Surgical release of elbow-capsular contracture in pediatric patients

Nine pediatric patients with elbow-capsular contractures were treated by surgical release. Six patients had sustained prior trauma and three patients had medical conditions leading to capsular contracture. A lateral approach was used to release the anterior and posterior capsules, as well as to remove sites of bony impingement. All patients were treated with postoperative range of motion and splinting, with six patients receiving a continuous brachial plexus block to facilitate therapy. Average loss of extension improved from 47 to 15 degrees, mean angle of flexion from 102 to 124 degrees, and total arc of motion increased from 55 to 108 degrees at an average of 17 months after surgery. Complications included wound infection and catheter-site erythema.     

Biomechanical evaluation of the medial collateral ligament of the elbow

Anatomical dissection and biomechanical testing were used to study twenty-eight cadaveric elbows in order to determine the role of the medial collateral ligament under valgus loading. The medial collateral ligament was composed of anterior, posterior, and occasionally transverse bundles. The anterior bundle was, in turn, composed of anterior and posterior bands that tightened in reciprocal fashion as the elbow was flexed and extended. Sequential cutting of the ligament was performed while rotation caused by valgus torque was measured. The anterior band of the anterior bundle was the primary restraint to valgus rotation at 30, 60, and 90 degrees of flexion and was a co-primary restraint at 120 degrees of flexion. The posterior band of the anterior bundle was a co-primary restraint at 120 degrees of flexion and a secondary restraint at 30 and 90 degrees of flexion. The posterior bundle was a secondary restraint at 30 degrees only. The reciprocal anterior and posterior bands have distinct biomechanical roles and theoretically may be injured separately. The anterior band was more vulnerable to valgus overload when the elbow was extended, whereas the posterior band was more vulnerable when the elbow was flexed. The posterior bundle was not vulnerable to valgus overload unless the anterior bundle was completely disrupted. The intact elbows rotated a mean of 3.6 degrees between the neutral position and the two-newton-meter valgus torque position. Cutting of the entire anterior bundle caused an additional 3.2 degrees of rotation at 90 degrees of flexion, where the effect was greatest. CLINICAL RELEVANCE: Physical findings in a patient who has an injury of the anterior bundle may be subtle, and an examination should be performed with the elbow in 90 degrees of flexion for greatest sensitivity. As the anterior bundle is the major restraint to valgus rotation, reconstructive procedures should focus on anatomical reproduction of that structure. Parallel limbs of tendon graft placed from the inferior aspect of the medial epicondyle to the area of the sublimis tubercle will simulate the reciprocal bands of the anterior bundle. Temporary immobilization with the elbow in flexion may relax the critically important anterior band of the reconstruction during healing.     

Total elbow arthroplasty as primary treatment for distal humeral fractures in elderly patients

We retrospectively reviewed the results of primary total elbow arthroplasty for the treatment of an acute fracture of the distal aspect of the humerus in twenty consecutive patients (twenty-one elbows) who had a mean age of seventy-two years (range, forty-eight to ninety-two years) at the time of the injury. The patients were managed between November 1982 and October 1992. The presence of rheumatoid arthritis in nine patients (ten elbows) influenced the choice of treatment. The mean interval between the injury and the total elbow arthroplasty was seven days (range, one to twenty-five days). The mean duration of postoperative hospitalization was seven days (range, four to thirteen days). The mean duration of follow-up was 3.3 years (range, three months to 10.5 years). All patients were followed for a minimum of two years or until the time of death; the duration of follow-up was less than two years for three patients who died. None of the patients were lost to follow-up. Twenty implants were intact at the latest follow-up examination. One patient had a revision total elbow arthroplasty twenty months after the index procedure because of a fracture of the ulnar component sustained in a fall on the outstretched arm. On the basis of the Mayo elbow performance score, fifteen elbows had an excellent result and five had a good result; there were inadequate data for one elbow. There were no fair or poor results. The mean arc of flexion was 25 to 130 degrees. There was no evidence of loosening on the radiographs. Postoperative complications included fracture of the ulnar component in one patient, ulnar neurapraxia in three, and reflex sympathetic dystrophy in one. The results suggest that total elbow arthroplasty can be an alternative form of treatment of a severely comminuted fracture of the distal aspect of the humerus in older patients even in the presence of rheumatoid arthritis. This procedure is not an alternative to osteosynthesis in younger patients.     

In vivo anteroposterior femorotibial translation of total knee arthroplasty: a multicenter analysis

A study was conducted to determine in vivo femorotibial contact patterns for subjects having a posterior cruciate retaining or posterior cruciate substituting total knee arthroplasty. Femorotibial contact of 72 subjects implanted with a total knee replacement, performed by five surgeons, was analyzed using video fluoroscopy. Thirty-one subjects were implanted with a posterior cruciate retaining total knee replacement with a flat polyethylene posterior lipped insert, 12 with a posterior cruciate retaining total knee replacement with a curved insert, and 29 with a posterior cruciate substituting total knee replacement. Each subject performed successive deep knee bends to maximum flexion. Video images at 0 degree, 30 degrees, 60 degrees, and 90 degrees flexion were downloaded onto a workstation computer. Femorotibial contact paths were determined for the medial and lateral condyles using an interactive model fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative. Analysis of average femorotibial contact pathways of both posterior cruciate retaining designs revealed posterior femorotibial contact in full extension with anterior translation of femorotibial contact commonly observed in midflexion and terminal flexion. In posterior cruciate substituting designs, anterior femoral translation was seen medially at 30 degrees to 60 degrees flexion but rarely was observed laterally. Posterior femoral rollback laterally from full extension to 90 degrees flexion was seen in 100% of subjects implanted with a posterior cruciate substituting total knee replacement, versus 51.6% (posterior lipped polyethylene insert) and 58.3% (curved insert) of those with a posterior cruciate retaining total knee replacement. Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs, and conversely showing an average anterior femoral translation with knee flexion. Posterior femoral rollback, less than in normal knees, routinely was observed in posterior cruciate substituting total knee arthroplasty, attributed to engagement of the femoral component cam with the tibial post. The abnormal anterior femoral translation observed in posterior cruciate retaining total knee arthroplasty may be a factor in premature polyethylene wear observed in retrieval studies.     

Mechanical distraction for treatment of severe knee flexion contractures

Ten patients (14 knees) with severe knee flexion contractures were treated by gradual mechanical distraction using either the Ilizarov or Orthofix external fixator. Range of motion improved from an average flexion contracture of 60 degrees before surgery to 16 degrees at the follow-up evaluation. Range of motion results were graded good or excellent in five knees, fair in two knees, and poor in three knees. Average total arc of motion remained essentially unchanged when comparing the preoperative (59 degrees) with the follow-up results (63 degrees). However, the functional position of this arc improved significantly. Problems encountered included a "rebound" phenomena after frame removal, with loss of the temporarily increased total arc of motion. The role of hamstring tenotomy and radical posterior knee release remains unclear.     

Natural history of uncorrected flexion contractures following total knee arthroplasty

Over a 2-year period, 29 patients were identified that had preoperative flexion contractures less than 30 degrees and were not fully corrected to neutral following total knee arthroplasty. They were followed after surgery at 3, 6, and 12 months, and yearly thereafter with complete clinical and roentgenographic examinations to determine the natural history of the flexion contracture and its effect on the clinical outcome. The mean age of the 10 women and 19 men was 66 years (range, 47-80 years). The mean preoperative flexion contracture was 11 degrees (range, 5 degrees-30 degrees). The mean follow-up period was 33 months (range, 24-60 months). The mean values of the flexion contractures at each follow-up period were; immediately after surgery, 10.5 degrees; at 3 months, 5 degrees; at 6 months, 2 degrees; at 12 months, 1 degree; and at 24 months, 1 degree (P < .0001). Resolution of the flexion contracture did not vary between patients under and over the age of 65 years. There was no statistically significant difference in the residual flexion contracture when knees with preoperative contractures from 0 degrees to 14 degrees and 15 degrees to 30 degrees were compared. The clinical outcome was not affected by the residual flexion contracture after 6 months of follow-up evaluations. Significant improvements can occur after surgery with rehabilitation, and it appears that complete intraoperative correction is not necessary. There appears to be no difference in the natural history of flexion contractures with regard to age or severity up to 30 degrees.     

Anterior cruciate ligament reconstruction. The effect of tibial tunnel placement on range of motion

In 111 patients who had anterior cruciate ligament reconstructions, postoperative radiographic measurements of anterior to posterior and medial to lateral location of the tibial tunnels were correlated with the final range of motion achieved. In the 25 patients with extension deficits of 10 degrees or more, placement of the tibial tunnel was more anterior (average, anterior 23% of the tibia) than in the remaining 86 patients with extension deficits of < 10 degrees (average, anterior 29% of tibia). This difference was statistically significant with P < 0.001. Logistic regression analysis revealed that the more anterior the placement of the tibial tunnel, the greater the loss of both flexion (P = 0.01) and extension (P = 0.002). In the 21 patients with full extension but flexion < 130 degrees, placement of the tibial tunnel tended to be more medial (average, medial 40% of the tibia) than in the 65 patients without flexion deficit (average, medial 45% of the tibia). We conclude that placement of the tibial tunnel in the "eccentric," anteromedial position may contribute to the development of flexion and extension deficits after anterior cruciate ligament reconstruction.     

Ibutilide: an antiarrhythmic agent for the treatment of atrial fibrillation or flutter

The results of nineteen semiconstrained modified Coonrad-Morrey total elbow arthroplasties performed in nineteen patients to treat instability were evaluated at an average of seventy-two months (range, twenty-five to 128 months) postoperatively. Preoperatively, all patients had either a flail elbow or gross instability of the elbow that prevented useful function of the extremity. The instability of sixteen elbows was the result of a traumatic injury or of the treatment of such an injury. The most recent result was satisfactory for sixteen elbows and unsatisfactory for three. The average overall Mayo elbow performance score increased from 44 points preoperatively to 86 points postoperatively. At the most recent follow-up examination, no elbow was unstable. The average arc of flexion was from 25 degrees (range, 0 to 60 degrees) to 128 degrees (range, 30 to 142 degrees), which represented a 58-degree increase from the preoperative average arc. Sixteen patients had little or no pain after the arthroplasty. There were four complications in four patients. Three complications (loosening of the humeral component in one patient and a fracture of the ulnar component in two) occurred postoperatively; all three were treated with a revision procedure. The other complication (a fracture of the olecranon) occurred intraoperatively and was treated with tension-band fixation; the most recent outcome was not affected. Radiographically, one patient had complete (type-V) radiolucency about the humeral component. None of the nine patients for whom true anteroposterior radiographs were available had evidence of wear of the bushings. The bone graft behind the anterior flange of the humeral prosthesis was mature in fourteen elbows, incomplete in two, and resorbed in two. One patient was excluded from this analysis because radiographs were not available. Instability of the elbow resulting in the inability to use the extremity is a challenging clinical situation. However, in patients who are more than sixty years old and in selected patients who are less than sixty years old but who have extensive loss of bone as a result of severe injury, have had multiple operations, or have rheumatoid arthritis, total elbow arthroplasty with a linked, semiconstrained prosthesis reestablishes a mobile, stable joint without premature loosening or failure of the components. In our experience, the use of customized implants, maintenance of the muscular attachments to the epicondyles, and reconstruction of the epicondyles to the implant were unnecessary.     

Sacrospinalis muscle-pedicle bone graft in posterolateral fusion for spondylolisthesis

From 1984 to 1995, 68 ankylosed elbows and 11 which were unstable after trauma were replaced in India by Baksi sloppy hinge prostheses. The mean age of the patients was 28.6 years (17 to 70) and the mean follow-up 9.6 years (2 to 13.5). Of the 68 ankylosed elbows, 59 (87%) regained a mean arc of painless movement of 88.5 degrees (27 to 115). The mean improvement of supination was 24 degrees and of pronation 16.5 degrees . There were 54 good results (80%), eight fair and three poor. There were two complete failures due to infection, and one due to a broken humeral stem. Of the 11 unstable elbows, the nine with good results had a mean arc of 125 degrees (15 to 140) of painless stable movement, with a mean improvement in supination of 26 degrees and of pronation of 19.5 degrees . There was one fair result and one failure due to loosening with subsequent late infection. There were significant complications in 14 cases with infection in seven and aseptic loosening in four. Patients with loosening or late removal of the prosthesis often retained reasonably stable elbow movement because periprosthetic fibrosis had connected the approximated bone ends, and muscle balance had been restored.     

The effect of a flexion contracture of the elbow on the ability to transfer in patients who have quadriplegia at the sixth cervical level

We studied six patients (twelve upper extremities) who had quadriplegia at the sixth cervical level. Our purpose was to evaluate how the loss of terminal extension of the elbow adversely affected the ability of the patient to perform transfers with a sliding board and so-called depression raises (lifting of the body with use of the extended upper extremities to reduce the pressure on the ischial tuberosities). Function of the triceps muscle was considered to be absent in eight upper extremities and present in four. A flexion contracture of the elbow was simulated with use of a specially fabricated, hinged elbow brace. Terminal extension was progressively limited, in 5-degree increments, until the patient was no longer able to perform the transfer or the depression raise. The mean flexion contracture at which the patient could not perform the transfer or the depression raise was approximately 25 degrees when function of the triceps was absent and approximately 50 degrees when function of the triceps was intact. The results of this study emphasize the importance of maintaining the full range of motion of the elbow in a patient who has high-level quadriplegia. In a patient who has quadriplegia at the sixth cervical level who otherwise would be independent with regard to transfer skills and mobility in bed, a flexion contracture of the elbow of approximately 25 degrees or more can result in the loss of a functional level and render the patient as dependent as one who has quadriplegia at the fifth cervical level.     

Apoptosis of tubular epithelial cells in familial juvenile gouty nephropathy

Chronic ruptures of the patellar tendon are uncommon injuries. They are technically difficult to repair because of scar formation, poor quality of the remaining tendon, and quadriceps muscle atrophy and contracture. We report the reconstruction of a chronic patellar tendon rupture with an interesting complication, a tibial stress fracture. The reconstruction was performed 3 months after the injury using an Achilles tendon-bone allograft and reinforcing suprapatellar wire. At 2 weeks postoperatively, the patient had attained full extension and 90 degrees of flexion. Ten months after the index procedure, the patient had range of motion 0 degrees to 120 degrees and was diagnosed with a healing tibial stress fracture. At 17 months postoperatively, the patient had attained full extension, 120 degrees of flexion, and 85% quadriceps strength. The preoperative goals of attaining full range of motion, improving quadriceps strength, obtaining anatomic patellar alignment, and restoring function were obtained despite the complication of a tibial stress fracture. Although this reconstructive procedure is technically demanding, with potential complications, the functional results obtained can be excellent.     

Late correction of malunited intercondylar humeral fractures. Intra-articular osteotomy and tricortical bone grafting

We treated three patients with malunion after comminuted intercondylar fractures of the humerus by intra-articular derotational opening-wedge osteotomy and the insertion of a tricortical iliac bone graft. Two patients required additional operations, including interposition arthroplasty and hardware removal. A mean arc of increased motion of 65 degrees was achieved in flexion and extension in two patients and a more functional arc in the third. Although this is viewed as a salvage procedure in patients who are thought to be too young for elbow arthroplasty, none of the three patients has significant pain and none has required total elbow arthroplasty after an average follow-up of 7.6 years.     

Muscle strength in rheumatoid elbow: quantitative measurement and comparison to Larsen's X-ray grade

Accurate assessment of elbow function is important to determine the total ability of the arm. The purpose of this study was to clarify the relationship between isometric muscle strength of the elbows of patients with rheumatoid arthritis (RA) and Larsen's X-ray evaluation. Fifty-six elbows of 45 RA patients aged 47 to 77 years (mean age, 63 years) were tested. Muscle strength was measured with an isometric torque-cell dynamometer. Test-retest reliability of the dynamometer was proven by measuring 12 elbows of 6 healthy young men. In RA patients, elbow flexion and extension strength decreased in proportion to increases in the severity of Larsen's grades from Grade 1 to 4. However, Grade 5 elbows had greater muscle strength than those in Grade 4. Forearm pronation and supination strength also decreased in proportion to increases in the severity of Larsen's grades from Grade 1 to 5. This quantitative study made it clear that the muscle strength of RA patients' elbows almost completely correlates to X-ray finding according to the grade of Larsen's evaluation based on X-rays. With regard to muscle strength of postoperative elbows, both flexion strength and supination strength after total elbow replacement (TER) were about two times greater than before TER, and after synovectomy it was as great as those in non-operative RA patients of Grade 2.     

Distal realignment of the patellar tendon to correct abnormal patellar tracking

Between January 1980 and January 1994, 31 knees required distal realignment of the extensor mechanism to treat lateral patellar subluxation that could not be corrected with lateral patellar release and vastus medialis advancement during total knee arthroplasty. Fifteen had a preoperative valgus angle of more than 12 degrees, and 16 were undergoing revision total knee arthroplasty. Ten knees had a modified Roux-Goldthwait procedure, 18 had medial tibial tubercle transfer, and three had medial transfer of the medial 1/2 of the patellar tendon. The length of followup ranged from 2 to 16 years. No late patellar subluxations or dislocations have occurred in any of these cases. Three cases of medial tibial tubercle transfer had hematomas develop, with two requiring surgical evacuation; one of these developed a late infection. No fractures or displacements of the tubercle fragment have occurred. No significant patellar complications have occurred in those patients who underwent the modified Roux-Goldthwait procedure or the medial transfer of the medial 1/2 of the patellar tendon. One year after surgery, the mean knee flexion was 113 degrees, four knees had a flexion contracture of 5 degrees, and none had a quadriceps lag.     

A biomechanical evaluation of graft loading characteristics for anterior cervical discectomy and fusion. A comparison of traditional and reverse grafting techniques

STUDY DESIGN: A biomechanical study of graft loading characteristics for anterior cervical discectomy and fusion comparing the amount and location of transmitted forces. OBJECTIVES: To evaluate the difference between traditional iliac grafting and reverse iliac grafting used for anterior cervical discectomy and fusion in the amount and location of forces applied to the grafts. SUMMARY OF BACKGROUND DATA: Traditional fusion after anterior cervical discectomy involves placing a tricortical iliac crest strut into the disc space with the cortical portion facing anteriorly and the cancellous portion posteriorly. Recently, reverse iliac grafting has been introduced in which the cortical portion is placed in the posterior disc space and the cancellous portion in the anterior disc space. There is no biomechanical or clinical study showing an advantage of using one technique over the other. This study is the first to produce data supporting one technique as biomechanically superior. METHODS: Five fresh cadaveric cervical spines were tested using pressure-sensitive film placed between the bone graft and the vertebral endplate after an anterior discectomy was performed. A 10-pound load was applied to the cervical spine at predetermined sagittal positions. Recordings were made at neutral, 10 degrees of flexion, and 10 degrees and 20 degrees of extension after traditional and reverse iliac grafting. RESULTS: Graft forces were identical in both traditional and reverse grafting in the location and amount of force applied. Total force increased to the maximum in flexion and gradually decreased in more extended positions. The location of the forces was completely anterior with flexion, moving to the posterior portion of the graft with positions of extension. With 10 degrees of flexion, the load applied to the grafts was 20.4 N. In the neutral position, the load was 12 N. The loads decreased further with extension with forces of 11 N in 10 degrees extension, and 4 N in 20 degrees of extension. CONCLUSIONS: The optimal position of the tricortical iliac graft for an anterior cervical fusion is with the stronger cortical portion placed in the anterior disc space and the weaker cancellous portion placed in the posterior disc space. In this traditional position, the graft will best resist the loads applied to the cervical spine, preventing graft collapse.     

Range of motion and complications after postburn heterotopic bone excision about the elbow

OBJECTIVE: To review the results of surgical management of heterotopic ossification about the elbow in burned patients. DESIGN: Retrospective analysis with long-term patient follow-up. MATERIALS AND METHODS: Eleven patients with 16 elbows requiring surgery were admitted between January 1, 1982 and December 31, 1993. A posterior approach to the elbow with release of the encased ulnar nerve +/- anterior transposition and transolecranon osteotomy to access extensive bone formation in the olecranon fossa was employed. Eight patients (11 elbows) were available for long-term follow-up conducted at mean 50 +/- 13 months after surgery. Long-term follow-up consisted of measurement of range of elbow motion, as well as clinical assessment of ulnar nerve function. MAIN RESULTS: For the 11 elbows examined postoperatively, the mean range of motion preoperatively in flexion-extension was 11 degrees +/- 5 degrees compared to 89 degrees +/- 12 degrees postoperatively (p < 0.001). Three patients with poor long-term results had ankylosis of the joint preoperatively. Of four patients with ulnar nerve paresis preoperatively, none had ulnar nerve dysfunction at follow-up. Of 16 elbows operated on, four (25%) had postoperative complications. Two suffered soft-tissue breakdown with hardware exposure requiring abdominal flap closure, one early failure of olecranon fixation, and one late infected hardware. CONCLUSIONS: Surgery for both limited range of motion as well as ulnar nerve compression is effective in cases of heterotopic ossification about the elbows of burned patients. Early operative intervention is indicated in progressive disease, particularly ulnar nerve palsy, if soft-tissue quality is adequate. Complications with 25% of elbows suggest that use of olecranon osteotomy for joint access may warrant review.     

Gleno-humeral arthroscopic arthrolysis for shoulder stiffness. Apropos of 26 cases. Société Fran?aise d'Arthroscopie

Shoulder stiffness is a problem which covers many different conditions. In fact there is still a semantic and pathogenetic confusion. The words: capsulite retractile, frozen shoulder, adhesive capsulitis, stiff shoulder contracture have been successively used and this ambiguity renders the literature difficult to interpret. Moreover the cause of the stiffness which depends on the aetiology, is not always clearly known: capsular contraction, capsular adhesion, capsular scarring following trauma or surgery, extra capsular phenomenons in the subacromial bursa, muscles or tendons. MATERIALS AND METHODS: 26 shoulders (25 patients) were reviewed with a follow up of 21 months using the Constant's scoring system. Patients had an average duration of symptoms for 13 months (1 to 27). Pre op passive motion was: abduction: 74 degrees, external rotation: 6 degrees, forward flexion: 84 degrees. The average motion core was 12.9/40. We distinguished three groups: primary frozen shoulder (13 cases) ; bipolar stiffness (3 cases) due to rotator cuff disease ; acquired "surgical" stiffness, (10 cases). The capsular release was performed, at the anterior rim of the glenoid fossa, purely anterior or anterior and inferior, followed by gentle manipulation. If external rotation was not improved the coraco-humeral ligament was detached from its coracoid attachment. Additional procedures were performed:acromioplasty (5 cases), bursectomy (3 cases), SLAP lesion debridement (1 case). Only 2 out 13 primary shoulders required an additional procedure. RESULTS: 1-There were no intra-operative complications (vascular or neural). 2-Range of Motion: the average gain under anesthesia was: abduction: 72 degrees, external rotation: 34 degrees, forward flexion: 86 degrees. Final result was obtained with a mean duration of seven months. There was no difference according to the aetiology. Gain was more important in the primary group (9.69 to 34.9 vs 15.8 to 30.6). 3-Subjective results were better in the primary group. 4-Objective results demonstrated an absolute Constant's score of 70.3, that is to say 83.4 per cent of the contralateral supposed healthy shoulder. There were 3 excellent, 5 very good, 7 good, but 11 fair or poor results. The relative Constant's score was 91 per cent in the primary group and only 76 per cent in the acquired group. The difference was due to the pain and strength which were greatly improved in the primary group. DISCUSSION: Arthroscopic release of shoulder contracture is feasible, safe and effective. For primary frozen shoulder, there is usually spontaneous recovery. Indications for surgery are very few. There is no evidence that arthroscopic release shortens spontaneous evolution. Therefore, we propose it in very selected cases of dramatically limited motion. One year of evolution is an acceptable time. For bipolar stiffnesses, arthroscopy allows one to recognize the exact cause of the stiffness and to treat it, especially the subacromial pathology. In this occurrence, buroscopy must be performed and cuff pathology treated. For acquired surgical stiffnesses, gain of motion is significant. Subjective and objective results are less satisfactory than those of primary frozen shoulder, due to persistance of pain and lack of strength. The alternative is open release, but arthroscopic release has less morbidity. It can be proposed early as soon as capsular tissue has healed (for instance 6 months).     

The role of anteromedial foraminotomy and the uncovertebral joints in the stability of the cervical spine. A biomechanical study

STUDY DESIGN: The biomechanical role of the cervical uncovertebral joint was investigated using human cadaveric spines. Sequential resection of cervical uncovertebral joints, including clinical anteromedial foraminotomy, was conducted, followed by biomechanical testing after each stage of resection. OBJECTIVES: To clarify the biomechanical role of uncovertebral joints and clinical anteromedial foraminotomy in the cervical spine and their effects on interbody bone graft stability. SUMMARY OF BACKGROUND DATA: Although the biomechanical role of the cervical uncovertebral joints has been considered to be that of a guiding mechanism in flexion and extension and a limiting mechanism in posterior translation and lateral bending, there have been no studies quantifying this role. According to results in quantitative anatomic studies, anatomic variations exist in uncovertebral joints, depending on the vertebral level, articular angulation, and relative height of the joints. METHODS: Fourteen human functional spinal units at C3-C4 and C6-C7 underwent sequential uncovertebral joint resection, with each stage of resection followed by biomechanical testing. The uncovertebral joint was divided anatomically into three parts on each side: the posterior foraminal part, the posterior half, and the anterior half. The loading modes included torsion, flexion, extension, and lateral bending. A simulated anterior bone graft construct was also tested after each uncovertebral joint resection procedure. RESULTS: Significant changes in stability were observed after sequential uncovertebral joint resection in all loading modes (P < 0.05). The biomechanical contribution of uncovertebral joints decreased in the following order: the posterior foraminal part, the posterior half, and the anterior half. Unilateral and bilateral foraminotomy most affected the stability of the functional spinal unit during extension, causing a 30% and 36% decrease in stiffness of the functional spinal unit, respectively. The effect was less in torsion and lateral bending. After sequential resection, there was a statistically significant difference between decreases in torsional stiffness at C3-C4 and C6-C7 (P < 0.05). The stiffness of the simulated bone graft construct decreased progressively during flexion and lateral bending after each foraminotomy (P < 0.05). Increased bone graft height of 79% returned stability to the preforaminotomy level. CONCLUSIONS: This is the first study to quantitate the biomechanical role of uncovertebral joints in cervical segmental stability and the effect at each intervertebral level. The effect differs because of anatomic variations in uncovertebral joints. The major biomechanical function of uncovertebral joints includes the regulation of extension and lateral bending motion, followed by torsion, which is mainly provided by the posterior uncovertebral joints. This study highlights the clinical assessment of additional segmental instability attributed to destruction of the uncovertebral joints during surgical procedures or by neoplastic lesions.     

Transient osteoporosis of the hip in pregnancy

STUDY DESIGN: Fresh calf lumbar spines were used to perform flexibility tests in multiple loading directions to compare the stabilizing effects of anterior and posterior rigid instrumentations. OBJECTIVE: To compare the biomechanical flexibility of anterior and posterior instrumentation constructs using an unstable calf spine model. SUMMARY OF BACKGROUND DATA: Unstable burst fractures of the thoracolumbar spine can be managed anteriorly or posteriorly. Controversy persists, however, on the merit of anterior fixation versus that of posterior fixation in terms of how much stability can be achieved. METHODS: Fifteen fresh calf spines (L2-L5) were loaded with pure unconstrained moments in flexion, extension, axial rotation, and lateral bending directions. After removal of L3-L4 disc and endplates to create an 1.5-cm anterior and middle column defect, testing was performed on five specimens after anterior Kaneda rod fixation, anterior University Plate fixation, or posterior ISOLA pedicle screw fixation (AcroMed, Cleveland, OH). Testing was repeated after inserting a polymethylmethacrylate block to stimulate an interbody anterior graft with instrumentation. RESULTS: All fixation devices provided a significant stabilizing effect in flexion and lateral bending. In extension, all constructs except ISOLA (AcroMed) without graft were stiffer than the intact specimen. In axial rotation with no graft, only the Kaneda device significantly reduced the flexibility from that of the intact specimen. The interbody graft provided additional rigidity to the ISOLA (AcroMed) instrumentation construct in flexion and extension and to the Kaneda construct in lateral bending. There was no significant effect of grafting in axial rotation. CONCLUSIONS: A short, transpedicular instrumentation, such as ISOLA (AcroMed), provided less rigid fixation in flexion and extension without the anterior structural graft. The Kaneda rod and University plate with grafting provided a significant stabilizing effect in all directions compared with the intact specimen. When no graft was inserted, the Kaneda device was more effective in preventing axial rotation than the other devices. In lateral bending, the University plate provided more rigid fixation than the Kaneda device without grafting.     

Placental restriction alters adrenal medullary development in the midgestation sheep fetus

This is a retrospective study of 10 patients with combined cruciate ligament and posterolateral instability who underwent surgical reconstruction between 1991 and 1994. All knees had at least 20 degrees increased external rotation at 30 degrees of knee flexion and from 1+ to 3+ varus instability. Five knees with posterior cruciate ligament ruptures had at least a 2+ Lachman test result. (One knee had both anterior and posterior cruciate ligament injuries). In all cases the lateral collateral ligament was reconstructed with a bone-patellar tendon-bone allograft secured with interference screws. Fixation tunnels were placed in the fibular head and at the isometric point on the femur. The cruciate ligaments were reconstructed with autograft or allograft material. The average follow-up was 28 months. Excessive external rotation at 30 degrees of flexion was corrected in all but one knee. Six patients had no varus laxity, and four patients had 1+ varus laxity at 30 degrees of flexion. The posterior drawer test result decreased, on average, to 1+, and the Lachman test result decreased to between 0 and 1+. The average Tegner score was 4.6, with five patients returning to their preinjury level of activity and four returning to one level lower. These results indicate that this is a promising new procedure for patients with instability resulting from lateral ligament injuries of the knee.