Cervical Cord Compression and Whole-Spine Sagittal Balance: Retrospective Study Using Whole-Spine Magnetic Resonance Imaging and Cervical Cord Compression Index.

OBJECTIVE: We sought to investigate the relationship between cervical cord compression and factors related to whole-spine sagittal balance. METHODS: This retrospective single-center study included patients who visited our clinic for the evaluation of lumbar pathology including trauma and degeneration. Patients aged 60-89 years who underwent whole-spine sagittal T2 scout magnetic resonance imaging and whole-spine radiograph between 2014 and 2018 were included in our study. We consecutively enrolled 100 patients for our study without any prejudice. We collected data on patient characteristics, diagnosis, cervical cord compression index (CCI), sagittal vertical axis (C7-S1, C2-7), and other parameters related to sagittal balance such as pelvic incidence minus lumbar lordosis. Pearson correlation coefficients were calculated to compare CCI with each whole-spine sagittal balance parameter. RESULTS: Of the 100 patients, 44 were men. The mean age was 74.21 years. On the basis of Pearson correlation coefficients, CCI showed the strongest positive linear correlation with C7-S1 sagittal vertical axis (r = 0.688; P < 0.01), followed by the C2-7 sagittal vertical axis (r = 0.563; P < 0.01). CONCLUSIONS: Cervical cord compression is more likely to develop in patients with sagittal imbalance. It is important to use whole-spine radiograph and whole-spine T2 scout magnetic resonance imaging to analyze CCI in these patients.

K-line tilt as a novel radiographic parameter in cervical sagittal alignment.

OBJECTIVE: To investigate the relationship between the K-line tilt and classical cervical parameters such as the C2-C7 sagittal vertical axis (SVA), cervical lordosis, and the T1 slope in cervical sagittal alignment. We assessed whether the K-line tilt can be used as an excellent cervical parameter. METHODS: We reviewed 50 patients aged 60-89 years who visited the spine center outpatient clinic from May 2017 to September 2017 through cervical spine lateral radiography and checked the cervical spine parameters. All targeted patients were randomized without any prejudice. Radiographic measurements included the K-line tilt, C2-C7 lordosis, the C2-C7 SVA, the T1 slope, and T1 slope minus C2-C7 lordosis (T1S-CL). Pearson correlation coefficients were calculated between the K-line tilt and each cervical parameter. RESULTS: Of the 50 patients, 33 were men. The mean age of the patients was 70.84 ± 7.52 years. The mean K-line tilt was 11.28 ± 8.31°. The K-line tilt was correlated with the C2-C7 SVA (r = 0.813, P = 0.000) and T1S-CL (r = 0.315, P = 0.026). CONCLUSION: This study showed that the K-line tilt is also a useful parameter like the C2-C7 SVA and T1S-CL in cervical sagittal alignment. These slides can be retrieved under Electronic Supplementary Material.

Role of hyaluronic acid and phospholipid in the lubrication of a cobalt-chromium head for total hip arthroplasty.

The tribological performance of total hip arthroplasty has an important influence on its success rate. This study examined the concentration-dependent role of hyaluronic acid (HA) and phospholipid (dipalmitoylphosphatidylcholine, DPPC) in the boundary lubricating ability of retrieved cobalt-chromium femoral heads. The microscale frictional coefficients (µ) were measured by atomic force microscopy using a rectangular silicon cantilever integrated with sharp silicon tips. In the case of HA lubricant, the frictional coefficients decreased significantly at concentrations of 2.0 (0.16 ± 0.03) and 3.5 mg/ml (0.11 ± 0.01) while increased at 5.0 mg/ml (0.15 ± 0.01), compared to that with phosphate buffer saline (0.25 ± 0.03). The concentration-dependent lubrication behavior of DPPC was most effective when DPPC was in the physiological concentration range, showing µ = 0.16 ± 0.01 in polypropylene glycol, and 0.05 ± 0.01, 0.02 ± 0.01, and 0.03 ± 0.01 at a DPPC concentration of 0.05, 0.2, and 3.0 mg/ml, respectively. Results obtained show significant differences between the DPPC concentration groups. Conclusively, the microscale frictional response of the retrieved CoCr femoral head has a significant dependence on the concentrations of HA and DPPC. Moreover, observed optimal concentration of HA and DPPC for effective lubrication is similar to that observed in normal human synovial fluid. Therefore, a retrieval of the synovia may be considered during total hip replacement surgeries in an effort for reduction of friction between head and liner of total hip replacement implants.

Anatomic medial patellofemoral ligament reconstruction using patellar suture anchor fixation for recurrent patellar instability.

PURPOSE: The purpose of this study was to prospectively evaluate clinical and radiographic outcomes following anatomic medial patellofemoral ligament (MPFL) reconstruction using patellar suture anchor fixation for recurrent patellar instability. METHODS: Twenty patients (20 knees) were enrolled in this study. The median age was 21 years, and the median follow-up was 34.5 months. Reconstruction was performed using a hamstring autograft fixed with two suture anchors at native patellar site of the MPFL. No patient had undergone additional medial tibial tuberosity transfer. Clinical scores (Kujala, Lysholm, and Tegner score) and apprehension test were completed preoperatively and at the follow-up. Preoperative and follow-up radiographic assessments included modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle. RESULTS: The preoperative Kujala and Lysholm scores were 52.6±12.4 and 49.2±10.7, and at follow-up visits, corresponding values were 90.9±4.5 (p<0.001) and 90.9±5.2 (p<0.001). Tegner score increased from 3.0 (range 1-4) to 5.0 (range 4-7) (p<0.001). The apprehension test was positive in all patients preoperatively, but only positive in one patient at follow-up. All radiographic assessments were significantly improved; modified Insall-Salvati index (from 1.75 to 1.65) (p=0.002), congruence angle (from 6.3° to -7.0°) (p<0.001), and lateral patellofemoral angle (from 2.1° to 4.9°) (p=0.008). No patient experienced a patellar fracture or redislocation. CONCLUSION: These results are comparable to those of bone tunnel techniques reported in the literature. This study shows that anatomic MPFL reconstruction using two suture anchors is a reliable treatment option. LEVEL OF EVIDENCE: Case series with no comparison group, Level IV.

Changes in the length of the medial patellofemoral ligament: an in vivo analysis using 3-dimensional computed tomography.

BACKGROUND: The ideal points for medial patellofemoral ligament (MPFL) reconstruction have not been precisely defined. PURPOSE: To determine at which flexion angles the grafts should be fixed to best restore patellar stability as well as to compare the length change of various femoral and patellar fixation sites for current MPFL reconstruction during knee flexion in vivo. STUDY DESIGN: Descriptive laboratory study. METHODS: The right knees of 10 living patients were scanned with a high-resolution computed tomography scanner at 0°, 30°, 60°, 90°, and 120° of knee flexion, and 3-dimensional knee models were constructed using customized software. Based on recent anatomic studies and current surgical techniques, 4 femoral points (A: adductor tubercle; B: midpoint between the medial epicondyle and the adductor tubercle; C: medial epicondyle; and D: 10 mm inferior to the adductor tubercle) and 2 patellar points (30% [point 1] and 45% [point 2] from the proximal pole of the patella) were marked. The lengths of the 8 ligaments were digitally measured, and the length changes of these ligaments at the 5 different knee flexion angles were calculated. RESULTS: Two ligaments including the adductor tubercle (A1, A2) showed an increase while the knee was flexed over 60°. Four ligaments (B1, B2, D1, D2) showed a slight increase as the knee flexed from 0° to 30° and a decrease as the flexion angle exceeded 30°. Length changes in these 6 ligaments were not significantly different. There was no significant difference between 2 patellar points in the length changes of these 6 ligaments. Two ligaments including the medial epicondyle (C1, C2) showed an excessive decrease during knee flexion and showed greatest length changes. CONCLUSION: The femoral fixation sites should be located at point B or point D. Point A and point C are not ideal femoral fixation sites. The best angle for graft fixation would be near 30° of knee flexion. CLINICAL RELEVANCE: The data obtained for length and length change pattern in each virtual ligament will serve as a useful basis for improved MPFL reconstruction.

Anterior knee pain after tibial intramedullary nailing using a medial paratendinous approach.

OBJECTIVES: To determine the incidence, severity, and etiology of anterior knee pain after tibial intramedullary (IM) nailing using a medial paratendinous approach and to investigate the association between anterior knee pain and functional impairment. DESIGN: Retrospective study with current clinical and radiographic assessments. SETTING: Level I trauma center. PATIENTS: Forty-five patients with unilateral, tibial diaphyseal fractures treated with tibial IM nailing between August 2005 and January 2009. The mean follow-up was 22.3 months (range, 12-52 months). INTERVENTION: All patients underwent tibial IM nailing using a medial paratendinous approach. MAIN OUTCOME MEASUREMENTS: Anterior knee pain based on a visual analog scale and functional outcomes based on the Tegner activity score and the modified Lysholm score. RESULTS: Of the 45 patients, 16 (36%) were painless (N group), 16 (36%) had mild pain (M group), and 13 (28%) had moderate to severe pain (MS group). No group differences were found with respect to age, sex, body mass index, mode of injury, or type of fracture. With regard to nail prominence, superior nail prominence was greater in the MS group than in the other two groups (P = 0.042). There were no significant differences among the three groups in terms of anterior nail prominence (P = 0.221). The nail-apex distance in the MS group was significantly greater than in the other two groups (P = 0.033), and no significant difference was found between the N and M groups. The descending order of the activities with respect to severity of knee pain was kneeling, squatting, running, and stair ascending. Visual analog scale analysis revealed that the MS group had significantly more severe pain for all eight activities examined than the M group. At latest follow-up, the Tegner activity score was significantly lower in the MS group than in the other two groups (P = 0.008), and there were statistically significant intergroup differences in the modified Lysholm score (P < 0.001). CONCLUSION: Anterior knee pain after tibial IM nailing using a medial paratendinous approach was a frequent complication that was not uncommonly moderate to severe (28%) in Asian patients. Although the etiology of anterior knee pain is undoubtedly multifactorial, it may be related to nail prominence. Furthermore, the severity of anterior knee pain was significantly associated with functional outcome. LEVEL OF EVIDENCE: Therapeutic Level IV. See page 128 for a complete description of levels of evidence.