Florian M. Buck

Hindfoot Alignment Measurements: Rotation-Stability of Measurement Techniques on Hindfoot Alignment View and Long Axial View Radiographs

OBJECTIVE The purpose of this article is to identify the most rotation-stable hindfoot alignment measurement techniques on hindfoot alignment view and long axial view radiographs. MATERIALS AND METHODS Hindfoot alignment was quantified on hindfoot alignment view and long axial view radiographs of a phantom in different rotation positions. Rotation stability of measurements using the calcaneal axis, the medial and lateral calcaneal contour, and the apparent moment arm were graphically compared. Interreader agreement was quantified using intraclass correlation coefficient. RESULTS On hindfoot alignment view radiographs, measurements using the medial and lateral calcaneal contour were rotation stable (± 5°). Measurements using the calcaneal axis were not reliable and showed considerable divergence with phantom rotation. Measurements using the apparent moment arm manifested an almost linear relationship to phantom rotation. On long axial view radiographs, all measurements manifested an almost linear relationship to phantom rotation, whereas those using the calcaneal axis were the most rotation stable. Interreader agreement of all measurement techniques was perfect on both hindfoot alignment and long axial view radiographs (intraclass correlation coefficient, 0.8-0.98; p < 0.001). Interreader agreement was slightly better on long axial view radiographs. CONCLUSION Hindfoot alignment measurements should be performed on hindfoot alignment view radiographs using the medial or lateral calcaneal contour or on long axial view radiographs using the calcaneal axis. Interreader agreement of hindfoot alignment measurements is slightly better on long axial view radiographs than on hindfoot alignment view radiographs.

Degeneration of the Long Biceps Tendon: Comparison of MRI With Gross Anatomy and Histology

OBJECTIVE The objective of our study was to relate alterations in biceps tendon diameter and signal on MR images to gross anatomy and histology. MATERIALS AND METHODS T1-weighted, T2-weighted fat-saturated, and proton density-weighted fat-saturated spin-echo sequences were acquired in 15 cadaveric shoulders. Biceps tendon diameter (normal, flattened, thickened, and partially or completely torn) and signal intensity (compared with bone, fat, muscle, and joint fluid) were graded by two readers independently and in a blinded fashion. The distance of tendon abnormalities from the attachment at the glenoid were noted in millimeters. MRI findings were related to gross anatomic and histologic findings. RESULTS On the basis of gross anatomy, there were six normal, five flattened, two thickened, and two partially torn tendons. Reader 1 graded nine diameter changes correctly, missed two, and incorrectly graded four. The corresponding values for reader 2 were seven, one, and five, respectively, with kappa = 0.75. Histology showed mucoid degeneration (n = 13), lipoid degeneration (n = 7), and fatty infiltration (n = 6). At least one type of abnormality was found in each single tendon. Mucoid degeneration was hyperintense compared with fatty infiltration on T2-weighted fat-saturated images and hyperintense compared with magic-angle artifacts on proton density-weighted fat-saturated images. MRI-based localization of degeneration agreed well with histologic findings. CONCLUSION Diameter changes are specific but not sensitive in diagnosing tendinopathy of the biceps tendon. Increased tendon signal is most typical for mucoid degeneration but should be used with care as a sign of tendon degeneration.

Quantitative Shear-Wave US Elastography of the Supraspinatus Muscle: Reliability of the Method and Relation to Tendon Integrity and Muscle Quality

PURPOSE To evaluate the reliability of ultrasonographic (US) elastography of the supraspinatus (SSP) muscle, define normal shear-wave velocity (SWV) values, and correlate findings with tendon integrity and muscle quality. MATERIALS AND METHODS The study was approved by the local ethics committee, and written informed consent was obtained from all patients. SSP SWV (in meters per second) was prospectively assessed twice in 22 asymptomatic volunteers (mean age ± standard deviation, 53.8 years ± 15.3; 11 women and 11 men) by two independent examiners by using shear-wave elastography. Forty-four patients (mean age, 51.9 years ± 15.0; 22 women and 22 men) were prospectively included. SWV findings were compared with tendon integrity, tendon retraction (Patte classification), fatty muscle infiltration (Goutallier stages 0-IV), and muscle volume atrophy (tangent sign) on magnetic resonance (MR) images. Descriptive statistics, Spearman correlation, analysis of variance, two-sample t test, and intraclass correlation coefficient (ICC) were used. RESULTS Test-retest reliability for mean total SWV (MTSWV) was good for examiner 1 (ICC = 0.70; 95% confidence interval [CI]: 0.30, 0.87; P = .003) and excellent for examiner 2 (ICC = 0.80; 95% CI: 0.53, 0.92; P < .001). Interexaminer reliability was excellent (ICC = 0.89; 95% CI: 0.64, 0.96; P < .001). MTSWV in volunteers (3.0 m/sec ± 0.5) was significantly higher than that in patients (2.5 m/sec ± 0.5; P = .001). For tendon integrity, no significant difference in MTSWV was found. For tendon retraction, MTSWV varies significantly between patients with different degrees of retraction (P = .047). No significant differences were found for Goutallier subgroups. MTSWV was significantly lower with a positive tangent sign (P = .015; n = 10). CONCLUSION Shear-wave elastography is reproducible for assessment of the SSP muscle. Mean normal SSP SWV is 3.0 m/sec ± 0.5. SWV decreases with increasing fat content (Goutallier stage 0-III) and increases in the final stage of fatty infiltration (Goutallier stage IV).

Femoral and Tibial Torsion Measurements With 3D Models Based on Low-Dose Biplanar Radiographs in Comparison With Standard CT Measurements

OBJECTIVE The purpose of this study was to evaluate the interchangeability of femoral and tibial torsion measurements obtained with 3D models based on low-dose biplanar radiographs and standard CT measurements by testing the following two hypotheses: that there is excellent agreement between the two methods and that there is excellent interreader agreement. MATERIALS AND METHODS Two independent readers used 3D models based on low-dose simultaneous biplanar radiographs and axial CT images to measure femoral and tibial torsion in 35 patients (mean age, 65 years; range, 46-89 years) with osteoarthritis of the knee who were to undergo prosthesis insertion. The two measurements were compared by means of Bland-Altman plots and descriptive statistics. Interreader agreement was quantified with intraclass correlation coefficients. RESULTS The average differences between readers on the CT measurements were 1.3° (range, 0°-11°) for the femur and 1.5° (range, 0°-12°) for the tibia. The average differences for the measurements obtained with the 3D model were 0.1° (range, 0°-9°) for the femur and 0.8° (range, 0°-10°) for the tibia. The average differences between the two methods were 0° (range, -5° to 7°) for the femoral measurements and 3° (range, -12° to 5°) for the tibial measurements. Bland-Altman plots showed no relevant differences between the results of the two measurement modalities. Except for one measurement of femoral torsion and one measurement of tibial torsion, all results based on the 3D models were within the 95% limit of agreement (mean ± 1.96 SD). Interreader agreement was statistically significant (p < 0.001) for all measurements with high intraclass correlation coefficients (> 0.9). CONCLUSION Femoral and tibial torsion measurements obtained with 3D models based on biplanar radiographs are interchangeable with standard CT measurements in patients with osteoarthritis of the knee.

Operative treatment of chronic irreparable Achilles tendon ruptures with large flexor hallucis longus tendon transfers.

Background: Transfer of the flexor hallucis longus (FHL) tendon aims to restore function and relieve pain in chronic Achilles tendon (AT) disease. The goal of the present study was to investigate the clinical and radiographic outcomes of FHL transfer to the AT and to compare the transtendinous technique to the transosseous technique. We hypothesized that the type of technique would have a notable impact on outcome. Methods: Forty patients (42 ankles) were retrospectively reviewed and divided into group 1 (transtendinous technique, 22 patients/24 ankles) and group 2 (transosseous technique, 18 patients/18 ankles). Outcome parameters included the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score, Victorian Institute of Sports Assessment-Achilles (VISA-A) score, Foot Function Index (FFI), and Short Form-36 (SF-36) scores. Magnetic resonance imaging of the lower leg was performed preoperatively to assess muscle quality and fatty infiltration. Postoperatively, isokinetic plantar flexion strength was assessed using a Con-Trex dynamometer. Results: In group 1 (follow-up, 73 months; age, 52 years), the AOFAS score improved from 66 points to 89 points (P < .001) with average values for the VISA-A of 76 points, FFI-D pain 15%, and FFI-D function 22%. In group 2 (follow-up, 35 months; age, 56 years), the AOFAS score increased from 59 points to 85 points (P < .001) with mean values for the VISA-A 76 points, FFI-D pain 25%, and FFI-D function 24%. At follow-up, the average SF-36 score in group 1 was 66% and in group 2 was 77%. Isokinetic testing at 30 deg/s in group 1 revealed notable weakness in the operated ankle averaging 54.7 N·m (75% of normal), and in group 2 the average was 58.2 N·m (77% of normal). No statistically significant differences were found between the groups. Conclusion: The hypothesis was disproved. Both techniques for FHL transfer to AT, intratendinous and transosseous, provided good to excellent clinical and functional outcome in the treatment of irreparable AT disease. Level of Evidence: Level III, retrospective comparative series.

Femoral and tibial torsion measurement in children and adolescents: comparison of 3D models based on low-dose biplanar radiography and low-dose CT.

OBJECTIVE The purpose of this study was to evaluate the interchangeability and reliability of femoral and tibial torsion measurements in children using 3D models based on biplanar radiography compared with CT measurements. MATERIALS AND METHODS Femoral and tibial torsion were measured in 50 patients (mean age, 10.9 years; range, 4.7-14.8 years) using 3D models based on low-dose biplanar radiography by two independent readers. Measurements on transverse CT images by two independent readers served as the reference standard. Intermethod and interreader agreement was calculated using descriptive statistics, intraclass correlation coefficient (ICC), and Bland-Altman analysis. RESULTS Femoral and tibial torsion were -6°-65° and 6°-51° for 3D models based on biplanar radiography and -13°-59° and 4°-52° for CT measurements. The average difference (±SD) between the two methods was 4.9°±3.8° and 5.5°±4.1°, respectively. The intermethod ICC for biplanar radiography was 0.90 (95% CI, 0.87-0.92) for femoral torsion and 0.75 (0.68-0.80) for tibial torsion. The interreader ICC was 0.93-0.97. Mean measurement differences between the two biplanar radiography readers were 3.4° (0.0°-11.0°) for femoral torsion and 3.9° (0.0°-15.0°) for tibial torsion. Mean interreader differences at CT were 3.3° (0.0°-9.0°) for femoral and 3.0° (0.0°-10.0°) for tibial torsion. There was no trend for larger intermethod differences with decreasing age of the children. CONCLUSION Femoral and tibial torsion measurements in children using 3D models based on biplanar radiography are comparable to CT measurement results. Despite skeletal immaturity, torsion measurements in children on biplanar radiography seem to be as reliable as those on CT images.

Magnetic resonance histologic correlation in rotator cuff tendons

To relate histologic changes in rotator cuff tendons to the appearance on T1‐weighted as well as fat‐suppressed T2‐weighted and proton density‐weighted magnetic resonance imaging (MRI) sequences.

Accessory head of biceps brachii muscle: anatomy, histology, and MRI in cadavers.

OBJECTIVE The purpose of our study is to describe and define an anatomic variation located close to the bicipital groove using MRI with gross anatomic and histologic correlation in cadavers. MATERIALS AND METHODS Ten fresh male human shoulders were harvested and used in this investigation. They were derived from persons with a mean age of death of 78.9 years (age range, 58-92 years). MR arthrography using proton density-weighted sequences was used to obtain images in axial, coronal, and sagittal planes. After imaging, the specimens were cut in axial, coronal, and sagittal sections using a band saw. The slices were then photographed to allow correlation with the MR arthrographic images, followed by histologic analysis. RESULTS Two anomalous tendons, both intimate with the tendon of the long head of the biceps brachii muscle in the bicipital groove, were recognized. The origin of both tendons was in the greater tuberosity near the articular capsule. These structures had a muscular belly that was joined with the other biceps bellies. At the level of the bicipital groove, the anomalous tendons appeared as hypointense structures in proton density-weighted images, with a mostly flat morphology in axial and coronal planes. The average dimensions of these structures were 45.5 (craniocaudal)x6.2 (anteroposterior)x0.85 (mediolateral) mm. CONCLUSION The MR images, gross anatomic inspection, and histologic information led us to conclude that these anomalous structures were accessory heads of the biceps brachii muscle.

Ulnomeniscal Homologue of the Wrist: Correlation of Anatomic and MR Imaging Findings

PURPOSE To evaluate the anatomy of the ulnar side of the wrist in the region of the triangular fibrocartilage (TFC) complex, with special focus on the ulnomeniscal homologue (UMH) and its relationship to surrounding structures. MATERIALS AND METHODS Institutional review board approval and informed consent were not required. Ten upper extremities were harvested from the nonembalmed cadavers of four women and six men (age range at death, 56-97 years; mean age at death, 83 years) and used according to institutional guidelines. Magnetic resonance (MR) imaging and MR arthrography of the wrist were performed with the wrist in neutral position, maximal ulnar deviation, and maximal radial deviation by using intermediate-weighted sequences. The specimens were cut into 4-mm-thick sections that corresponded to the MR imaging planes. The gross anatomic features of the UMH and its relationship to adjacent structures were evaluated and compared with imaging findings. UMH variants, as described in previous articles on purely anatomic studies, were sought on MR images. MR findings of the wrist in neutral position were compared with those of the wrist in maximal ulnar and radial deviations. Histologic examination was used to further elucidate the structure of the UMH. RESULTS The UMH displayed complex anatomic features because of its obliquely oriented course. However, it could be divided into styloid, radioulnar, and collateral components and a distal insertion. The UMH variants described in previously published studies could be identified, but evaluation results were highly dependent on the wrist position at imaging. CONCLUSION The anatomy of the UMH is complex. For assessment of the UMH and the ulnar side of the TFC complex, coronal MR arthrography with the wrist in neutral position or radial deviation might be superior to standard MR imaging.

Comparison of T1rho Measurements in Agarose Phantoms and Human Patellar Cartilage Using 2D Multislice Spiral and 3D Magnetization Prepared Partitioned k-Space Spoiled Gradient-Echo Snapshot Techniques at 3 T

OBJECTIVE The purpose of this article is to compare in vitro T1rho measurements in agarose phantoms and articular cartilage specimens using 2D multislice spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot MRI sequences. MATERIALS AND METHODS Six phantoms (agarose concentration, 2%, 3%, and 4%; n = 2 each) and 10 axially sliced patellar specimens from five cadaveric donors were scanned at 3 T. T1rho-weighted images were acquired using 2D spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot sequences. Regions of interest were analyzed to measure T1rho values centrally within phantoms, to evaluate effects of pulse sequence and agarose concentration. In patellar specimens, regions of interest were analyzed to measure T1rho values with respect to anatomic location (the medial and lateral facets and the median ridge in deep and superficial halves of the cartilage) as well as location that exhibited magic angle effect in proton density-weighted images, to evaluate the effects of pulse sequence, anatomic location, and magic angle. RESULTS In phantoms, T1rho values were similar (p = 0.9) between sequences but decreased significantly (p < 0.001), from ∼55 to ∼29 milliseconds, as agarose concentration increased from 2% to 4%. In cartilage specimens, T1rho values were also similar between sequences (p = 0.3) but were significantly higher (p < 0.001) in the superficial layer (95-120 milliseconds) compared with the deep layer (45-75 milliseconds). CONCLUSION T1rho measurements of human patellar cartilage specimens and agarose phantoms using 2D spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot sequences gave similar values. Lower T1rho values for phantoms with higher agarose concentrations and proteoglycan concentrations that are higher in deeper layers of cartilage than in superficial layers suggest that our method is sensitive to concentration of macromolecules in biologic tissues.