Transforaminal lumbar interbody fusion vs. posterolateral instrumented fusion: cost-utility evaluation along side an RCT with a 2-year follow-up.

PURPOSE: Long-lasting low back pain is an increasing problem, and for some patients surgery is the final option for improvement. Several techniques for spinal fusion are available and the optimal technique remains uncertain. The objective of this study was to assess the cost-effectiveness and cost-utility of transforaminal lumbar interbody fusion (TLIF) compared to posterolateral instrumented fusion (PLF) from the societal perspective. METHODS: 100 Patients were randomized to TLIF or PLF (51/49) and followed for 2 years. Cost data were acquired from national registers, and outcomes were measured using the Oswestry Disability Index and SF-6D questionnaires. Conventional cost-effectiveness methodology was employed to estimate net benefit and to illustrate cost-effectiveness acceptability curves. The statistical analysis was based on means and bootstrapped confidence intervals. RESULTS: Results showed no statistically significant difference in either cost or effects although a tendency for the TLIF regimen being more costly on bed days (2,554) and production loss (1,915) was observed. The probability that TLIF would be cost-effective did not exceed 30 % for any threshold of willingness to pay per quality-adjusted life year. Sensitivity analysis was conducted and supported the statistical model for handling of missing data. CONCLUSION: TLIF does not seem to be a relevant alternative to PLF from a socioeconomic, societal point of view.

Humeral head size in shoulder arthroplasty: a kinematic study.

Changes in kinematics after hemiarthroplasty of the glenohumeral joint were investigated in nine cadaveric specimens. During experiments the influence of the humeral head size on glenohumeral kinematics was evaluated. A modular prosthesis with five different head sizes and press-fit stems was used. Three-dimensional kinematic measurements during abduction and adduction from 0 degree to 70 degrees showed increased external rotation with increasing head size. Small prosthetic heads translated inferiorly and large prosthetic heads superiorly compared with the intact humeral head. During forced anterior and posterior translation the mobility is restricted with increasing head size. This study found that when a press-fit prosthesis is used, it takes 1.25 times the volume of the intact humeral head to reconstruct the kinematics of the glenohumeral joint.

Lateral collateral ligament of the elbow joint: anatomy and kinematics.

The structure and kinematics of the lateral collateral ligament of the elbow joint were investigated in 10 cadaveric specimens. The lateral collateral ligament was observed to be a distinct part of the lateral collateral ligament complex. It contains posterior fibers that pass through the annular ligament and insert on the ulna. Three-dimensional kinematic measurements in different forearm rotations showed that joint puncture induced a 1 degree joint laxity significant in forced varus from 30 degrees to 80 degrees of flexion and in forced external rotation from 30 degrees to 120 degrees of flexion. Division of the posterolateral capsule caused no further laxity. Cutting the lateral collateral ligament induced a maximum laxity of 11.8 degrees at 110 degrees of flexion in forced varus and a maximum laxity of 20.6 degrees at 110 degrees of flexion in forced external rotation. The corresponding maximal posterior radial head translation was observed at 80 degrees to 100 degrees of flexion and was 5.7 mm in forced varus and 8.1 mm in forced external rotation. This study suggests the lateral collateral ligament to be an important stabilizer of the humeroulnar joint and the radial head in forced varus and external rotation. The humeroulnar stability is independent of forearm rotation.

Shoulder instability caused by rotator cuff lesions. An in vitro study.

Although many clinical and experimental studies have been published on shoulder instability, little is known about the relationship between degenerative changes of the cranial part of the rotator cuff and shoulder instability. The fact that some cuff lesions cause few symptoms and do not progress, while others are not only incapacitating but also progress to massive ruptures and cuff arthropathy, is still not well understood. In this study the motion patterns of the intact joint, and changes induced by a division of the supraspinatus tendon alone or of the supra- and infraspinatus tendons, were investigated in cadaver specimens. The results demonstrate that a one tendon lesion does not influence the motion pattern, whereas a two tendon lesion induces significant changes compatible with instability of the glenohumeral joint.

Elbow joint instability: A kinematic model.

The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the elbow joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant elbow joint instability in valgus and varus stress and in forced external and internal rotation. The mean maximum laxity in valgus stress and forced external rotation were 5.7° and 13.2°. The forearms of the elbow joint specimens were transfixed in maximum pronation. During valgus and varus stress the corresponding spontaneous ulnar rotation of the specimens was recorded. The reproducibility of the instability pattern suggests that this model is suitable for evaluating stabilizing procedures aimed at correction of elbow joint instability before these procedures are introduced into patient care.

Glenohumeral movement patterns after puncture of the joint capsule: An experimental study.

In on experimental series comprising 22 shoulder specimens obtained at autopsy, we investigated the influence of an intact capsule on glenohumeral stability. Puncture of the capsule resulted in significant glenohumeral translation in unloaded and loaded specimens during shoulder abduction. A maximum of 16.6 mm of distal translation was observed at 20° of abduction. Concomitant with this translation the humerus spontaneously rotated externally, with a maximum rotation of 15.8° at 50° of abduction. After venting the capsule, anterior and posterior translation and external rotation were increased significantly. Maximum total increase in anteroposterior translation was 14 mm at 30° of abduction. The external rotation was increased up to 7.1° at 40° of abduction. These findings indicate that studies evaluating glenohumeral instability are compromised unless the translations resulting from capsular venting ore corrected. Evaluation of shoulder stability should be performed before violation of the intraarticular pressure mechanisms.

Conservative treatment for acute rupture of the Achilles tendon.

Sixty-six patients with acute ruptures of the Achilles tendon were treated by immobilisation in a plaster cast for 12 weeks. Fifty-seven were followed up for a mean time of 70 months. Four re-ruptures occurred shortly after the initial treatment. Most patients had no or only slight complaints, three had moderate and one severe, problems. The activity level dropped slightly from 5.3 to 5.03 (Tegner score). The results are satisfactory with a low complication rate. The method is an alternative to operative repair, especially in patients declining operation and in those in whom operation or anaesthesia is contraindicated.

Instability of the hindfoot after lesion of the lateral ankle ligaments: investigations of the anterior drawer and adduction maneuvers in autopsy specimens.

The mobility patterns in the tibiotalocalcaneal joint complex with a solitary lesion of the anterior talofibular ligament (ATL) and a combined lesion of the ATL and calcaneofibular ligament (CFL) were studied in 22 human lower-extremity autopsy specimens mounted in a kinesiologic testing device. A solitary lesion of the ATL increased the anteroposterior (AP) laxity in the ankle joint in the entire range of flexion, with a maximum median of 3.1 mm in neutral flexion. Further cutting of the CFL increased AP laxity most obviously in dorsiflexion. A solitary lesion of the ATL resulted in a minor instability in adduction, whereas further lesion to the CFL increased adduction in the entire range of flexion, with a maximum median of 14.2 degrees in dorsiflexion. The anterior drawer maneuver can reveal a combined lesion of the ATL and CFL if performed with the tibiotalocalcaneal joint complex in dorsiflexion. Significant clinical instability in adduction will only take place when a combined lesion of the ATL and CFL is present.

Anterolateral instability in the anterior cruciate ligament deficient knee. A cadaver study.

Knee instability was evaluated in 13 normal osteoligamentous knee preparations after transection of the anterior cruciate ligament. Abduction-adduction rotation, coupled tibial translatory movement, and coupled tibial axial rotation were recorded continuously and simultaneously during flexion or extension while applying a well defined valgus directed moment and during extension while applying an anterior tibial force. As a result of the valgus-directed moment, an increase was found in abduction rotation, in coupled anterior tibial translation, and in coupled internal tibial axial rotation. Coupled rotatory and translatory instabilities were larger, and maximum instability was observed at a smaller knee angle during the extension movement than during the flexion movement. The pattern of the instability, excited as a result of the valgus moment, was different from the instability excited as a result of an anterior tibial force.

Distal humeral migration as a component of multidirectional shoulder instability. An anatomical study in autopsy specimens.

The object of the present study of autopsy specimens was to evaluate distal humeral migration during abduction allowed by sequential severance of capsular and ligamentous structures stabilizing the shoulder joint. A kinesiologic testing device continuously registered distal humeral migration, abduction angle, rotation, and flexion-extension. No distally directed force was applied to the humerus except the weight of the apparatus. Significant distal migration was recorded in the entire range of abduction (0 degrees -60 degrees) after solitary severance of the coracohumeral ligament as well as the proximal part of the anterior joint capsule. Further sectioning of the proximal part of the posterior capsule did not significantly increase distal humeral migration. Maximum distal migration (25 mm) was measured at 20 degrees of abduction. Applying an internal torque to the humerus significantly prevented distal migration as long as the posterior capsule was kept intact. Clinical testing for distal humeral migration should be performed with the shoulder joint at 20 degrees of abduction and neutral rotation. Furthermore, distal humeral migration can be significantly reduced by internal rotation of the humerus when the posterior joint capsule is intact.

Stabilizing effect of the tibiocalcaneal fascicle of the deltoid ligament on hindfoot joint movements: an experimental study.

The tibiocalcaneal fascicle of the deltoid ligament was studied in 10 lower leg amputation specimens to evaluate its stabilizing effect on movement in the tibiotalocalcaneal joint complex and the talocalcaneal joint complex. Cutting of the fascicle resulted in minor numerical increases in movement in all three planes in the tibiotalocalcaneal joint complex as well as in the talocalcaneal joint complex. The maximum median increase in the tibiotalocalcaneal joint complex was 6.1 degrees in abduction, whereas the maximum median increase in the talocalcaneal joint complex was 3.6 degrees in abduction. However, the percentage of increase in the total range of movement in a single plane was large for abduction-addition in both the tibiotalocalcaneal joint complex and the talocalcaneal joint complex, at 28% and 31%, respectively. The largest percentage of increase, 40%, was found in the total range of plantarflexion-dorsiflexion in the talocalcaneal joint complex. Our data suggest that the tibiocalcaneal fascicle is an important stabilizing structure of abduction, external rotation, and plantarflexion movements in the tibiotalocalcaneal joint complex, especially in the talocalcaneal joint complex.

Watson-Jones tenodesis for ankle instability. A mechanical analysis in amputation specimens.

The stabilizing effect of a modified Watson-Jones ankle tenodesis was studied in 10 lower extremity amputation specimens using a kinesiologic testing device. Cutting of the lateral ligaments caused maximal instability in adduction of the entire hindfoot joint complex, as well as of the talocalcaneal joint. The tenodesis restricted adduction and internal rotation when compared with the movement pattern with intact ligaments. Instability in external rotation persisted because the tenodesis did not restore the function of the calcaneofibular ligament. Our study confirms clinical observations that the Watson-Jones ankle tenodesis prevents abnormal inversion of the hindfoot, but does not restore hindfoot kinematics.

Dislocation of the elbow: an experimental study of the ligamentous injuries.

The stability of human cadaveric elbow specimens was investigated using an experimental apparatus. Posterior dislocation of the elbow could only be produced when a combined valgus and external rotatory torque was applied to the specimen. None of the elbows were dislocated during varus and internal rotatory torque or in the extreme positions. In ten elbow specimens with an experimentally produced posterior dislocation, simultaneous rupture of the anterior part of the medial collateral ligament and the annular ligament were the most frequent findings. A lateral collateral ligament tear was only seen in two cases. Posterior elbow dislocation seems to be due to a combined valgus and external rotatory stress to the semiflexed elbow, resulting in a bilateral ligamentous injury.

The stabilizing effect of the ligamentous structures in the sinus and canalis tarsi on movements in the hindfoot. An experimental study.

Three-plane kinesiology of hindfoot instability was studied after lesions to the ligamentous structures in the sinus and canalis tarsi in 20 amputation specimens. Neither a lesion of the cervical ligament nor of the interosseous talocalcaneal ligament resulted in an increase in the total range of movements above 2.6 degrees in any of the three planes. However, the percentage increase in the total range of movements after cutting of the ligaments was generally largest in the talocalcaneal joint compared to the increase in the total hindfoot joint complex. The largest percentage increase (43%) in the talocalcaneal joint occurred at dorsiflexion after cutting the interosseous talocalcaneal ligament. The demonstrated minor instability after experimental lesions of the ligamentous structures in the sinus and canalis tarsi may have a clinical identity in the sinus tarsi syndrome. Patients with that syndrome rarely present an objective hindfoot instability, although a major complaint is a feeling of hindfoot instability.

Effect of the calcaneofibular ligament on hindfoot rotation in amputation specimens.

A kinesiologic study of the range of rotation in the hindfoot after cutting of the calcaneofibular ligament was performed in amputation specimens. Cutting of the calcaneofibular ligament results in a significant increment in the external rotation of the tibial-talocalcaneal joint complex and the talocalcaneal joint, maximum 5.4 degrees and 2.9 degrees, respectively. The total range of rotation in the tibial-talocalcaneal joint complex and the talocalcaneal joint increased 32 and 20 per cent, respectively. The calcaneofibular ligament is an important structure in the rotatory stabilization of the hindfoot.

Posterior instability of the knee joint. An experimental study.

We investigated the importance of the posterior cruciate ligament (PCL) and the medial and lateral compartmental structures for translatory and simultaneous axial rotatory instability in 25 osteoligamentous knee preparations. Instability was registered continuously from 0 degree to 90 degrees of flexion with application of a constant force to the tibia. Isolated transection of the PCL increased the posterior tibial displacement with flexion to a maximum of 10 mm at 90 degrees of flexion; when combined lesions to the lateral structures were included, the popliteal tendon (PT) in particular turned out to have a major secondary stabilizing function. The posterior tibial displacement in flexion was doubled when all lateral structures were included in the lesions. Transection of the PCL and all the medial structures led to a notable increment in posterior displacement increasing with flexion. Major increments in simultaneous tibial rotation were recorded only after combined lesions to either medial or lateral structures. A reverse pivot shift was provoked after combined lateral lesions when the PT was included. Even an anteromedial subluxation was released after lesions to the medial structures. Regardless of the type of lesion, the specimens remained stable concerning anterior-posterior displacement in extension. No changes in the anterior tibial displacement were observed.

The static stabilizing function of the popliteal tendon in the knee. An experimental study.

We investigated the importance of the anterior cruciate ligament (ACL), its two components (the AMP and PLP), and the lateral compartment ligaments with special attention to the popliteal tendon (PT) in relation to valgus-varus, axial rotation, and anterior-posterior instability. Mobility patterns were drawn from 15 osteoligamentous knee preparations after successive transection of the structures. Even when combined lesion involved the lateral collateral ligament (LCL), the PT, and the posterolateral capsule (PLC), anterior tibial displacement was not effected until the ACL was cut. The lateral structures acted as secondary restraints to anterior displacement, and prevented simultaneous anterolateral rotation during application of the anterior force. LCL and PLC transection affected varus stability in full extension, and instability improved on additional section of the PT, even if the ACL remained intact. Maximum instability after combined lateral lesion occurred at 40 degrees of flexion, whether the ACL was transected or not. Further flexion caused a rapid decrease of instability. The PT was shown to effectively restrain varus instability from 0 to 90 degrees of flexion. It was experimentally established with regard to axial rotation that marked posterolateral instability was impossible with an intact PT. Maximum instability was recorded at 30 degrees of flexion after combined lesion to the lateral structures. Even in the extension, considerable posterolateral instability was observed. The restraining effect of the PLC was prominent in extension.

Instability of knees with ligament lesions. Cadaver studies of the anterior cruciate ligament.

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact. Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70-80 degrees, a sudden reduction was observed.