Radiographic determinants of the elbow rotation axis: experimental identification and quantitative validation.

This study identifies new radiographic indices to approximate the location of the elbow rotational axis. With use of electromagnetic motion tracking source data, the average rotational axis of the ulnohumeral articulation was calculated in seven cadaveric specimens. Quasi-lateral radiographs of the elbow specimens were then analyzed to identify radiographic landmarks of the elbow axis in the lateral view. The spatial relationships of these landmarks with the elbow aligned on-axis were contrasted with their relationships in eight distinct off-axis alignments. Elbow axis orientation in the transverse plane (internal/external rotation) was identified by the location of a dense intramedullary cortical line, appearing in the projection of the distal humerus in relation to the periosteal surface of the posterior cortex of the humerus. This intramedullary line corresponds to the posteromedial cortex of the distal humerus. Correct alignment occurred when this line laid 27.1+/-3.7% of the anteroposterior humeral diameter anterior from the periosteal surface of the posterior cortex. Axis orientation in the coronal plane (abduction/adduction) was identified by the concentric appearance of radiographic arcs formed by the capitellum, trochlear sulcus, and medial trochlear flange. Using these radiographic indices, three orthopaedic surgeons were able to fluoroscopically align the elbow along the axis of rotation with an accuracy of 3.7+/-1.8 degrees. These results are immediately applicable to fluoroscopic identification of the elbow axis. This technique can be used to increase the accuracy of hinge placement during application of hinged external fixation or distraction arthroplasty.     

Reliability of active range-of-motion measurement of the rotation in the forearm: comparison of three measurement devices

AIM: The aim of this study is to prove the intra- and interobserver reliability of three different methods to measure the active range-of-motion in the forearm. METHODS: These three different methods were tested on forty volunteers. In the first method pictures were made in full supination and pronation, measurement of the two angles was performed with a dedicated software. Active range-of-motion was defined as the magnitude of forearm rotation between maximum pronation and supination. The second method used a standard goniometer. The third method of assessment used a gravity goniometer (plurimeter). We randomised both the side of the patient to be examined and the sequence of the methods. Two examiners measured subsequently the range-of-motion twice with these three devices. RESULTS: We found a significant intraobserver reproducibility with the gravity goniometer. There was no significance with the goniometer or pictures. The intraobserver reproducibility of the latter two methods was poor. The interobserver reproducibility of the gravity goniometer and pictures was significant, for the goniometer it was poor. Agreement between the pictures and gravity goniometer assessment of the range-of-motion was good. None of these two methods was significantly correlated with the goniometer assessment. CONCLUSION: For reproducibility of measurement of range-of-motion in the forearm the gravity goniometer is the best method, although the measured values were 5 % greater.     

The kinematic elbow axis as a parameter to evaluate total elbow replacement: A cadaver study of the iBP elbow system

Malpositioning of prosthetic implants leads to biomechanical changes, often resulting in deteriorating functional outcome. This emphasizes the relevance of evaluating the surgical process of inserting the prostheses. This study tested to what extent the iBP elbow prosthesis and its alignment tools enabled a surgeon to reconstruct normal joint kinematics. It demonstrates the use of the kinematic elbow axis as an evaluation tool. An electromagnetic tracking device registered controlled passive elbow flexion of 10 embalmed upper extremities. The position and direction of the preoperative and postoperative kinematic elbow axes were established with the use of helical axes and compared. The postoperative position of the elbow axis differed from the preoperative axis because of limitations of the alignment tools. Suggestions for adjustment of the alignment tools are made. The direction of the imposed resection plane was correct; therefore, the direction of the postoperative elbow axis corresponded with the direction of the preoperative axis.     

Effects of elbow flexion and forearm rotation on valgus laxity of the elbow

BACKGROUND: Clinical evaluation of valgus elbow laxity is difficult. The optimum position of elbow flexion and forearm rotation with which to identify valgus laxity in a patient with an injury of the ulnar collateral ligament of the elbow has not been determined. The purpose of the present study was to determine the effect of forearm rotation and elbow flexion on valgus elbow laxity. METHODS: Twelve intact cadaveric upper extremities were studied with a custom elbow-testing device. Laxity was measured with the forearm in pronation, supination, and neutral rotation at 30 degrees, 50 degrees, and 70 degrees of elbow flexion with use of 2 Nm of valgus torque. Testing was conducted with the ulnar collateral ligament intact, with the joint vented, after cutting of the anterior half (six specimens) or posterior half (six specimens) of the anterior oblique ligament of the ulnar collateral ligament, and after complete sectioning of the anterior oblique ligament. Laxity was measured in degrees of valgus angulation in different positions of elbow flexion and forearm rotation. RESULTS: There were no significant differences in valgus laxity with respect to elbow flexion within each condition. Overall, for both groups of specimens (i.e., specimens in which the anterior or posterior half of the anterior oblique ligament was cut), neutral forearm rotation resulted in greater valgus laxity than pronation or supination did (p < 0.05). Transection of the anterior half of the anterior oblique ligament did not significantly increase valgus laxity; however, transection of the posterior half resulted in increased valgus laxity in some positions. Full transection of the anterior oblique ligament significantly increased valgus laxity in all positions (p < 0.05). CONCLUSIONS: The results of this in vitro cadaveric study demonstrated that forearm rotation had a significant effect on varus-valgus laxity. Laxity was always greatest in neutral forearm rotation throughout the ranges of elbow flexion and the various surgical conditions. CLINICAL RELEVANCE: The information obtained from the present study suggests that forearm rotation affects varus-valgus elbow laxity. Additional investigation is warranted to determine if forearm rotation should be considered in the evaluation and treatment of ulnar collateral ligament injuries of the elbow joint.     

Surgeon accuracy in the selection of the flexion-extension axis of the elbow: an in vitro study

The incorrect determination of the flexion-extension axis of the elbow may result in poor clinical outcomes for patients undergoing ligament repairs, joint arthroplasties, and procedures requiring articulated external fixators. The variability in the selection of the flexion-extension axis based on a visual approximation of bony landmarks on the distal humerus was studied within a group of surgeons. Three surgeons of different experience levels independently selected points through which they believed the flexion-extension axis passed on the medial and lateral surfaces of 23 distal humeri. One surgeon repeated the point selection on three separate occasions. These surgeon points were compared with an axis calculated by use of a computer-assisted method that relied on the centers of the trochlear sulcus and capitellum via digitization of these structures. Relative to the computer-generated flexion-extension axis, the error in the surgeons' selections resulted in a mean frontal plane angle of 1.5 degrees +/- 3.0 degrees valgus (range, 6.3 degrees varus to 9.6 degrees valgus) and a coronal plane angle of 1.6 degrees +/- 3.3 degrees external rotation (range, 8.3 degrees internal rotation to 10.2 degrees external rotation). These results suggest that the use of a computer-assisted surgical technique will allow a more accurate determination of the flexion-extension axis of the elbow, which may lead to improved clinical outcomes in patients treated with ligament repairs or reconstructions, elbow arthroplasties, or articulated external fixators.     

The variability in the external rotation axis of the distal femur: an MRI-based anatomical study

Commonly used total knee arthroplasty (TKA) systems utilising measured resection techniques default to 5°–7° valgus for the distal cut relative to the anatomical axis and 3° external rotation of the femoral component relative to posterior condylar axis (PCA). Rotational errors of the femoral component are associated with pain, patella maltracking and a poorer outcome. We analysed MRI scans from patients undergoing TKA using patient-specific instrumentation to assess coronal and rotational alignment from landmarks identified on the scans. One hundred and eight scans in 59 males and 49 females were studied with age range 35–93 years (mean 67.9 years). We found 91 % of patients had a femoral valgus angle between 5° and 7° (mean angles 5.9°), while only 24 % had an external rotation angle between 2.5° and 3.5° relative to PCA. There was no statistical significance in rotation between males and females although outliers tended to be female. Mean Whiteside’s angle was 92.9° (87.8–98). This study highlights the variations in external rotation between patients undergoing TKA using the PCA as a reference for rotation. This may be a contributing factor in implant malalignment and patient dissatisfaction.     

Radiographic changes at the elbow in primary osteoarthritis: a comparison with normal aging of the elbow joint

A retrospective case-control study was undertaken to evaluate the pathologic radiographic changes that occur in primary osteoarthritis of the elbow. The radiographs of 50 patients with primary osteoarthritis of the elbow were compared with an age- and sex-matched control group to distinguish those features specific to elbow osteoarthritis from those occurring as a result of normal aging. We assessed 100 radiographs (50 anteroposterior and 50 lateral views) in both the study and control groups for 10 radiographic features. In the osteoarthritic group, osteophytes of the olecranon (96%), coronoid process (90%), radial head (86%), and coronoid and radial fossae (64%) were the most frequent findings. Joint space narrowing occurred predominantly at the radiocapitellar joint (58%) and was more common than at the ulnotrochlear joint (16%). Thickening of the olecranon fossa membrane was noted in 68%. In the age- and sex-matched control group, coronoid osteophytes occurred in 36% of cases, but the other features were rarely observed.     

Determination of the abduction-adduction axis of rotation at the human knee: helical axis representation.

This study used a finite helical axes representation to derive the axis of rotation of the human knee in the frontal plane for the neutral flexion/extension posture during resting and no load-bearing conditions. The three-dimensional finite helical axis pathway of the tibia relative to the femur was computed by passively adducting/abducting the lower limb via a servomotor system. Knee joint movements as a result of the positional perturbations were captured with an active marker kinematic tracking system. Contrary to traditional assumptions used in studies conducted under a similar experimental paradigm, our results indicated that the knee joint center, defined as the intercept point between the finite helical axis and the mid-coronal plane of the distal femur, was located within the femoral notch for a wide range of abduction and adduction angles (6 degrees abduction to 6 degrees adduction angles). Our data also indicated that at the neutral posture of the knee, the helical axes directions change as a function of the abduction/adduction perturbation angle. These findings are not only essential to error minimization during joint moment calculations, but can also facilitate new biomechanical interpretations of, for example, the functional role of the quadriceps and patellofemoral joint mechanics to overall knee stability in the medial-lateral direction.     

Variation in the position and orientation of the elbow flexion axis

We analysed the axis of movement in the normal elbow during flexion in vivo using radiostereometric analysis (RSA). The results show an intraindividual variation in the inclination of the axis ranging from 2.1 degrees to 14.3 degrees in the frontal and from 1.6 degrees to 9.8 degrees in the horizontal plane analysed at 30 degrees increments. The inclination of the mean axis of rotation varied within a range of 12.7 degrees in the frontal and 4.6 degrees in the horizontal plane. In both planes, the mean axes were located close to a line joining the centres of the trochlea and capitellum. The intra- and interindividual variations of the axes of flexion of the elbow were greater than previously reported. These factors should be considered in the development of elbow prostheses.     

Surgery for rheumatoid arthritis of the elbow: a comparison of radial-head excision and synovectomy with total elbow replacement.

The results of total elbow replacement (TER) in 45 elbows of 38 patients with rheumatoid arthritis were compared with results of radial head excision with synovectomy (RHES) in 45 age-matched patients treated in the same unit. The groups were similar with respect to duration of disease and preoperative clinical status, although pain was of longer duration and slightly more severe in the TER group. Failure was defined as the onset of moderate or severe pain after surgery or revision surgery for any reason. Reduction in pain was greater after TER than after RHES (P < .05). Recurrence of pain was common after RHES but was not seen after TER. Movement increased by a similar amount in each group. Complications were more frequent and more serious after TER (4 dislocations, 4 ulnar nerve dysfunctions, 1 significant wound breakdown) than after RHES (2 ulnar nerve dysfunctions, 1 transient wound discharge). Complications after TER were most common in patients who had previous RHES. On survival analysis, TER results were better than RHES results in each successive year. Cumulative survival rates at 10 years were 85% for TER and 69% for RHES, but the difference in rates was not statistically significant. In the medium term, TER relieves pain more reliably than RHES and its use is justified despite the greater risk of complications. In view of the paucity of long-term results for TER, RHES may retain a role in younger patients or in those whose symptoms are related mainly to the radiohumeral joint.     

Validity of palpation of the C1 transverse process: comparison with a radiographic reference standard

Objectives:

Primary goal: to determine the validity of C1 transverse process (TVP) palpation compared to an imaging reference standard.

Methods:

Radiopaque markers were affixed to the skin at the putative location of the C1 TVPs in 21 participants receiving APOM radiographs. The radiographic vertical distances from the marker to the C1 TVP, mastoid process, and C2 TVP were evaluated to determine palpatory accuracy.

Results:

Interexaminer agreement for radiometric analysis was “excellent.” Stringent accuracy (marker placed ±4mm from the most lateral projection of the C1 TVP) = 57.1%; expansive accuracy (marker placed closer to contiguous structures) = 90.5%. Mean Absolute Deviation (MAD) = 4.34 (3.65, 5.03) mm; root-mean-squared error = 5.40mm.

Conclusions:

Manual palpation of the C1 TVP can be very accurate and likely to direct a manual therapist or other health professional to the intended diagnostic or therapeutic target. This work is relevant to manual therapists, anesthetists, surgeons, and other health professionals.     

Longitudinal assessment of oxygen cost and velocity in children with myelomeningocele: comparison of the hip-knee-ankle-foot orthosis and the reciprocating gait orthosis.

Oxygen consumption and cost and velocity were evaluated over time in 23 children with myelomeningocele to determine whether differences exist when children walk with hip-knee-ankle-foot orthoses (HKAFOs) versus reciprocating gait orthoses (RGOs). Children using HKAFOs had similar oxygen cost as children using RGOs while achieving a faster velocity. Children walking with HKAFOs into adolescence had a faster velocity and lower oxygen cost than children who discontinued use of their HKAFOs. No significant differences in velocity or oxygen cost were found between children who continued to walk with RGOs and those who discontinued use of their RGOs. Upright ambulation may progress from ambulation with an RGO, when the child's upper extremity strength to mass ratio is low, to an HKAFO when upper extremity strength improves and velocity or keeping up with peers is of concern. Wheelchair mobility should be offered when speed and an energy-efficient method of community mobility are desired.     

The axis of rotation of the ankle joint

The axis of the talo-crural joint was analysed by roentgen stereophotogrammetry in eight healthy volunteers. Examinations were performed at 10 degrees increments of flexion and pronation/supination of the foot as well as medial and lateral rotation of the leg. Results indicate that the talo-crural joint axis changes continuously throughout the range of movement. In dorsiflexion it tended to be oblique downward and laterally. In rotation of the leg, the axis took varying inclinations between horizontal and vertical. All axes in each subject lay close to the midpoint of a line between the tips of the malleoli. Our study indicates that the talo-crural joint axis may alter considerably during the arc of motion and differ significantly between individuals. This prompts caution in the use of hinge axes in orthoses and prostheses for the ankle.     

The assessment of levator trauma: a comparison between palpation and 4D pelvic floor ultrasound

AIMS: Major morphological abnormalities of the pubovisceral muscle are observed in 10-20% of women symptomatic of pelvic floor disorders. Such defects arise in childbirth and are associated with prolapse. While they are clearly evident on 3D ultrasound and MR imaging, such defects can be difficult to detect clinically. We intended to compare findings on palpation with the results of ultrasound imaging. MATERIAL AND METHODS: Fifty-five women were recruited in a prospective observational study and assessed by interview, vaginal examination by a trained pelvic floor physiotherapist, and 3D/4D pelvic floor ultrasound. The vaginal examination involved digital assessment of muscle strength (modified Oxford grading) and morphological abnormalities. The ultrasound examination involved acquisition of volume datasets taken at rest, on Valsalva and pelvic floor muscle contraction. Assessments were undertaken supine and after voiding. Ultrasound operator and physiotherapist were blind to each other's findings. RESULTS: A comparison of 3D ultrasound and palpation was possible in 54 cases. Average Oxford grading was weakly associated with reduction in hiatal dimensions on contraction (r = -0.32, P = 0.024). A marked increase in hiatal dimensions detected on palpation was associated with increased hiatal area on Valsalva (P = 0.027). Defects were observed in 7/54 (13%) on ultrasound and in 10/55 (18%) on palpation. There was poor agreement between the methods, with only two defects picked up equally by both methods. CONCLUSIONS: Palpation of the pubovisceral muscle correlates poorly with 3D/4D pelvic floor ultrasound imaging for the assessment of muscular defects.     

Reliability of range-of-motion measurement in the elbow and forearm

The purpose of this study was to examine intratester, interester, and interdevice reliability of range of motion measurements of the elbow and forearm. Elbow flexion and extension and forearm pronation and supination were measured on 38 subjects with elbow, forearm, or wrist disease by 5 testers. Standardized test methods and a randomized order of testing were used to test groups of patients with universal standard goniometers, a computerized goniometer, and a mechanical rotation measuring device. Intratester reliability was high for all 3 measuring devices. Meaningful changes in intratester range of motion measurements taken with a universal goniometer occur with 95% confidence if they are greater than 6° for flexion, 7° for extension, 8° for pronation, and 8° for supination. Intertester reliability was high for flexion and extension measurements with the computerized goniometer and moderate for flexion and extension measurements with the universal goniometer. Meaningful change in interobserver range of motion measurements was expected if the change was greater than 4° for flexion and 6° for extension with the computerized goniometer compared with 10° and 10°, respectively, if the universal goniometer was used. Intertester reliability was high for pronation and supination with all 3 devices. Meaningful change in forearm rotation is characterized by a minimum of 10° for pronation and 11° for supination with the universal goniometer. Reliable measurements of elbow and forearm arm movement are obtainable regardless of the level of experience when standardized methods are used. Measurement error was least for repeated measurements taken by the same tester with the same instrument and most when different instruments were used.     

An anatomic study of the axis of elbow movement in the coronal plane: Relevance to component alignment in elbow arthroplasty

We have performed an anatomic study on cadaveric material identifying a relationship between the posterior cortex of the distal humerus and the axis of movement of the elbow joint with reference to the coronal plane. This study was performed on 11 cadaveric upper limbs in which the axis of movement relative to the coronal plane was identified and confirmed with an external fixator. The relation between this plane and the tangential plane of the posterior cortex of the distal humerus was investigated. Observations made at points progressively proximal to the humeral epicondyles demonstrated that the tangential plane of the posterior humeral cortex became increasingly inclined medially until it became parallel to the coronal axis of movement of the elbow joint at a point 25 to 35 mm proximal to the medial epicondyle of the humerus. The relevance of this observation to the orientation of the humeral component of a total elbow joint replacement arthroplasty is discussed.