partial-thickness, 26 small, 40 medium, 39 large and 15 massive tears. After arthroscopic glenohumeral examination and subacromial decompression, we made a 3- to 4-cm skin incision from anterolateral edge of the acromion and dissected to the raphe between the anterior and middle deltoid. The torn tendon was repaired with single- or double-row technique using suture anchors. To prevent avulsion of the deltoid from the acromion, additional suturing within the bone tunnel was performed. We retrospectively evaluated clinical outcomes using the American Shoulder and Elbow Surgeon (ASES) scoring system. RESULTS: The average visual analogue scale (VAS), activity of daily living (ADL) and ASES scores improved, respectively, from 6.6, 12.0 and 36.7 preoperatively to 1.2, 26.6 and 88.2 postoperatively. There were 71 excellent, 39 good, ten fair and eight poor results. There were no statistically significant difference between final ASES scores and age, symptom duration, tear size or preoperative stiffness, but men had significantly higher final ASES scores than women (P = 0.014). CONCLUSION: Anterolateral approach for mini-open rotator cuff repair produces satisfactory results. It may also provide better visualisation for rotator cuff tears of all sizes.

Computational simulation of cephalomedullary nailing in the osteoporotic Asian femur and clinical implications.

PURPOSE: To assess the conformity of PFNA-II® and introduce clinical implications of new cephalomedullary nail (CMN) by analyzing three-dimensional (3D) modeling with virtual implantation at the actual size. MATERIALS AND METHODS: Thirty-four patients (average age; 79 years, range 68-94 years) who sustained the intertrochanteric fracture of the femur were enrolled in the present study. After importing into Mimics® software, the intact femurs on the opposite side were selected as cropping areas to reconstruct the 3D femur model with the medullary canal. PFNA-II® and new CMNs (lateral angle 0° and 2°, CCD angle 130°; CMN0° and CMN2°) were processed at the actual size and ideally placed in the proximal femur using Mimics® software. The virtual entry point (EP), nail conformity, and anatomical relationships with the adjacent structures were assessed. RESULTS: The virtual EP of PFNA-II® was placed along the cervico-trochanteric (CT) junction in the posterior half around trochanteric fossa and always medial to the tip of greater trochanter (GT). There were six abutments in PFNA-II® models, one impingement in CMN 0°, and no impingement in CMN 2°. All the models with cortical abutment showed increased anterior and lateral bowing of the proximal shaft owing to age-dependent changes. Compared with PFNA-II®, with a decreasing tendency on the mediolateral angle of new CMNs, the virtual EP shifted to the medial and anterior side towards the CT junction. By simulating the intentional positioning in the media-to-lateral direction, the abutments in the PFNA-II® model could not be avoided. Furthermore, the lag screw of CMN 0° was placed ideally at the center or inferior side of the femoral head < 10 mm in any direction without a cortical abutment. CONCLUSION: To avoid cortical abutment of CMN in the Asian geriatric femur, the virtual EP would be technically placed in the medial to the GT tip, and the implant design should be changed to decrease the mediolateral angle.

Correction to: Implications of the Overlapping Degree Between Proximal Fibula and Tibia for Placing the Optimal Syndesmotic Screw: A Virtual Cadaveric Study.

[This corrects the article DOI: 10.1007/s43465-021-00437-y.].

Implications of the Overlapping Degree Between Proximal Fibula and Tibia for Placing the Optimal Syndesmotic Screw: A Virtual Cadaveric Study.

BACKGROUND: To determine the optimal direction of the syndesmotic screw and to introduce a consistent landmark for practical application by analyzing three-dimensional (3D) modeling and virtual implantation. METHODS: A total of 105 cadaveric lower legs (50 males and 55 females; average height, 160.6 ± 7.1 cm) were used to reconstruct a 3D model by using the Mimics® software and the joint morphology was evaluated. Syndesmotic cylinders (Ø3.5 mm/Length 100 mm) were transversely placed in the proximal end of the incisura fibularis for simulating screw fixation. The tibial proximal cylinder, which was tangent to the posterior tibial condyles, was traced and the angle between the two cylinders was measured as the tibial torsion angle (TTA). After rotating the syndesmotic cylinder parallel to the ground, the overlapping degree between the proximal fibula and tibia was assessed as a radiologic indicator. RESULTS: Concerning tibial torsion, the TTA was an average of 36.7° (range, 17.2°-54.4°; SD, 8.78) When the syndesmotic cylinder was rotated to be parallel to the ground, the proximal fibula had nonlinear or linear overlap with the lateral border of the tibia, regardless of the joint morphology. In this non-overlapping view, three Weber's indices for normal fibular length could be better visualized than the mortise view. CONCLUSION: The syndesmotic cylinder in the proximal end of the incisura fibularis could be consistently placed parallel to the ground by internally rotating the tibia until there was a nonlinear or linear overlap between the proximal fibula and the tibia, regardless of the joint morphology.

Three-dimensional morphologic features of Asian atypical femur and clinical implications of cephalomedullary nail fixation: Computational measurement at actual size.

PURPOSE: (1) To analyze three-dimensional (3D) morphologic features of atypical femur fracture at actual size without projection error; and (2) to provide clinical implications of cephalomedullary nail (CMN) fixation by separating the medullary canal and the cortex. MATERIALS AND METHODS: Fifty-nine atypical femurs (opposite non-fractured femurs) were reconstructed as 3D models with medullary canal by importing CT data into Mimics® software. A reference line was drawn from the tip of the greater trochanter to the center of the intercondylar notch and used for classifying bowing grade according to the centerline of medulla. Proximal and distal straight lines (length of 60 mm, diameter of 1 mm) were placed in the centerline of medulla. Acute angles between the two straight lines were measured as lateral and anterior bowing. The acute angle by straight line and reference line was measured as proximal and distal bowing in both AP and lateral view. The diameter of curve (DOC) of medulla along the posterior border was measured. RESULTS: The anterior bowing of all femur on lateral view was an average of 13.82° (range, 6.2°-31.1°, SD 3.91), and the values of proximal and distal anterior bowing were an average of 7.82° (range, 2.7°-14.3°, SD 2.23) and 6.0° (range, 2.2°-16.8°, SD 2.31), respectively. The lateral bowing of all femur on AP view was an average of 5.49° (range, 0.1°-17.3°, SD 4.48), and the values of proximal and distal anterior bowing were an average of 3.64° (range, 0.1°-11.3°, SD 2.70) and 2.48° (range, 0-7.4°, SD 1.98), respectively. The medullary canal was changed to be straightened and more bowed anteriorly. Concerning the lateral bowing grade of entire diaphysis, it was grade -I for 15 femurs, grade 0 for 21 femurs, grade I for nine femurs, grade II for five femurs, and grade III for nine femurs. Regarding anterior bowing grade, it was grade II for 14 femurs and grade III for 45 femurs. The average diameter of medullary canal was 1276.3 ± 232.25 mm. CONCLUSION: Asian atypical femur had three morphologic features: (1) straightened medullary canal, (2) positive values of lateral bowing, and (3) significantly increased ante-curvature of medullary canal. Considering that conventional CMN had about 4° of mediolateral angle, the disparity between implant and medullary canal might be clear. Thus, new nail design for Asian atypical femur that could increase the radius of curve (ROC) but decrease the mediolateral angle needs to be introduced.

Biomechanical Effect of Disc Height on the Components of the Lumbar Column at the Same Axial Load: A Finite-Element Study.

Intervertebral discs are fibrocartilage structures, which play a role in buffering the compression applied to the vertebral bodies evenly while permitting limited movements. According to several previous studies, degenerative changes in the intervertebral disc could be accelerated by factors, such as aging, the female sex, obesity, and smoking. As degenerative change progresses, the disc height could be reduced due to the dehydration of the nucleus pulposus. This study aimed to quantitatively analyze the pressure that each structure of the spine receives according to the change in the disc height and predict the physiological effect of disc height on the spine. We analyzed the biomechanical effect on spinal structures when the disc height was decreased using a finite-element method investigation of the lumbar spine. Using a 3D FE model, the degree and distribution of von-Mises stress according to the disc height change were measured by applying the load of four different motions to the lumbar spine. The height was changed by dividing the anterior and posterior parts of the disc, and analysis was performed in the following four motions: flexion, extension, lateral bending, and axial rotation. Except for a few circumstances, the stress applied to the structure generally increased as the disc height decreased. Such a phenomenon was more pronounced when the direction in which the force was concentrated coincided with the portion where the disc height decreased. This study demonstrated that the degree of stress applied to the spinal structure generally increases as the disc height decreases. The increase in stress was more prominent when the part where the disc height was decreased and the part where the moment was additionally applied coincided. Disc height reduction could accelerate degenerative changes in the spine. Therefore, eliminating the controllable risk factors that cause disc height reduction may be beneficial for spinal health.

Analysis of the physiological load on lumbar vertebrae in patients with osteoporosis: a finite-element study.

This study aims to investigate the difference in physiological loading on the spine in three different motions (flexion-extension, lateral bending, and axial rotation) between osteoporotic and normal spines, using finite element modelling. A three-dimensional finite element (FE) model centered on the lumbar spine was constructed. We applied two different material properties of osteoporotic and normal spines. For the FE analysis, three loading conditions (flexion-extension, lateral bending, and axial rotation) were applied. The von Mises stress was higher on the nucleus pulposus at all vertebral levels in all movements, in the osteoporosis group than in the normal group. On the annulus fibrosus, the von Mises stress increased at the level of L3-L4, L4-L5, and L5-S in the flexion-extension group and at L4-L5 and L5-S levels in the lateral bending group. The values of two motions, flexion-extension and lateral bending, increased in the L4 and L5 cortical bones. In axial rotation, the von Mises stress increased at the level of L5 of cortical bone. Additionally, the von Mises stress increased in the lower endplate of L5-S and L4-L5 in all movements, especially lateral bending. Even in the group with no increase, there was a part that received increased von Mises stress locally for each element in the three-dimensional reconstructed view of the pressure distribution in color. The von Mises stress on the lumbar region in the three loading conditions, was greater in most components of osteoporotic vertebrae than in normal vertebrae and the value was highest in the nucleus pulposus. Considering the increase in the measured von Mises stress and the local increase in the pressure distribution, we believe that these results can contribute to explaining discogenic pain and degeneration.

Effects of Location and Volume of Intraosseous Cement on Adjacent Level of Osteoporotic Spine Undergoing Kyphoplasty: Finite Element Analysis.

OBJECTIVE: Kyphoplasty (KP) is a surgery used to reduce pain and increase stability by injecting medical bone cement into broken vertebrae. The purpose of this study was to determine the ideal amount of cement and injection site by analyzing forces with the finite element method. METHODS: We modeled the anatomical structure of the vertebra and injected the cement at T12. By increasing the amount of cement from 1 cc to 22 cc, stress applied to T11 and L1 cortical was calculated. In addition, stress applied to the adjacent KP level was calculated with different injection sites (medial, anterosuperior, posterosuperior, anteroinferior, and posteroinferior). After 5 cc cement was inserted, adjacent end plate stress was analyzed. RESULTS: In this study, break point adjacent bone stress according to the capacity of cement was bimodal. Flexion/extension and lateral bending conditions showed similar break points (11.5-11.7 cc and 18.5-18.6 cc, respectively). When cement injection was changed, front under and back under had the highest stress values among various parts, whereas the center position showed the lowest stress value. CONCLUSIONS: With increasing amount of bone cement, stress on the upper and lower end plates of the cemented segment increased significantly. Thus, increasing cement amount to be more than 11.5 cc has a potential risk of adjacent fracture. Centrally injected bone cement can lower the risk of adjacent fracture after percutaneous KP.

Percutaneous bridge plating of extra-articular distal fibular fracture for the management of distal tibia type III open fracture.

PURPOSE: The aim of this study is to conduct clinical and radiographic evaluations of the use of percutaneous bridge plating for distal fibular fractures combined with distal tibia type III open fractures. METHODS: Thirty-four patients with acute distal third fibular shaft fractures (4F2A(c) and 4F2B(c) according to the AO/OTA classification) combined with distal tibia type III open fractures were enrolled. Concurrent fibular fractures were fixed with the percutaneous bridge plating simultaneously, while distal tibia open fractures were temporally stabilized with a spanning external fixator. Clinical and radiographic outcomes were evaluated using the Lower Extremity Functional Scale (LEFS), the proportional length difference of the fibula, the talocrural angle, the union rate of the fibula and tibia, the operation time, and complications at the final follow-up. RESULTS: All fibular fractures healed with an average bone healing time of 20.7 ± 6.3 weeks (range, 16-35). The mean proportional length difference was 0.492 ± 0.732% compared with that in the uninjured fibula. The functional assessment result according to the LEFS was 74.0 ± 3.70 points (range, 57-80). No cases of fibula fracture infection developed throughout the follow-up period in any of the patients. Iatrogenic postoperative superficial peroneal nerve injury was not found in any of the patients. CONCLUSION: With the perspective of minimizing soft tissue problems due to high-energy trauma, the application of percutaneous bridge plating for the treatment of distal fibular fractures can be an alternative to conventional treatment methods.