AM bundle controls the anterior-posterior and rotational stability to a greater extent than the PL bundle - a cadaver study

BACKGROUND

The purpose of this study was to evaluate the influence of both bundles of the anterior cruciate ligament (ACL) on knee stability, anterior-posterior translation (APT) and internal (IR) and external (ER) rotation in cadaveric knees using a computer navigation system.

METHODS

The APT, IR, and ER of the knees were recorded in the intact condition, the anterolateral bundle (AM) or the posterolateral bundle (PL) deficit condition and in the ACL-deficient condition. The KT-1000 arthrometer was used for APT evaluation. The measurement of rotational movements was done using a rollimeter. All tests were performed at 30°, 60° and 90° of flexion.

RESULTS

At 30° of flexion: In the intact knee APT was 5.8mm, IR 12.1°, ER 10.1°. After the AM was cut, the APT increased to 9.1mm, IR to 13.9° and ER to 12.6°. After the PL was cut, the APT was 6.4mm, IR 13.1° and ER 10.6°. After the AM and PL were cut, the APT was 10.8mm, IR 15.7° and the ER was 12.9° on average.

CONCLUSIONS

The AM has a greater impact on the APT than the PL in all knee joint flexion angles. The PL does not resist the rotational stability more than the AM. The rotational stability is better controlled by both bundles of ACL as compared to one bundle of the ACL.

CLINICAL RELEVANCE

This study acknowledges the fact that the both bundles of the ACL are importants for AP and rotational stability of the knee joint.

[Computer-assisted kinematic 2D and 3D navigation in medial opening-wedge high-tibial valgus osteotomy]

PURPOSE OF THE STUDY

The aim of the study was to assess the accuracy of axis deformity correction achieved by high-tibial valgus osteotomy either without or with a computer-assisted kinematic navigation system, on the basis of comparing the planned and the achieved frontal axis of the leg. Comparisons of mechanical axis deviation were made using both pre- and post-operative measurements with the planning software and intra-operative measurements with the navigation system before and after osteotomy. In addition, the aim was to test the hypothesis that the use of 3D navigation, as compared with 2D navigation, would help reduce changes in the tibial plateau slope

MATERIAL AND METHODS

In the period 2008-2011, high-tibial osteotomy was performed in 68 patients. Twenty-one patients (group 1) underwent osteotomy without the use of navigation and 47 patients (group 2) had osteotomy with a computer-assisted navigation system (32 with 2D navigation and 15 with 3D navigation). Using the planning software, the mechanical leg axis before and after surgery and the anatomical dorsal proximal tibial angle in the sagittal plane were assessed. Medial openingwedge high-tibial valgus osteotomy was carried out in all patients. When using 2D navigation, the mechanical leg axis was measured intra-operatively before osteotomy and then after osteosynthesis which included a simulated axial load of the heel. When using 3D navigation, the procedure was identical and furthermore involved a measurement of the tibial plateau slope obtained with an additional probe in the proximal fragment. The results were characterised using descriptive statistics and their significance was evaluated using the Mann-Whitney U test and Wilcoxon's test, with the level of significance set at p < 0.05.

RESULTS

In group 1, osteotomy resulted in good correction of the mechanical axis in nine patients (43%), inadequate correction in nine (43%) and overcorrection and three (14%) patients. In group 2 with the use of navigation, accurate correction of the mechanical leg axis was achieved in 24 patients (51%), undercorrection was recorded in 21 (45%) and overcorrection in two (4%) patients. The difference in outcomes between the two groups was not statistically significant (p = 0.73). The average correction of the mechanical axis based on comparing measurements on pre- and post-operative radiographs was 9.1 degrees (range, 5-27 degrees); the average correction of the axis visualised intra-operatively was 8.7 degrees (range, 4-27 degrees). The difference was not significant (p = 0.1615) and confirmed our hypothesis that the accuracy of measuring the mechanical axis was not influenced by the method used. The average change in the dorsal slope of the tibial plateau following osteotomy without navigation was 0.9 degrees (range, -8.9 to 9.0 degrees) and that after osteotomy with intra-operative visualisation of the proximal tibial slope was 0.3 degrees (range, -4 to 4 degrees). This difference was not statistically significant (p = 0.813).

DISCUSSION

A good clinical outcome of high-tibial valgus osteotomy depends on achieving accurate correction of the mechanical leg axis with partial load transfer to the lateral compartment of the knee.

CONCLUSIONS

Although the number of cases with good correction was slightly higher in the patients undergoing osteotomy with navigation, the difference was not significant. Intra-operative visualisation of the mechanical axis proved sufficiently accurate on comparison with the pre-operative planning based on weight-bearing radiography of the leg. A simulated axial load of the heel included in the kinematic navigation system does not sufficiently correspond to normal weight-bearing and therefore an undercorrection of the deformity might occur. Using 3D navigation had no marked effect on a change in the slope of the tibial plateau.

Does the posterolateral bundle influence rotational movement more than the anteromedial bundle in anterior cruciate ligament reconstruction?

The biomechanical function of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) remains controversial. Some studies report that the AM bundle stabilises the knee joint in anteroposterior (AP) translation and rotational movement (both internal and external) to the same extent as the PL bundle. Others conclude that the PL bundle is more important than the AM in controlling rotational movement.

The objective of this randomised cohort study involving 60 patients (39 men and 21 women) with a mean age of 32.9 years (18 to 53) was to evaluate the function of the AM and the PL bundles of the ACL in both AP and rotational movements of the knee joint after single-bundle and double-bundle ACL reconstruction using a computer navigation system. In the double-bundle group the patients were also randomised to have the AM or the PL bundle tensioned first, with knee laxity measured after each stage of reconstruction. All patients had isolated complete ACL tears, and the presence of a meniscal injury was the only supplementary pathology permitted for inclusion in the trial. The KT-1000 arthrometer was used to apply a constant load to evaluate the AP translation and the rolimeter was used to apply a constant rotational force. For the single-bundle group deviation was measured before and after ACL reconstruction. In the double-bundle group deviation was measured for the ACL-deficient, AM- or PL-reconstructed first conditions and for the total reconstruction.

We found that the AM bundle in the double-bundle group controlled rotation as much as the single-bundle technique, and to a greater extent than the PL bundle in the double-bundle technique. The double-bundle technique increases AP translation and rotational stability in internal rotation more than the single-bundle technique.

[The effect of releasing the medial stabilisers of the knee on the magnitude of correction in opening-wedge high-tibial valgus osteotomy. Anatomy study on cadavers]

PURPOSE OF THE STUDY

When a larger opening of high-tibial osteotomy is necessary to achieve good correction of the lower extremity axis, partial release of the attachments of the medial stabilisers of the knee may be required. The aim of the study was to ascertain, in cadaver specimens, the effect of loosening the medial knee stabilisers on the magnitude of correction in medial opening-wedge high-tibial valgus osteotomy.

MATERIAL AND METHODS

Thirty-eight knees obtained from cadavers of Caucasian race were dissected. Medial opening-wedge high-tibial valgus osteotomy was performed using a dynamic distractor, constructed by us, with a dynamometer to ensure constant force action. Using a kinematic navigation system, the lower leg axis was studied at opening-wedge osteotomy under constant forces of 100 N and 150 N. The change in its angulation was recorded after each step in releasing the medial stabilisers whose structures were gradually made loose, under constant action of the given force, in the following order: superficial portion of the medial collateral ligament, tendons of the gracilis, semitendinosus and sartorius muscles.

RESULTS

The results were statistically analysed using descriptive statistical methods and the two-sample paired t-test with the level of statistical significance set at p < 0.05. Loosening of the medial stabilisers one by one under a constant load led to a statistically significant change in alignment. The most significant change in angulation, both in clinical and statistical terms, was that of 3.4° occurring after the superficial portion of the medial collateral ligament was made loose under a constant force of 100 N applied to osteotomy. Thus, this loosening contributed by 62% to an overall change of 5.5° in the lower extremity mechanical axis, as compared with the condition not allowing for loosening of the stabilisers. Under a load of 150 N applied to osteotomy, loosening of the medial collateral ligament resulted in a change by 4.1°, which accounted for 56% of an overall change of 7.3° that occurred after all stabilisers were released. On distraction of the osteotomy using a higher force, an increase in a stabilising effect of the pes anserinus was apparent.

DISCUSSION

The evolution of angle-stable implants has advanced options for reliable fixation of high-tibial corrective osteotomy which involves cutting out a wedge and forcing it open on the medial side. These implants provide stable fixation even when a large correction of the limb mechanical axis is required, and allow for rehabilitation with early weight-bearing. As with a large correction the force needed to make the wedge open is increasing, it is necessary to consider loosening of the medial stabilisers of the knee. According to our knowledge, no study on the effect of individual medial stabilising structures of the knee on the force required to open high-tibial osteotomy with the wedge opened medially has been published.

CONCLUSIONS

The process of correcting lower extremity alignment by high-tibial opening-wedge valgus osteotomy brings about an increase in tension of the stabilisers on the concave side of the deformity. Our results show an important role of releasing the superficial portion of the medial collateral ligament in the reduction of forces necessary to correct a deformity.

[Posterior extensile approach to release a post-traumatic stiffness of the elbow]

PURPOSE OF THE STUDY

Restriction of joint motion is a frequent complication in the treatment of elbow injury. Grade 4 elbow stiffness up to its ankylosis is a strong limiting factor in the patient's daily activities. The surgical release of a stiff elbow has been a rare procedure. It can be done using either isolated or combined approaches. The aim of the study is to present our experience with and the results of elbow arthrolysis using a posterior extensile approach to the joint.

MATERIAL AND METHODS

Seven patients aged between 17 and 38 years with post-traumatic post-operative ankylosis, or grade 4 elbow stiffness were operated on. The average range of motion before surgery was 12.9° (range, 0° - 20°). The average interval between primary injury and arthrolysis was 21 months (range, 8 - 70 months). Clinical assessment before and after surgery was based on the Mayo Elbow Performance Score (MEPS). The average follow-up was 26 months (12 - 47). Arthrolysis was completed by application of an external fixator in four patients, by interposition arthroplasty in two patients, ulnar nerve transposition in five patients and radial head replacement in one patient. RESULTS The average MEPS score increased from 45.0 points (range, 30 - 65 points) to 87.9 points (range, 75 - 100 points). The average range of motion at the final follow-up was 99.3° (range, 65° - 135°). Most patients reported pain relief. There was no iatrogenic instability following surgery. Improvement was most marked in relation to joint function, as demonstrated by increase from an average score of 6.4 points (range, 0 - 15 points) before surgery to 24.3 points (range, 20 - 25 points) after surgery in the MEPS.

DISCUSSION

Surgical treatment of an ankylosed elbow is not a common procedure in the majority of hospitals. The use of a posterior extensile approach, which preserves the extensor mechanism, to release the elbow joint has been reported only occasionally in the international literature. The results, however, seem to be good. On the other hand, removal of the olecranon is associated with a high complication rate. Operative release of the elbow with total joint replacement is an extreme option. CONCLUSIONS In grade 4 stiff elbow release, the posterior extensile approach to the elbow joint as described here allows us to have a good view of all articular compartments. It maintains continuity of the extensor apparatus of the elbow, which is the essential requirement for effective post-operative rehabilitation and therefore its great advantage. This approach is not associated with serious complications.

[Reduction of radiation exposure by the use of fluoroscopic guidance in transpedicular instrumentation]

PURPOSE OF THE STUDY

The variability in width, height, and orientation of spinal pedicles makes pedicle screw insertion a delicate operation. Fluoroscopic guidance often exposes the patient and especially surgeons to relatively high doses of ionising radiation. The use of pulsed fluoroscopy is safer, as compared to continuous fluoroscopy, because of reduced radiation exposure. There are increasing numbers of literature reports regarding the high doses of radiation to which orthopaedic and spine surgeons are exposed during surgical procedures. Spine surgery can be associated with significant radiation exposure to the surgical staff. The purpose of this prospective study was to compare a computer-assisted navigation with a conventional procedure in order to assess if it is possible to reduce radiation exposure while preserving the accuracy of screw placement.

MATERIAL AND METHODS

The first "conventional" group consisted of 30 patients, with an average of 1.9 segments of the lumbar spine stabilised. Screws were inserted transpedicularly under image intensifier guidance. In the second "navigated" group of 30 patients, stabilisation of 1,8 segments was performed on average. A CT-free fluoroscopic 2D spinal navigation system (VectorVision, Brain LAB, Germany) was used intra-operatively. It combines image-guided surgery with C-arm fluoroscopy. For each surgery (navigated or not), the duration of irradiation was recorded. The irradiation duration was collected from the X-ray image intensifier. In both groups the screw positioning accuracy was controlled intra-operatively according to Learch's, Acikbas's, and Whitecloud's methods from AP and lateral images and by meticulous pedicle palpation.

RESULTS

The irradiation duration calculated to one vertebra (two screws) was significantly shorter in the second (navigated) group (3.4 s) than in the first (conventional) group (14.4 s). The mean duration of data registration was 6.0 minutes (range, 3 to 11 minutes). The mean ratio according to Acikbas's calculation method was 43.2 % (range, 32 % to 74 %) in the first (conventional) group and 44.1 % (range, 35 % to 76 %) in the second (navigated) group.

DISCUSSION

During a conventional surgical procedure many X-ray images are made to control the accuracy of screw insertion. If the trajectory is not satisfying, it must be corrected or the pedicle is drilled again, always with a new fluoroscopic control. The process is repeated until satisfactory orientation is achieved. This is the explanation for a much longer duration of irradiation in conventional procedures. Navigation facilitates the surgical act, enabling us to acquire the right position of all screws, with only an AP image and a lateral image at the beginning of instrumentation for data registration; prolongation of the operative time is irrelevant.

CONCLUSIONS

Navigation allows us to keep the same accuracy of pedicle screw placement while reducing radiation exposure of the surgeons and operating room staff by about one quarter. In multiple-level vertebral instrumentations this reduction is more pronounced. In centres where many procedures involving spine instrumentation are done every day, the "saved" exposure time can amount to hours.

[Injection of anaesthetic-corticosteroid to relieve sacroiliac joint pain after lumbar stabilisation]

PURPOSE OF THE STUDY

Both the range of motion and load transfer of the sacroiliac (SI) joint improve considerably after lumbar spine surgery. When, following surgery, SI joint pain develops in spite of appropriate physical therapy, injection of an anaesthetic with added corticosteroid into the SI joint is a first choice treatment. The aim of this presentation is to provide information on our experience with this therapy.

MATERIAL AND METHODS

Thirty-four patients after lumbar spine fusion reported lumbalgia different form pain before surgery. In 14 (41%) of them, pain in one of the SI joints was diagnosed as the cause. This group included 12 women and two men at an average age of 56 (range, 47 to 68) years. Ten patients underwent lumbosacral fixation and four had segmental ("floating") lumbar spine fusion. All patients experienced lumbalgia at more than 3 months following surgery, at 8 months on the average (range, 4 to 12 months). None of them had SI joint pain before surgery. The diagnosis was based on specific manoeuvres on physical examination of the joint. Each patient was given an injection of 20 mg (0.5 ml) Methylprednisolone (Depo-Medrol®, Pfizer, Puurs, Belgium) and 4.5 ml 1% Mesocain (Zentiva, Praha, CR).They were inquired as to pain relief 24 h later and then at 1, 3 and 6 months after injection. Subjective feelings were assessed by a visual analogue scale (VAS). The results were analysed using descriptive statistics.

RESULTS

All patients reported pain relief within 24 h of injection, but not its complete resolution. The average VAS score before and after the blockage of the SI joint was 9.1 points (8-10) and 4.8 points (2-7), respectively; this implies improvement by an average of 4.3 points (1-6), i.e., approximately by 47.3% (12.5-62.5). The duration of effects varied greatly from patient to patient. The average interval between injection and pain recurrence lasted for 5 weeks (1-28). Most frequently, relief was experienced for 2 weeks, or for 6.8 weeks with the standard deviation included. DISCUSSION Sacroiliac joint dysfunction is a very frequent cause of lumbalgia, particularly after lumbar spine surgery. Physical therapy may not always be effective. SI joint arthrodesis is indicated only in rare cases. One of the few possibilities of pain relief involves intra-articular injection of an anaesthetic with corticosteroid for booster effect. The treatment of SI joint blockage after spinal fusion has recently been dealt with in three reports in the international literature; their conclusions are in accordance with the results of this study.

CONCLUSIONS

Lumbar spine stabilisation surgery may result in overloading the SI joints as the "adjacent segments". An intra-articular injection of anaesthetic can be considered a reliable method for ascertaining the SI joint as the source of a patient's problems. However, even with corticosteroid added, pain relief is not usually long-lasting.

[Transhumeral head plasty and massive osteocartilaginous allograft transplantation for the management of large hill-sachs lesions]

PURPOSE OF THE STUDY

The aim of this presentation is to inform the medical community about causal therapy (transhumeral head plasty or massive osteochondral allograft transplantation) for large Hill-Sachs lesions which frequently cause failure of anterior stabilisation following ventral shoulder dislocations.

MATERIAL

Seven men with an average age of 26 years (19 to 33 years) undergoing surgery in 2006 and 2007 were evaluated. The minimum follow-up was 18 months (41 to 18 months). Impressions on more than 30 % of the articular surface, or those whose critical size was larger than one-eighth of the humeral diameter (on CT scan) were taken as indications for surgery. Four patients had had previous surgery for anterior instability and three had a primary procedure. Four men underwent acute surgery and three had elective operations.Trans- humeral head plasty was used in five and massive osteochondral allograft in two patients.

METHODS

In the patients with large lesions in the anterior aspect of the shoulder joint, transhumeral head plasty involving repair of the ventral structures from the anterior approach was indicatedúúú in those with an isolated posterior bony defect, a massive osteochondral allograft was transplanted through the posterior approach. The Constant-Murley score was used to assess clinical status before (not in acute conditions) and after surgery.

RESULTS

All patients reported improved clinical status. The average Constant-Murley score at final follow-up was 95.9 points (83-100 points). In the patients not having an acute procedure in whom pre-operative Constant-Murley scores were obtained, the average improvement was by 22.7 points (8 - 37 points). No general surgical complications were recorded. All patients reported subjective satisfaction and willingness to undergo surgery under the same conditions again.

DISCUSSION

A Hill-Sachs lesion is a frequent injury to the humeral head resulting from anterior shoulder dislocation. To distinguish between major and minor defects in terms of clinical significance is essential for the choice of appropriate shoulder treatment. Up to now large lesions have mostly been managed by non-causal techniques affecting shoulder biomechanics. Transhumeral head plasty or transplantation of a massive osteochondral allograft, on the other hand, offers a causal treatment. However, these two methods have rarely been mentioned in the international literature, and usually only as case reports.

CONCLUSIONS

Transhumeral head plasty and transplantation of a massive osteochondral allograft offer a causal therapy for the management of Hill-Sachs lesions that does not alter shoulder biomechanics. They are not associated with a higher percentage of post-operative complications. Neither technique is more demanding than non-causal procedures. Operations carried out as primary and not as "salvage" procedures restored the function of the shoulder joint to normal. After secondary surgery, occasional shoulder pain may persist as well as its restricted range of motion.