Tibiale Press-fit-Fixierungen von Beugesehnen zur Rekonstruktion des vorderen Kreuzbandes

Background

Press-fit fixation of hamstring tendon autografts for anterior cruciate ligament reconstruction is an interesting technique because no hardware is necessary. This study compares the biomechanical properties of press-fit fixations to an interference screw fixation.

Methods

Twenty-eight human cadaveric knees were used for hamstring tendon explantation. An additional bone block was harvested from the tibia. We used 28 porcine femora for graft fixation. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclic loading were investigated.

Results

The maximum load to failure was 970±83?N for the press-fit tape fixation (T), 572±151?N for the bone bridge fixation (TS), 544±109?N for the interference screw fixation (I), 402±77?N for the press-fit suture fixation (S) and 290±74?N for the bone block fixation technique (F). The T fixation had a significantly better maximum load to failure compared to all other techniques (p<0.001).

Conclusion

This study demonstrates that a tibial press-fit technique which uses an additional bone block has better maximum load to failure results compared to a simple interference screw fixation.     

„Ligament bracing“ – die augmentierte Kreuzbandnaht

Background

In the context of acute knee dislocations, suture repair of ruptured cruciate ligaments leads to good clinical results in 80% of cases. Disadvantages are low primary stability and subsequently secondary elongation of the sutured ligaments. In the present study, we compared primary stability of suture repair, reinforced by different suture augments, to cruciate ligament reconstruction.

Objective

The concept of ligament bracing with transosseous suture repair of the cruciate ligaments and additional suture augmentation is biomechanically superior to cruciate ligament reconstruction.

Material and methods

A total of 42 porcine knee joints divided into seven groups were examined. The stability of four different suture/augmentation combinations were compared to cruciate ligament reconstruction with human hamstring tendons. The investigational setup consisted of testing 1000 cycles with 20 N to 154 N load in a.-p. translation and 60° flexion. Elongation and load to failure were measured.

Results

Neither reconstruction (3.13?±?1.65 mm; 362?±?51 N) nor augmented suture repair (1.89–2.5 mm; 464–624 N) achieved the primary stability of the intact cruciate ligament (0.63?±?0.34 mm, 1012?±?91 N). In comparison to ligament reconstruction, all four augmented suture repairs showed minor elongation in the cyclic test and a higher load to failure. The isolated suture repair showed poor results (6.79?±?4.86 mm, 177?±?73 N).

Conclusion

Augmented suture repair provides significantly higher stability compared with isolated suture repair and reconstruction with hamstring tendons. The concept of ligament bracing could be a promising future treatment option in acute knee dislocations. Clinical results remain to be seen.     

Biomechanische Untersuchung zur Refixation der Tuberkula an Frakturschulterendoprothesen

Background

Elderly patients suffering from complex, non-reconstructable fractures of the proximal humerus are commonly treated by primary implantation of a shoulder endoprosthesis. One of the most critical factors for success or failure of treatment is still the refixation of the tuberosities.

Method

Using sheep infraspinatus tendons with attached tuberosities three different suture materials were investigated. For 2 of the suture materials 4 tests were accomplished and 5 tests were carried out for the third suture material. A material testing machine was used to perform cyclic loading tests (20 mm/min, F_min = 50 N, F_max = 100 N, respectively after 50 cycles: F_max + 50 N until failure).

Results

The results showed large variations in the average maximum forces (152.4 N for suture 1, 219.9 N for suture 2 and 452.3 N for suture 3). All tests showed a high initial lengthening and caused incision-like defects in the bone or tendon and led to failure and high displacement of the tuberosities.

Conclusion

Due to these results suture materials have a limited usefulness for refixation of tuberosities as an increased risk of obstruction for bony consolidation can result.     

Biomechanical advantage of C1 pedicle screws over C1 lateral mass screws: a cadaveric study

Purpose

The established technique for posterior C1 screw placement is via the lateral mass. Use of C1 monocortical pedicle screws is an emerging technique which utilizes the bone of the posterior arch while avoiding the paravertebral venous plexus and the C2 nerve root. This study compared the relative biomechanical fixation strengths of C1 pedicle screws with C1 lateral mass screws.

Methods

Nine human C1 vertebrae were instrumented with one lateral mass screw and one pedicle screw. The specimens were subjected to sinusoidal, cyclic (0.5 Hz) fatigue loading. Peak compressive and tensile forces started from ±25 N and constantly increased by 0.05 N every cycle. Testing was stopped at 5 mm displacement. Cycles to failure, displacement, and initial and end stiffness were measured. Finally, CT scans were taken and the removal torque measured.

Results

The pedicle screw technique consistently and significantly outperformed the lateral mass technique in cycles to failure (1,083 ± 166 vs. 689 ± 240 cycles), initial stiffness (24.6 ± 3.9 vs. 19.9 ± 3.2 N/mm), end stiffness (16.6 ± 2.7 vs. 11.6 ± 3.6 N/mm) and removal torque (0.70 ± 0.78 vs. 0.13 ± 0.09 N m). Only 33 % of pedicle screws were loose after testing compared to 100 % of lateral mass screws.

Conclusions

C1 pedicle screws were able to withstand higher toggle forces than lateral mass screws while maintaining a higher stiffness throughout and after testing. From a biomechanical point of view, the clinical use of pedicle screws in C1 is a promising alternative to lateral mass screws.     

Implantatfreie tibiale Fixierung des hinteren Kreuzbandes

Background

A secure tibial press fit technique in posterior cruciate ligament reconstructions may be a relevant alternative to common techniques because no hardware is necessary. Up to the present point in time no biomechanical data exist for a tibial press fit posterior cruciate ligament (PCL) reconstruction. This study compares the biomechanical properties of hamstring and quadriceps tendon grafts using a press fit technique with those of an interference screw fixation.

Methods

Quadriceps and hamstring tendons of 20 human cadavers (age 49.2±18.5 years) were used. A press fit fixation with a knot in the semitendinosus tendon (K) and a quadriceps tendon bone block graft (Q) were compared to an interference screw fixation (I) in 27 porcine tibiae. In each group, nine constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated.

Results

The maximum load to failure was 518±157 N (387–650 N) for the K group, 558±119 N (466–650 N) for the I group and 620±102 N (541–699 N) for the Q group. The stiffness was 55±27 N/mm (18–89 N/mm) for the K group, 117±62 N/mm (69–165 N/mm) for the I group and 65±21 N/mm (49–82 N/mm) for the Q group. The stiffness of the I group was significantly larger (ANOVA on ranks, P=0.01). The elongation during cyclical loading was significantly larger for all groups from the 1st to the 5th cycle compared to the elongation in between the 5th and the 20th cycle (P<0.03).

Conclusion

All techniques exhibited larger elongation during initial loading. Load to failure and stiffness were significantly different between the fixations. The Q fixation showed equal biomechanical properties compared to a pure tendon fixation (I) with an interference screw. The results of group K were inferior. All three investigated fixation techniques exhibit comparable biomechanical properties. Preconditioning of the constructs is critical. Future randomized, clinical trials have to investigate the biological effectiveness of these fixation techniques.     

Impact of tendon suturing on the interference fixation strength of quadrupled hamstring tendon grafts

Introduction

Interference screw fixation of soft tissue grafts has been a widely used fixation technique for cruciate ligament reconstruction. Suturing of the graft construct prior to graft fixation has been proposed to increase fixation strength; however, the effect on mechanical properties has not been well characterized. The goal of this study was to determine whether uniform suturing of the tendon graft affects (1) ultimate fixation strength of the hamstring tendon graft and (2) motion of the tendon in the bone tunnel during cyclic loading when comparing sutured grafts vs. unsutured grafts.

Method

Eight pairs of matched mature porcine tibias (age <2 years) and eight paired fresh-frozen human quadrupled hamstring tendon grafts were used. One quadrupled graft from each pair was placed into one of two groups. In the group A a single cerclage suture 3 cm from the doubled end of the graft was placed to join the four tendon strands. In group B a heavy suture was used to tightly unite the four strands of tendon graft to provide a better grip for the interference screw during fixation. The grafts were placed in tibial bone tunnels that matched the graft’s diameter and fixed with an interference screw. The looped end of the graft and the attached tibia were rigidly fixed in a material testing machine. The graft constructs were subjected to 100 cycles of 20–250 N load, followed by a load-to-failure test. In addition, a motion analysis system was used during cyclic testing to better determine the amount of elongation at the graft–tunnel interface. Statistical analysis of the failure load and stiffness and the overall elongation following cyclical loading was performed using the Wilcoxon rank sum test. Level of significance was set at p < 0.05.

Results

Elongation at the tendon–bone interface during sub-maximal cyclic loading was 2.4 ± 1.4 mm (unsutured) vs. 2.0 ± 0.7 mm (sutured) (p > 0.05). Failure load of the grafts without sutures (634 ± 86 N) was significantly lower than with the sutures (837 ± 183 N). Ultimate stiffness of group A (283 ± 34 N/mm) was lower than that of group B (331 ± 51 N/mm); however, this was not statistically significant (p = 0.051).

Conclusion

This study confirms that suturing of the graft construct before interference screw fixation may increase ultimate failure load. However, an improvement of structural properties in response to cyclic loading with sub-maximal loads could not be confirmed. Clinicians using interference screw fixation may suture the graft to improve fixation strength; however, suturing does not appear to allow a more aggressive rehabilitation after surgery.     

“Horizontal butterfly” technique in repair of radial meniscus tears: A biomechanical study

Introduction

Radial meniscus tears are seen in young patients, especially with anterior cruciate ligament ruptures. Repair of complete radial meniscus tear is necessary for the meniscus functions. The most important factor for success of the meniscus repair is primary stability, but it is still unknown which technique is ideal repair technique.

Biomechanical consequences of a posterior root tear of the lateral meniscus: stabilizing effect of the meniscofemoral ligament

Purpose

The purpose of this study was to evaluate the effects of different types of lateral meniscus root tears in terms of tibiofemoral contact stress.

Methods

Ten porcine knees each underwent five different testing conditions with the menisci intact, a simulated lateral posterior root tear with and without cutting the meniscofemoral ligament and with an artificial tear of the posterior root of the medial meniscus. Biomechanical testing was performed at 30° of flexion with an axial load of 100 N. A pressure sensor (st Sensor Type S2042, Novel, Munich) was used to measure the tibiofemoral contact area and the tibiofemoral contact pressure. Data were analyzed to assess the differences in contact area and tibiofemoral peak contact pressure among the five meniscal conditions.

Results

There was no significant difference in mean contact pressure between the state with the menisci intact and an isolated posterior root tear of the lateral meniscus. In case of a root tear and a tear of the meniscofemoral ligament, the contact area decreased in comparison with the intact state of the menisci. After additional cutting of the meniscofemoral ligament, the tibiofemoral contact pressure was significantly higher in comparison with the intact state and the avulsion injury. In the medial compartment, joint compression forces were significantly increased in comparison with the intact state after cutting the posterior root of the medial meniscus (P < 0.05).

Conclusions

The consequence of a medial meniscus root tear is well known and was verified by this analysis. The results of the present study show that the biomechanical consequences of a lateral meniscus root tear depend on the state of the meniscofemoral ligament. An increase in tibiofemoral contact pressure is only to be expected in combined injuries of the meniscus root and the meniscofemoral ligaments.

Clinical relevance

Posterior lateral meniscus root tear might have a better prognosis in terms of the development of osteoarthritis when the meniscofemoral ligament is intact.     

Comparison of outside-in and inside-out technique for tibial fixation of a soft-tissue graft in ACL reconstruction using the Shim technique

Introduction

The aim of this study was to compare the biomechanical properties of tibial fixation of a free tendon graft in ACL reconstruction using the Shim, a new wedge-shaped implant, in an outside-in technique to fixation by the Shim used in an inside-out technique and fixation by interference screw in a porcine model.

Materials and methods

Porcine tibia and flexor tendons were used. In Group 1, the Shim was applied outside-in. In Group 2, the Shim was inserted inside-out. In the Group 3, an 8-mm interference screw was used. Ten specimens were tested in each group. Load-to-failure, elongation, stiffness and failure mode were recorded. Cyclic loading was performed between 5 and 250 N for 1,000 cycles, followed by a load to failure testing.

Results

Mean maximum load-to-failure was 629.53 N in Group 1,648.54 N in Group 2 and 749.53 N in Group 3. There was no significant difference between the groups. Stiffness varied between 127.34 N/mm in Group 1, 151.27 N/mm in Group 2 and 182.25 N/mm in Group 3. No significant differences were found between outside-in Shim and interference screw fixation. No significant difference was found for elongation among the three groups. The main failure mode was a rupture of the tendon in the IFS group and a slippage of either the implant or the tendon in both groups using the Shim.

Conclusions

As no statistically significant difference could be seen concerning load to failure, stiffness and elongation between the inside-out and the outside-in techniques, the Shim can be used for tibial fixation in an outside-in or inside-out technique depending on the preference of the surgeon. To prevent slippage of the graft a hybrid fixation should be considered.     

Suture bridge transosseous equivalent repair is stronger than transosseous tied braided-tape

Background

This study biomechanically compares two methods of supraspinatus repair: single row transosseous braided-tape (BT) and suture bridge transosseous equivalent (SBTE) with 2 medial anchors and 2 lateral anchors. The purpose is to test the hypothesis that BT provides superior or equal biomechanical strength compared to SBTE.

Biomechanical comparison of different fixation techniques for reconstruction of tibial avulsion fractures of the anterior cruciate ligament

Purpose

The most common fixation techniques for tibial avulsion fractures of the anterior cruciate ligament (ACL) described in the literature are screw and suture fixation. The fixation of these fractures with the TightRope® device might be an alternative. Up to now it has been commonly used in other injuries, such as acromioclavicular joint or syndesmosis ruptures. The purpose of this study was to evaluate the biomechanical properties of different fixation techniques for the reconstruction of tibial avulsion fractures.

Methods

Type III tibial avulsion fractures were simulated in 40 porcine knees. Each specimen was randomly assigned to one of four groups: (1) anterograde screw fixation, (2) suture fixation, (3) TightRope® fixation or (4) control group. The initial displacement, strength to failure and the failure mode were documented.

Results

The maximum load to failure was 1,345?±?155.5 N for the control group, 402.5?±?117.6 N for the TightRope® group, 367?±?115.8 N for the suture group and 311.7?±?120.3 N for the screw group. The maximum load to failure of the control group was significantly larger compared to all other groups. The initial dislocation was 0.28?±?0.09 mm for the control group, 0.55?±?0.26 mm for the TightRope® group, 0.84?±?0.15 mm for the screw group and 1.14?±?0.9 mm for the suture group. The initial dislocation was significantly larger for the suture group compared to the TightRope® and control groups.

Conclusions

The TightRope® fixation shows significantly lower initial displacement compared to the suture group. The TightRope® fixation might be an alternative for the repair of ACL tibial avulsion fractures that can be used arthroscopically.     

A novel suture anchor constructed of cortical bone for rotator cuff repair: a biomechanical study on sheep humerus specimens

Purpose

The aim of this study was to evaluate biomechanical properties of a new type of suture anchors constructed of human cortical allograft bone and compare it with the similar standard titanium screw anchor for rotator cuff tears in sheep humerus model.

Methods

Twenty-four paired sheep humeri were harvested from 12 male sheep aged 18 months. Specimens were divided into cortical bone anchor group and titanium screw anchor group. The anchors loaded with two sutures were placed at the footprint of infraspinatus tendon. Cyclic loading test was performed from 10 to 60 N at 1 Hz for 500 cycles and followed by a load-to-failure test at 33 mm/sec. A paired t-test was used to compare the biomechanical properties of the anchors of each type.

Results

No anchors failed during the cyclic phase, and the cortical bone anchors were all pulled out intact. The cyclic displacement of the cortical bone anchor was not significantly greater than that of the titanium screw anchor (P?>?0.05). Student’s t test showed no statistically significant difference between anchors in terms of failure load (cortical bone anchor: 304.74?±?64.46 N versus titanium screw anchor: 328.45?±?89.58 N; P?=?0.213), ultimate load (cortical bone anchor: 325.82?±?76.45 N versus titanium screw anchor: 345.61?±?83.56 N; P?=?0.183), yield load (cortical bone anchor: 273.78?±?44.75 N versus titanium screw anchor: 284.72?±?56.37 N; P?=?0.326) or stiffness (cortical bone anchor: 52.97?±?14.28 N/mm versus titanium screw anchor: 62.38?±?18.35 N/mm; P?=?0.112).

Conclusions

In vitro, this experimental study suggested no statistically significant difference in initial fixation stability between the new type anchor and titanium screw anchor at a chosen level of significance (P?<?0.05). The new type of suture anchor constructed of cortical bone provides comparable initial fixation strength to a similar metallic anchor for rotator cuff repair.

     

Suture anchor fixation strength in osteopenic versus non-osteopenic bone for rotator cuff repair

Introduction

Rotator cuff tears are increasing with age. Does osteopenic bone have an influence on the pullout strength of suture anchors?

Materials and methods

SPIRALOK 5.0 mm (DePuy Mitek), Super Revo 5 mm and UltraSorb (both ConMed Linvatec) suture anchors were tested in six osteopenic and six healthy human cadaveric humeri. Incremental cyclic loading was performed. The ultimate failure load, anchor displacement, and the mode of failure were recorded.

Results

In the non-osteopenic bone group, the absorbable SPIRALOK 5.0 mm achieved a significantly better pullout strength (274 N ± 29 N, mean ± SD) than the titanium anchor Super Revo 5 mm (188 N ± 34 N, mean ± SD), and the tilting anchor UltraSorb (192 N ± 34 N, mean ± SD). In the osteopenic bone group no significant difference in the pullout strength was found. The failure mechanisms, such as anchor pullout, rupture at eyelet, suture breakage and breakage of eyelet, varied between the anchors.

Conclusion

The present study demonstrates that, in osteopenic bone, absorbable suture anchors do not have lower pullout strengths than metal anchors. In normal bone, the bioabsorbable anchor in this study even outperformed the non-absorbable anchor.

     

Clinical and Morphologic Factors Associated with Suture Anchor Refixation of Labral Tears in the Hip

Background

The acetabular labrum is critical to hip function. Surgical options for treatment of a damaged labrum include removal, debridement, and refixation using suture anchors.

Questions/Purposes

The purpose of this study is to determine if certain patient demographic and osseous morphological factors result in increased labral damage requiring refixation.

Methods

Data was collected prospectively from a consecutive series of 334 procedures performed from August 2010 to June 2011 for femoroacetabular impingement. Demographic data, including age, sex, and race, was collected from patient charts. Three-dimensional (3D) CT scans were reviewed to retrieve alpha angles, acetabular version, femoral version, and lateral center edge angle on the symptomatic hip.

Results

In 238 (71.3%) of the procedures, the labrum required refixation using suture anchors with a mean of 2.74 anchors being used. Of males, 78.8% required suture anchors and 62.3% of females required suture anchors. Among procedures requiring suture anchors, significantly more suture anchors were used in males (2.92) than females (2.47). Regression analysis showed a positive association between alpha angle, acetabular retroversion at 1 and 2 o’clock, and the number of suture anchors used. The mean alpha angle in the cohort that required suture anchors (63.1°) was significantly greater than the cohort that did not (59.4°).

Conclusion

This study found femoral deformities to contribute more to labral damage than acetabular deformities and highlighted the importance of preoperative 3D CT scans. This study provides demographic and morphologic factors to review preoperatively to evaluate if extensive labral damage is present and if suture anchor refixation will be required.     

Biomechanical comparison of vertebral augmentation with silicone and PMMA cement and two filling grades

Purpose

Vertebral augmentation with PMMA is a widely applied treatment of vertebral osteoporotic compression fractures. Subsequent fractures are a common complication, possibly due to the relatively high stiffness of PMMA in comparison with bone. Silicone as an augmentation material has biomechanical properties closer to those of bone and might, therefore, be an alternative. The study aimed to investigate the biomechanical differences, especially stiffness, of vertebral bodies with two augmentation materials and two filling grades.

Methods

Forty intact human osteoporotic vertebrae (T10–L5) were studied. Wedge fractures were produced in a standardized manner. For treatment, PMMA and silicone at two filling grades (16 and 35 % vertebral body fill) were assigned to four groups. Each specimen received 5,000 load cycles with a high load range of 20–65 % of fracture force, and stiffness was measured. Additional low-load stiffness measurements (100–500 N) were performed for intact and augmented vertebrae and after cyclic loading.

Results

Low-load stiffness testing after cyclic loading normalized to intact vertebrae showed increased stiffness with 35 and 16 % PMMA (115 and 110 %) and reduced stiffness with 35 and 16 % silicone (87 and 82 %). After cyclic loading (high load range), the stiffness normalized to the untreated vertebrae was 361 and 304 % with 35 and 16 % PMMA, and 243 and 222 % with 35 and 16 % silicone augmentation. For both high and low load ranges, the augmentation material had a significant effect on the stiffness of the augmented vertebra, while the filling grade did not significantly affect stiffness.

Conclusions

This study for the first time directly compared the stiffness of silicone-augmented and PMMA-augmented vertebral bodies. Silicone may be a viable option in the treatment of osteoporotic fractures and it has the biomechanical potential to reduce the risk of secondary fractures.     

Parametric and cadaveric models of lumbar flexion instability and flexion restricting dynamic stabilization system

Purpose

Development of a dynamic stabilization system often involves costly and time-consuming design iterations, testing and computational modeling. The aims of this study were (1) develop a simple parametric model of lumbar flexion instability and use this model to identify the appropriate stiffness of a flexion restricting stabilization system (FRSS), and (2) in a cadaveric experiment, validate the predictive value of the parametric model.

Methods

Literature was surveyed for typical parameters of intact and destabilized spines: stiffness in the high flexibility zone (HFZ) and high stiffness zone, and size of the HFZ. These values were used to construct a bilinear parametric model of flexion kinematics of intact and destabilized lumbar spines. FRSS implantation was modeled by iteratively superimposing constant flexion stiffnesses onto the parametric model. Five cadaveric lumbar spines were tested intact; after L4–L5 destabilization (nucleotomy, midline decompression); and after FRSS implantation. Specimens were loaded in flexion/extension (8 Nm/6 Nm) with 400 N follower load to characterize kinematics for comparison with the parametric model.

Results

To accomplish the goal of reducing ROM to intact levels and increasing stiffness to approximately 50 % greater than intact levels, flexion stiffness contributed by the FRSS was determined to be 0.5 Nm/deg using the parametric model. In biomechanical testing, the FRSS restored ROM of the destabilized segment from 146 ± 13 to 105 ± 21 % of intact, and stiffness in the HFZ from 41 ± 7 to 135 ± 38 % of intact.

Conclusions

Testing demonstrated excellent predictive value of the parametric model, and that the FRSS attained the desired biomechanical performance developed with the model. A simple parametric model may allow efficient optimization of kinematic design parameters.     

Whip stitch versus grasping suture for tendon autograft

Purpose

During tendon autograft harvest, either a grasping suture or traditional whip stitch can be used to grasp tendon prior to definitive bone fixation. Their grip strength has not, to our knowledge, been compared. This article compares a needle-free suture technique to a standard whip stitch by testing grip strength in vitro.

Methods

Twelve uniform ovine flexor tendons were prepared; six tendons with a standard, non-locking whip stitch and six tendons with a grasping suture. All the samples were tested to failure in uniaxial tension in a materials testing machine. Load/displacement curves were generated, and qualitatively assessed and peak loads were compared.

Results

There were no significant differences between the groups in tendon length or diameter. Modes of failure between the groups, as characterised by the load/displacement curves, were quite distinct. Peak load to failure was lower in the utility suture group (mean peak load at failure 121.28 N) than the whip stitch group (mean peak load to failure 188.82 N). All failures in the utility suture group occurred when the suture snapped.

Conclusions

The grasping suture described here is weaker than a standard whip stitch but may be sufficiently strong to harvest and handle tendon autograft. A standard whip stitch remains the choice for definitive graft fixation.     

The biomechanical characteristics of arthroscopic tibial inlay techniques for posterior cruciate ligament reconstruction: in vitro comparison of tibial graft tunnel placement

Purpose

The hypothesis of the present study was that the biomechanical properties of arthroscopic tibial inlay procedures depend on tibial graft bone block position.

Methods

Five paired fresh-frozen human cadaveric knee specimens were randomized to a reconstruction with quadriceps tendon placing the replicated footprint either to the more proximal margin of the remnants of the anatomical PCL fibrous attachments (group A) or to the distal margin of the anatomical PCL fibrous attachments at the edge of the posterior tibial facet to the posterior tibial cortex in level with the previous physis line (group B). The relative graft-tibia motions, post cycling pull-out failure load and failure properties of the tibia-graft fixation were measured. Cyclic displacement at 5, 500 and 1,000 cycles, stiffness and yield strength were calculated.

Results

The cyclic displacement at 5, 500 and 1,000 cycles measured consistently more in group A without statistically significant difference (4.11?±?1.37, 7.73?±?2.73 and 8.18?±?2.75 mm versus 2.81?±?1.33, 6.01?±?2.37 and 6.46?±?2.37 mm). Mean ultimate load to failure (564.6?±?212.3) and yield strength (500.2?±?185.9 N) were significantly higher in group B (p?Conclusion Replicating the anatomical PCL footprint at the posterior edge of the posterior tibial facet yields higher pull-out strength and less cycling loading displacement compared to a tunnel position at the centre of the posterior tibial facet.     

Die arthroskopisch unterstützte transkapsuläre Refixation des Discus triangularis am Handgelenk

Objective

Refixation of the triangular fibrocartilage complex (TFCC) to the ulnar capsule of the wrist.

Indications

Distal TFCC tears without instability, proximal TFCC intact. Loose ulnar TFCC attachment without tear or instability.

Contraindications

Peripheral TFCC tears with instability of the distal radioulnar joint (DRUJ). Complex or proximal tears of the TFCC. Isolated, central degenerative tears without healing potential.

Surgical technique

Arthroscopically guided, minimally invasive suture of the TFCC to the base of the sixth extensor compartment.

Postoperative management

Above elbow plaster splint, 70° flexion of the elbow joint, 45° supination for 6 weeks. Skin suture removal after 2 weeks. No physiotherapy to extend pronation and supination during the first 3 months.

Results

In an ongoing long-term study, 7 of 31 patients who underwent transcapsular refixation of the TFCC between 1 January 2003 and 31 December 2010 were evaluated after an average follow-up interval of 116 ± 34 months (range 68–152 months). All patients demonstrated an almost nearly unrestricted range of wrist motion and grip strength compared to the unaffected side. All distal radioulnar joints were stable. On the visual analogue scale (VAS 0–10), pain at rest was 1 ± 1 (range 0–2) and pain during exercise 2 ± 2 (range 0–5); the DASH score averaged 10 ± 14 points (range 0–39 points). All patients were satisfied. The modified Mayo wrist score showed four excellent, two good, and one fair result. These results correspond to the results of other series.

Conclusion

Transcapsular refixation is a reliable, technically simple procedure in cases with ulnar-sided TFCC tears without instability leading to good results.