Mark Carl Miller

Midterm Follow-up of Opening-Wedge High Tibial Osteotomy

Background High tibial osteotomy is a valuable option for patients with varus gonarthrosis. To avoid difficulties with closing-wedge osteotomies, medial opening-wedge high tibial osteotomies have been advocated. Hypothesis Opening-wedge high tibial osteotomy is a good option in highly active patients with varus gonarthrosis who would like to delay or prevent progression to total knee arthroplasty without activity restrictions. Study Design Case series; Level of evidence, 4. Methods Twenty consecutive patients with varus gonarthrosis were treated with a medial opening-wedge high tibial osteotomy using the Puddu plate and allograft bone graft for a prospective study (14 men and 6 women; average age, 49.4 years [range, 36-67 years]). Gait analysis was performed preoperatively and at 6 months postoperatively. Preoperative radiographs, subjective ratings, and knee scores (Lysholm and Hospital for Special Surgery [HSS] scores) were obtained. At 2 years postoperatively and at the latest follow-up visit (average, 8.3 years), the subjective ratings and knee scores were repeated. Results Gait analysis revealed an abnormal weightbearing pattern preoperatively with the vertical ground-reaction force. The postoperative vertical ground-reaction force revealed a normal double peak pattern. The preoperative adduction moment was 29% greater than the 6-month postoperative adduction moment. The preoperative varus averaged 3.6° and was corrected to an average of 7.5° of valgus postoperatively. All patients subjectively rated their preoperative knee as poor. At 2 years postoperatively, most patients (14) rated their knee as good, with 5 excellent and only 1 fair rating. The average preoperative Lysholm and HSS knee scores were 54.2 and 75.9, respectively, compared with the 2-year postoperative averages of 89.1 and 92.7, respectively. At 8 years postoperatively, there was 70% survivorship with 42% of patients rating their knees as good or excellent. Five patients (25%) had undergone total knee arthroplasty. Lysholm and HSS knee scores were 83.0 and 86.8, respectively, for the surviving knees at 8 years postoperatively. Conclusion Medial opening-wedge high tibial osteotomy produces good results in the midterm. After the osteotomy, a more normal appearing weightbearing pattern with double peaks was seen. The adduction moment significantly decreased, resulting in less contact pressure through the medial degenerative compartment of the knee. The authors recommend medial opening-wedge high tibial osteotomy for young patients with varus alignment and medial compartment arthritis to allow this patient population to remain highly active and delay progression to total knee arthroplasty without activity restrictions.

The effect of component placement on knee kinetics after arthroplasty with an unconstrained prosthesis.

The mechanical success of a total knee replacement demands stable patellar tracking without subluxation and, stable tracking, in turn, can depend largely on the medial‐lateral forces restraining the patella. Patellar button medialization has been advocated as a means of reducing subluxation, and experimental evidence has shown femoral component rotation also affects medial—lateral forces. Surgeons have choices in femoral component rotation and patellar button medialization and must frequently make intra‐operative decisions concerning component placement because of anatomical variations among patients. Thus, in seeking to minimize medial—lateral patellar force, we examined the effects of patellar button medialization and external femoral component rotation. The study used an unconstrained total knee system implanted in nine cadaveric specimens tested on a knee simulator operating through flexion angles up to 100°. Tests included all combinations of external femoral component rotation of 0°, 2.5°, and 5° and patellar placement at the geometric center and at 3.75 mm medial to the geometric center. A video‐based motion analysis system tracked patellar and tibial kinematics while a six‐component load cell measured patellofemoral loads. Repeated measures analysis of variance revealed a statistically significant decrease in the average medial‐lateral force with button medialization but no significant change with femoral component rotation. Neither femoral component rotation nor patellar button medialization had an effect on the normal component of the patellar reaction force. External femoral component rotation did cause significant increases in lateral patellar tilt, in tibial varus angle, and in external tibial rotation. Button medialization caused significant increases in lateral patellar tracking, lateral patellar tilt and external tibial rotation. The results in medial‐lateral patellar forces quantify the benefit of patellar button medialization and discount any benefit of femoral rotation. The change in tibial kinematics with patellar button medialization and femoral component rotation cannot be measured in vivo with current technology, and the precise clinical implications are unknown.

Radial head replacement with a bipolar system: a minimum 2-year follow-up

BACKGROUND We report the short-term results of a cohort of patients undergoing radial head replacement using a novel radial head prosthesis with a smooth, unfixed, telescoping stem and a bipolar design after a mean follow-up of 34 months (range, 24-48 months). MATERIALS AND METHODS Patients were assessed using clinical and radiographic examination as well as with standardized outcome measures. Thirty implants (29 patients) were available for review. RESULTS At final follow-up, the average Mayo Elbow Performance Index Score was 92.1 and the Disabilities of the Arm, Shoulder, and Hand Score was 13.8. Clinical examination revealed significant differences between operative and nonoperative sides for flexion/extension and pronation/supination. Radiographic measurement of medial and lateral ulnohumeral spaces revealed re-establishment of a congruent elbow joint. No significant arthritic changes were identified at the radiocapitellar joint. Minimal angular migration of the implant in the proximal radial shaft was observed over time. Complications included 1 patient requiring temporary placement of a hinged external fixator for instability and 1 patient requiring revision surgery at 4 weeks. CONCLUSION This review demonstrates that a bipolar radial head prosthesis with a smooth stem and telescoping neck effectively restores stability to elbows with a comminuted radial head fracture and valgus instability. To date, this is the largest reported outcome analysis of bipolar radial head replacement in the literature.

Repaired distal biceps magnetic resonance imaging anatomy compared with outcome

BACKGROUND This study examined the magnetic resonance imaging (MRI) appearance of an anterior incision distal biceps tendon repair and evaluated the association between appearance and outcome. MATERIALS AND METHODS Nineteen patients were randomly recruited to undergo an elbow MRI from a single-surgeon series of distal biceps repairs using an anterior approach. Tendon healing was evaluated by the integrity of the repair, the amount of heterogeneity within the tendon substance, and the presence of heterotopic bone. The angle of tendon insertion on the tuberosity was used to quantify the tendon location from the MRI in the patients and in 10 healthy volunteers. All patients completed the Disabilities of Arm, Shoulder and Hand (DASH) and a visual analog pain scale (VAPS), and 17 patients underwent isometric supination strength testing. MRI findings were statistically compared with the outcome scores. RESULTS All of the repairs healed to cortical bone. High intrasubstance heterogeneity or heterotopic bone was present in 11 patients (58%). The insertion site angle of the repaired tendons was 73° more anterior than the uninjured controls (P < .001). Average DASH was 7.7 (range, 0-49.2) and VAPS was 0.7 (range, 0-5). At 60° of forearm supination, supination strength was 67% of the uninjured side (P < .01). No significant differences in DASH or VAPS scores were found between groups based on tendon appearance. CONCLUSIONS The distal biceps tendon predictably heals to cortical bone but demonstrates a wide variability in overall morphology that does not influence DASH or VAPS scores. A significant decrease in strength at 60° of supination appears to be an effect of an anterior tendon reattachment location.

Anatomic and biomechanical analysis of the short and long head components of the distal biceps tendon.

HYPOTHESIS The short head bundle of the distal biceps tendon is more efficient at elbow flexion, and the long head is more efficient at forearm supination. METHODS The short and long head bundles of the distal biceps tendon were separated to the bicipital tuberosity in 6 cadavers. The area and centroid of each bundle insertion were computed from surface points measured within each footprint. Each bundle was individually loaded. The supination torque and flexion load generated were recorded at 90° of elbow flexion. The slope of the torque generated versus biceps load was used to define the supination moment arm. The ratio of the flexion load generated to biceps load applied was used to define the relative flexion efficiency. RESULTS The short head insertion was positioned distal and anterior relative to the long head and typically included the apex of the tuberosity. The areas of the long and short heads were 59 ± 15 and 94 ± 44 mm(2) (P = .07), respectively. The long head moment arm was significantly higher in supination. The short head had a significantly higher moment arm in neutral and pronation. The ratio of the flexion load to biceps load was 15% higher for the short head. CONCLUSION The short and long heads of the biceps have distinct insertions. The short heads insertion allows it to be relatively more efficient at elbow flexion at 90°. In the neutral and pronated forearm, the short head is the relatively more efficient supinator. In the supinated forearm, the long head becomes relatively more efficient at supination.

The effect of biceps reattachment site.

BACKGROUND We hypothesize that an anatomic repair of the distal biceps tendon would recreate native tendon moment arm and forearm rotation, while a nonanatomic insertion would compromise moment arm and forearm rotation. METHODS Isometric supination torque was measured at 60° of pronation, neutral, and 60° of supination for the native distal biceps tendon and 4 repair points in 6 cadaveric specimens using a computer controlled elbow simulator. The slope of the regression line fitted to the torque versus biceps load data was used to define the moment arm for each attachment location. Range of motion testing was performed by incrementally loading the biceps, while measuring the supination motion generated using a digital goniometer. RESULTS Tendon location and forearm position significantly affected the moment arm of the biceps (P < .05). Anatomic repair in all forearm positions showed no significant difference from the native insertion. Moment arm for an anterior center repair was significantly lower in supination (-97%) and neutral (-27%) and also produced significantly less supination motion. No difference was observed between all tendon locations in pronation. CONCLUSIONS Reattachment of the biceps to its anatomic location, as opposed to a more anterior central position, is critical in reestablishing native tendon biomechanics. Clinically, these findings would suggest that patients with a biceps repair might experience the most weakness in a supinated position without experiencing a deficit in the pronated forearm.

The contracted elbow: is ulnar nerve release necessary?

BACKGROUND Prophylactic release of the ulnar nerve in patients undergoing capsular release for severe elbow contractures has been recommended, although there are limited data to support this recommendation. Our hypothesis was that more severely limited preoperative flexion and extension would be associated with a higher incidence of postoperative ulnar nerve symptoms in patients undergoing capsular release. MATERIALS AND METHODS We conducted a retrospective review of 164 consecutive patients who underwent open or arthroscopic elbow capsular release for stiffness between 2003 and 2010. The ulnar nerve was decompressed if the patient had preoperative ulnar nerve symptoms or a positive Tinel test. Preoperative and postoperative range of motion and incidence of ulnar nerve symptoms were recorded. RESULTS The mean improvement in the arc of motion of was 36.7°. New-onset postoperative ulnar nerve symptoms developed in 7 of 87 patients (8.1%) who did not undergo ulnar nerve decompression; eventually, 5 of these patients with persistent symptoms underwent ulnar nerve decompression. The rate of developing postoperative symptoms was higher if patients had preoperative flexion ≤ 100° (15.2%) compared with those with preoperative flexion >100° (3.7%). There was no association between preoperative extension or gain in motion arc and postoperative symptoms. CONCLUSIONS The overall rate of ulnar nerve symptoms after elbow contracture release was low if ulnar nerve decompression was performed in patients with preoperative symptoms or a positive Tinel test. There was a higher rate of ulnar nerve symptoms in patients with more severe contractures (≤ 100° of preoperative flexion), which did not reach statistical significance.

Plain Radiographs Are Inadequate to Identify Overlengthening With a Radial Head Prosthesis

PURPOSE A correctly sized radial head implant helps restore more normal elbow motion and load distribution and allows the collateral ligaments to heal in an anatomic position. No single method of measurement has been agreed on. We hypothesized that plain radiographs could be used to evaluate the appropriate length of a radial head prosthesis when we simulated different patterns of ligament disruption. METHODS Osteotomies of the medial and lateral condyles were created in 6 cadaver specimens to simulate 4 conditions: ulnar collateral ligament (UCL) and lateral ulnar collateral ligament (LUCL) intact, UCL intact, LUCL intact, and UCL and LUCL disrupted. Radial heads were resected and replaced with correctly or incorrectly sized monopolar radial head implants. Radiographs were taken after simulated ligament injury with a radial head prosthesis that was either 2 mm too short, the appropriate length, or too long by either 2 or 4 mm. Measurements were recorded between radiographic markers to determine ulnohumeral joint displacement. A 4 x 4 x 2 repeated-measures analysis of variance was performed, as well as post hoc analyses using Tukeys honest significant difference test, to determine statistically significant changes in our radiographic measurements. RESULTS Results showed that disruption of at least 1 ligament alters the ulnohumeral joint separation on the lateral but not on the anteroposterior radiograph. Overlengthening the radial head did not result in a statistically significant change in ulnohumeral space. CONCLUSIONS Replicating radial length is an important but sometimes difficult step during radial head replacement. Standard radiographic assessment of the ulnohumeral joint will not demonstrate marked changes in the ulnohumeral space when the implant is underlengthened by 2 mm or overlengthened by as much as 4 mm, as long as the joint remains located. Disruption of at least 1 collateral ligament alters the ulnohumeral joint separation on the lateral but not on the anteroposterior radiograph.

Proprioception after total ankle arthroplasty.

Background: Total ankle arthroplasty (TAA) is becoming an effective treatment for end-stage ankle arthritis. It is unknown if TAA alters the patients ability to sense ankle joint position. Materials and Methods: Thirteen unilateral TAA patients with a minimum of 2-years followup completed proprioceptive testing of the TAA and the contralateral side. The task was to reproduce a given ankle angle using a joystick-driven device while the lower limb was obscured from view. Nine angles were tested, including two angles in dorsiflexion, three in plantarflexion, two in inversion, and two in eversion. A repeated-measures ANOVA was used to evaluate the results. Results: No statistically significant differences between the TAA ankle and the contralateral side were found. Conclusion: TAA does not cause a change in proprioceptive abilities in arthritis patients when compared to the contralateral, unaffected side in a small sample of unilateral patients. Surgeons and rehabilitation professionals may use this information when designing rehabilitation plans following the insertion of a TAA. Level of Evidence: III, Retrospective Case Series

Computational study of human head response to primary blast waves of five levels from three directions.

Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.