The influence of reverse-thread screw femoral fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendon

In arthroscopically assisted anterior cruciate ligament reconstruction using hamstring tendon graft, the graft rotates slightly as the femoral screw is inserted. Its final position tends to be in the anterior half of the tunnel in right knees, resulting in clinical laxity. To perform identical procedures on left and right knees, a reverse-thread screw was designed for femoral fixation in right knees. We prospectively studied 80 patients undergoing right-knee anterior cruciate ligament reconstruction with hamstring tendon autograft. Thirty-six patients underwent reconstruction with a standard screw and 44 underwent reconstruction with a reverse-thread screw. The same technique, performed by the same surgeon, was used on all patients. At 12 months' follow-up, the average side-to-side differences on arthrometry testing were 2.00 mm for the standard screw group and 0.95 mm for the reverse-thread screw group using a manual maximum test, and 1.66 mm and 1.00 mm, respectively, using the 20-pound test. Both differences were statistically significant. Of the standard group, 23% had a manual maximum difference of 3 mm or more, compared with 8% of the reverse-thread group. A significant difference was found between these two groups for Lachman test (77% with grade 0 for the standard group compared with 92% for the reverse group) but pivot shift and Lysholm knee score were not significantly different. The use of a reverse-thread screw for femoral fixation in right-knee anterior cruciate ligament reconstructions in men significantly decreased laxity at 12 months after surgery compared with standard screw fixation.     

A biomechanical evaluation of transcondylar femoral fixation of anterior cruciate ligament grafts

BACKGROUND: Interference screw fixation of the graft in anterior cruciate ligament reconstruction is considered the gold standard, but limited clinical experience suggests that transcondylar fixation is equally effective. PURPOSE: To compare transcondylar and interference screw fixation. STUDY DESIGN: Ex vivo biomechanical study. METHODS: Twenty pairs of unembalmed knees underwent anterior cruciate ligament reconstruction with patellar tendon autografts. In 1 knee of each pair, the bone plug was stabilized in the femoral tunnel with standard interference screws; in the other knee, transcondylar screws were used. Testing to failure occurred immediately or after 1000 cycles of sinusoidal loading (30 to 150 N) (20 paired reconstructions each). Fixation stiffness, strength, graft creep, displacement amplitude, and change in amplitude were measured and compared (repeated measures anaylsis of variance with Tukey test; P <.05). RESULTS: There was no significant difference in acute strength, maximum load within 3 mm, or stiffness between transcondylar fixation (410 +/- 164 N, 183 +/- 93 N, and 49.6 +/- 28 N/mm, respectively) and interference fixation (497 +/- 216 N, 206 +/- 115 N, and 61 +/- 37.8 N/mm, respectively). Similarly, there was no significant difference in cyclic strength, maximum load within 3 mm, or stiffness between transcondylar fixation (496 +/- 214 N, 357 +/- 82.9 N, and 110 +/- 27.4 N/mm, respectively) and interference fixation (552 +/- 233 N, 357 +/- 76.2 N, and 112 +/- 26.8 N/mm, respectively). Predominant modes of failure were bone plug pullout (transcondylar fixation) and tendon failure or bone plug fracture (interference fixation). CONCLUSIONS: Transcondylar screw fixation of the patellar tendon autograft into the femoral tunnel performed mechanically as well as interference screw fixation. CLINICAL RELEVANCE: The results suggest that transcondylar and interference screws provide similar fixation for anterior cruciate ligament reconstruction.     

Multistranded hamstring tendon graft fixation with a central four-quadrant or a standard tibial interference screw for anterior cruciate ligament reconstruction

BACKGROUND: Tibial fixation of hamstring tendon grafts has been the weak link in anterior cruciate ligament reconstruction. HYPOTHESIS: Use of a central four-quadrant sleeve and screw provides superior fixation when compared with standard interference screw fixation. STUDY DESIGN: Controlled laboratory study. METHODS: In eight pairs of cadaveric knees each anterior cruciate ligament was reconstructed using either an interference screw or a central sleeve and screw on the tibial side. The specimens were then subjected to cyclic loading followed by a load-to-failure test. RESULTS: The load required to cause 1 and 2 mm of graft laxity, defined as the separation of the femur and the tibia at the points of graft fixation, was significantly greater with the sleeve and screw than with the interference screw (at 2 mm: sleeve and screw, 216.1 +/- 30.1 N; interference screw, 167.0 +/- 33.2 N). The force at initial slippage for each of the graft strands was significantly higher with use of the central sleeve and screw. CONCLUSIONS: The four-quadrant sleeve and screw device may provide greater surface area for healing of hamstring tendon grafts and allow equal tensioning of graft strands before fixation. These factors are associated with increased strength of fixation and reduced laxity of the graft after cyclic loading. Clinical Relevance: Use of the central four-quadrant sleeve and screw system offers increased strength of fixation in anterior cruciate ligament reconstruction with hamstring tendon graft.     

Behavior of the graft within the bone tunnels following anterior cruciate ligament reconstruction, studied by cinematic magnetic resonance imaging

The behavior of a ligament graft following cruciate ligament reconstruction is still an area of limited knowledge. Cinematic magnetic resonance imaging (MRI) offers the possibility of visualizing the graft, including the graft tunnels and fixation during knee motion. Twenty-three patients underwent cinematic MRI (0.2 T; Artoscan) mean ¶23.4 months (range 14–39 months) after autologous anterior cruciate ligament reconstruction (eight bone-tendon-bone, seven semitendinosus-gracilis, and eight iliotibial band). The images were read without knowledge of the clinical condition or the type of surgery performed. Signal intensity and continuity of the anterior cruciate ligament reconstruction and movement of the graft in the tibial or femoral tunnel anteriorly and posteriorly were noted. In two of the 23 patients the graft (semitendinosus-gracilis) moved in the tibial canal. The initial 9-mm tunnel had expanded by 2 mm in the anteroposterior direction at the entrance to the joint space. Only these two had a slight knee laxity, with a side-to-side difference in anterior translation measured by the KT-2000 of 4 and ¶5 mm. No movement was observed in any of the femoral tunnels. Cinematic MRI thus makes it possible to study graft behavior within the bone tunnels.     

Avoiding allograft length mismatch during anterior cruciate ligament reconstruction: patient height as an indicator of appropriate graft length

BACKGROUND: Given the increasing use of allografts in anterior cruciate ligament reconstruction, selection of appropriate-sized grafts may help individual surgeons as well as the efficiency of the overall system for graft distribution. HYPOTHESIS: Recipient patient height can predict the desired length for the tendinous portion of a patellar bone-tendon-bone allograft in anterior cruciate ligament reconstruction. STUDY DESIGN: Cohort study (Prognosis); Level of evidence, 2. METHODS: A series of 414 knees in 392 consecutive patients undergoing magnetic resonance imaging evaluation of knee pain were enrolled in the study. Data collected from magnetic resonance imaging included patella and patellar tendon length and intraarticular length of the anterior cruciate ligament. Patient age, height, weight, and gender were recorded. Linear regression analysis assessed the correlation between patient height and intraarticular length of the anterior cruciate ligament as well as patellar tendon length. The effect of variance in age, weight, and gender on anterior cruciate ligament intraarticular length was also measured. RESULTS: A strong positive correlation was found between intraarticular length of the anterior cruciate ligament and patient height (Pearson r = 0.73; P < .001). Anterior cruciate ligament length (y, in millimeters) as a function of height (x, in inches) can be expressed as y = 1.17x - 41.29. As a function of height (x, in centimeters), anterior cruciate ligament length (y, in millimeters) can be expressed as y = 0.4606x - 41.29. Age, gender, and weight did not significantly influence this relationship. A weak positive association was found between patient height and patellar tendon length. CONCLUSION: Patient height can predict the desired length of the tendinous portion of a patellar bone-tendon-bone allograft. An addition of 10 mm is made to the predicted anterior cruciate ligament length to allow for aperture tibial and femoral fixation. Patellar bone-tendon-bone allografts can be requested based on recipient patient height as follows: 5 ft, 0 in to 5 ft, 6 in: tendinous length/total length, 45 mm/95 mm; 5 ft, 7 in to 6 ft, 1 in: 50 mm/100 mm; > 6 ft, 1 in: 55 mm/105 mm.     

Structural properties of lateral collateral ligament reconstruction at the fibular head

BACKGROUND: Anatomical reconstruction of a ruptured lateral collateral ligament using allograft tissue secured within the fibular head with an interference screw has been described. HYPOTHESIS: Interference fixation at the fibular head does not reproduce the strength of the intact ligament. STUDY DESIGN: Controlled laboratory study. METHODS: Ten intact lateral collateral ligaments were tested to failure. The distal fixation of 11 ligaments reconstructed with a graft including a bone plug and 11 ligaments reconstructed with a graft without a bone plug were also tested. RESULTS: The reconstructed ligaments consistently failed at the fibular head. The intact specimens predominately failed through ligament rupture. The mean strength and stiffness values were 460 +/- 163 N and 82 +/- 25 N/mm, respectively, for the intact ligaments, 113 +/- 40 N and 36 +/- 10 N/mm, respectively, for reconstruction with a bone plug, and 135 +/- 81 N and 34 +/- 14 N/mm, respectively, for reconstruction without a bone plug. The strength and stiffness were significantly (P < .05) greater for the intact ligaments than for either reconstruction group. The variation in strength was significantly larger for reconstruction without a bone plug than for reconstruction with a bone plug. CONCLUSION: Tension applied to lateral collateral ligaments reconstructed using fibular interference fixation should be limited immediately after surgery. Soft tissue fixation should be employed with care because of the inconsistency in the failure strength. CLINICAL RELEVANCE: Although fibular interference fixation is increasingly being described in the literature, the properties of reconstructed lateral collateral ligaments have not previously been quantified.     

Clinical outcome of anterior cruciate ligament reconstruction with quadrupled hamstring tendon graft and bioabsorbable interference screw fixation

BACKGROUND: To date, there has been no publication of clinical follow-up data on patients who have undergone quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable screw fixation. PURPOSE: To report the results of quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation. STUDY DESIGN: Retrospective review. METHODS: Sixty-five patients (66 knees) were retrospectively identified by chart review as having undergone quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation with a minimum 2-year follow-up. RESULTS: Data were collected on 48 knees in 47 patients (73%) at an average 30.2 months (range, 24 to 43) after surgery. Thirty-six patients (37 knees) returned for clinical evaluation (56% return) and subjective follow-up only was obtained in 11 patients (17%). The mean Lysolm knee score was 91 (range, 45 to 98), with a mean of 97 for the uninvolved knee. The mean Tegner activity score was 5.7 (range, 3 to 7). The KT-1000 arthrometer mean side-to-side difference for manual maximum displacement was 2.03 mm (range, -1 to 8). The mean International Knee Documentation Committee knee score was 83 (range, 47 to 100). Patients who underwent associated partial meniscectomy or meniscal repair had significantly lower International Knee Documentation Committee scores than patients without associated procedures (P < 0.01). CONCLUSIONS: Quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation is comparable with other methods of anterior cruciate ligament reconstruction in terms of patient satisfaction, knee stability, and function.     

Revision anterior cruciate ligament reconstruction with hamstring tendon autograft: 5- to 9-year follow-up

BACKGROUND: The results of revision anterior cruciate ligament reconstruction are limited in the current literature, and no studies have previously documented the outcome of revision anterior cruciate ligament reconstruction using solely hamstring tendon grafts. HYPOTHESIS: Revision anterior cruciate ligament reconstruction with 4-strand hamstring tendon graft affords acceptable results and is comparable to reported outcomes with the bone-patellar tendon-bone graft. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Fifty-seven consecutive revision anterior cruciate ligament reconstructions with the hamstring tendon graft and interference screw fixation were assessed a mean time of 89 months (range, 60-109 months) after surgery. Assessment included the International Knee Documentation Committee knee ligament evaluation, instrumented laxity testing, and radiologic examination. RESULTS: Of the 50 knees reviewed, 5 (10%) had objective failure of the revision anterior cruciate ligament reconstruction. Of the 45 patients with functional grafts, knee function was normal or nearly normal in 33 patients (73%). An overall grade of normal or nearly normal was found in 56% of patients. The mean side-to-side difference on manual maximum testing was 2.5 mm (range, -1 to 4 mm). Degenerative changes on radiographs were identified in 23% of patients at the time of surgery, increasing to 56% of patients at review. The status of the articular cartilage at the time of revision surgery was the most significant contributor to successful outcome. CONCLUSION: Revision anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation affords acceptable results at a minimum of 5 years' follow-up. Good objective results can be obtained, but subjectively, the results appear inferior to those of primary anterior cruciate ligament reconstruction in the literature, which may be related to the high incidence of articular surface damage in this patient population. We recommend that, when available, hamstring tendon autografts should be considered for revision anterior cruciate ligament reconstruction.     

Posterior cruciate ligament reconstruction with the quadriceps tendon in chronic injuries

We reviewed 18 patients (knees) operated on because of chronic PCL insufficiency. Preoperatively all the patients were severely disabled and showed a posterior drawer of 10 mm or more. A quadriceps tendon autograft was implanted using an open technique, direct posterior approach, and fixation to the tibia. A free semitendinosus graft was used to reconstruct the lateral collateral ligament in six knees and the medial collateral ligament in two. The patients were reviewed with a mean follow-up of 3.5 years (range 2-5.5) using the IKDC form. Stability was evaluated by stress radiography using the Telos device. The mean side-to-side difference in posterior tibial displacement at 70 degrees of knee flexion at follow-up was 4.8 mm; the side-to-side difference was less than 5 mm in 77% of cases. A side-to-side difference less than 2 mm in lateral joint line opening was found in five of six knees with a lateral collateral ligament reconstruction. Posterior tibial translation was similar in the knees with and those without collateral ligament reconstruction. Only one patient complained of significant pain and giving-way at follow-up. Patellofemoral crepitation was present in nine knees at follow-up although it was symptomatic only in one. The results of this series suggest that posterior cruciate ligament reconstruction using an autologous quadriceps tendon is a valuable option to reconstruct these severe injuries.     

Bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction: an in vitro comparison of mechanical behavior under failure tensile loading and cyclic submaximal tensile loading

BACKGROUND: Secure fixation is an important factor in the success of anterior cruciate ligament reconstruction. HYPOTHESIS: There is no difference in the mechanical behavior of reconstructions from method of fixation or method of testing. STUDY DESIGN: Controlled laboratory study. METHODS: Anterior cruciate ligament reconstructions were performed with bone-patellar tendon-bone grafts in 48 human cadaveric knees. Three different fixation methods (Endobutton, interference screw, suture-post fixation) were compared under failure tensile loading and cyclic submaximal tensile loading. RESULTS: No difference was observed in ultimate load among the three techniques. Stiffness of the grafts was significantly lower for the suture technique than for the interference screw technique. Cyclic loading revealed significantly different failure rates: 0% of the Endobutton, 38% of the interference screw, and 100% of the suture-post groups. The relative movement of the femoral bone plug and the migration of the bone plug out of the femoral canal were lowest in the interference screw group. CONCLUSIONS: The suture-post fixation is not recommended. The interference screw technique showed the best results, but results were age-dependent, suggesting its best use is in younger patients. The Endobutton technique is recommended for older patients. Clinical Relevance: Results of testing are useful to the surgeon in making a choice of reconstruction technique.     

Pullout strength of tibial graft fixation in anterior cruciate ligament replacement with a patellar tendon graft: interference screw versus staple fixation in human knees

The endoscopic single incision technique for anterior cruciate ligament (ACL) reconstruction with a femoral half-tunnel may lead to a graft/tunnel mismatch and subsequent protrusion of the block from the tibial tunnel. The typical tibial fixation with an interference screw is not possible in these cases. Fixation with staples in a bony groove inferior to the tunnel outlet can be used as an alternative technique. Current literature does not provide biomechanical data of either fixation technique in a human model. This study was performed to evaluate the primary biomechanical parameters of this technique compared with a standard interference screw fixation of the block. Fifty-five fresh-frozen relatively young (mean age 44 years) human cadaver knee joints were used. Grafts were harvested from the patellar tendon midportion with bone blocks of 25 mm length and 9 mm width. A 10-mm tibial tunnel was drilled from the anteromedial cortex to the center of the tibial insertion of the ACL. Three different sizes of interference screws (7 × 30, 9 × 20, 9 × 30 mm) were chosen as a standard control procedure (n = 40). For tibial bone-block fixation the graft was placed through the tunnel, and the screw was then inserted on the cancellous or the cortical surface, respectively. Fifteen knees were treated by staple fixation. A groove was created inferior to the tunnel outlet with a chisel. The bone block was fixed in this groove with two barbed stainless steel staples. Tensile testing in both groups was carried out under an axial load parallel to the tibial tunnel in a Zwick testing machine with a velocity of 1 mm/s. Dislocation of the graft and stiffness were calculated at 175 N load. Maximum load to failure using interference screws varied between 506 and 758 N. Load to failure using staples was 588 N. Dislocation of the graft ranged between 3.8 and 4.7 mm for interference screw fixation and was 4.7 mm for staples. Stiffness calculated at 175 N load was significantly higher in staple fixation. With either fixation technique, the recorded failure loads were sufficient to withstand the graft loads which are to be expected during the rehabilitation period. Staple fixation of the bone block outside of the tunnel resulted in a fixation strength comparable to interference screw fixation. Received: 2 September 1996 Accepted: 30 January 1997     

Peroneal nerve damage by bicortical tibial screw in ACL reconstruction

Arthroscopically assisted anterior cruciate ligament reconstruction is regarded as a minimally invasive surgery with low morbidity but complications still occur. Reports of neurovascular injuries related to graft harvesting, tunnel placement, or graft fixation are limited. A rare case of peroneal nerve injury related to hardware used for graft fixation in the tibial in a 28-year-old female patient who underwent an anterior cruciate ligament reconstruction surgery using a patellar tendon graft (bone-tendon-bone graft) is presented. Post-operatively, the patient presented with clinical signs of peroneal nerve damage and a reduced range of motion of the knee. Plain radiographs of the knee showed the bicortical screw which used for tibial fixation of the graft, penetrating the fibula and projecting beyond the lateral cortex of the fibular neck. The patient was treated with removal of the hardware and the graft. Intensive physiotherapy resulted in gradual improvement and at 6 months after the second operation the patient regained full range of motion of the knee and almost full muscle strength performing her daily activities without any difficultly and she is at the moment unwilling to undergo further procedure.     

Drill hole position in endoscopic anterior cruciate ligament reconstruction Results of an advanced arthroscopy course

In 24 cadaver knees the anterior cruciate ligament (ACL) was replaced by a bone-tendon-bone patellar tendon autograft in an endoscopic technique. This was carried out during an advanced arthroscopy course after intensive instruction and practice on a plastic model. When the knees were opened and evaluated according to the recent orthopaedic literature, only four good results with correct tunnels and a non-impinging graft were found. In 12 knees the femoral tunnel was too far anterior (10) or had broken through the posterior femoral cortex (2). In 6 knees the tibial tunnel was too far anterior (2) or too far posterior (4). The notchplasty was insufficient in 6 knees. We conclude that endoscopic ACL reconstruction cannot be mastered after attending a course alone. Expert help is necessary during the first clinical cases.     

Graft force-setting technique in reconstruction of the anterior cruciate ligament

The objective of this work was to present a method for controlling the mechanical state of the knee during graft fixation in an ACL reconstruction; that is, adjusting the unloaded length of the graft at the time of fixation so that the force-carrying characteristics of the graft match that of the intact ACL, when the normal and reconstructed knees are subjected to the same external load. To demonstrate the new method, an experimental knee testing system was used to measure ligament and graft forces with buckle transducers, as external loads were applied to five fresh knee specimens with a pneumatic load apparatus. ACL and collateral ligament force data were collected as anteriorly directed loads of 90 N (20 pounds) were applied at 0 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion in the normal intact knee and the same knee following ACL excision. A composite graft was prepared, consisting of distally based semitendinosus and gracilis autogenous tissue augmented with the Kennedy Ligament Augmentation Device. Femoral fixation was obtained using a fixation plug that was inserted through the lateral femoral condyle. With a 90 N anterior tibial load applied at 30 degrees of flexion and a single buckle transducer measuring the total composite graft force, the graft length was varied using the fixation plug until the force matched that seen by the intact ACL under the same loading condition. The graft was then clamped in the fixation plug and the anterior load sequence at the four flexion angles was applied to this reconstructed knee state.(ABSTRACT TRUNCATED AT 250 WORDS)     

Femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction: biomechanical evaluation of different fixation techniques: is there an acute angle effect?

BACKGROUND: The literature provides little biomechanical data about femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction. HYPOTHESIS: A hybrid fixation technique with use of an undersized screw has sufficient strength to provide secure fixation of posterior cruciate ligament grafts. Additional aperture fixation with a biodegradable interference screw can prevent graft damage that might be caused by an acute angle on the edge of the femoral tunnel. STUDY DESIGN: Controlled laboratory study. METHODS: In part 1, extracortical fixation of posterior cruciate ligament reconstructions with quadrupled porcine flexor digitorum grafts to simulate human hamstring grafts was compared with hybrid fixation methods using 6-, 7-, and 8-mm screws. Groups were tested in cycling loading with the load applied in line with the bone tunnel. In part 2, extracortical fixation was compared with hybrid fixation using a 1-mm undersized screw anterior and posterior to the graft. Structural properties and graft abrasion were evaluated after cyclic loading with the load applied at 90 degrees to the tunnel. In each group, 8 porcine knees were tested. RESULTS: In part 1, stiffness, maximum load, and yield load were significantly higher for hybrid fixation than for extracortical fixation. Hybrid fixation with an 8-mm screw resulted in higher yield load than with a 7-mm screw. In part 2, graft laceration was more pronounced in specimens with extracortical fixation than with hybrid fixation. Posterior screw placement was superior to the anterior position. CONCLUSION: For all parameters, hybrid fixation with an interference screw provided superior structural results. No relevant disadvantages of undersized screws could be found. Graft damage due to abrasion at the edge of the femoral bone tunnel was reduced by use of an interference screw. The posterior screw placement seems favorable. CLINICAL RELEVANCE: Hybrid fixation of hamstring grafts in posterior cruciate ligament reconstruction is superior to extracortical fixation alone with no relevant disadvantages of undersized screws. The results raise the suspicion of an acute angle effect of the femoral bone tunnel.     

Comparison of femoral fixation methods for anterior cruciate ligament reconstruction with patellar tendon graft: a mechanical analysis in porcine knees

The aim of the present study was to evaluate the structural properties of femur–patellar tendon graft complex in anterior cruciate ligament (ACL) reconstruction using different femoral fixation devices. Type of study is biomechanical testing. An ACL reconstruction was performed on 40 cadaver porcine knees, using patellar tendon (PT) graft. Specimens were divided into four groups according to the femoral fixation: interference absorbable screw (Group A), metallic setscrew (Group B), absorbable pins (Group C), and a combination of metallic setscrew and pin (Group D). Other ten knees were used as controls. On each sample, a cyclic loading test, then a load-to-failure test were performed. Elongation after 1,000 loading cycles, ultimate failure load, yield load, stiffness, deformation at the yield point, and mode of failure were recorded. Kruskal–Wallis test and Tukey test were used to compare the differences between groups. The lowest mean elongation after 1,000 load cycles was observed for Group B (1.7 ± 1.4 mm) and D (1.2 ± 0.3 mm). Ultimate failure load of Group D (1,021.8 ± 199.4 N) was comparable with that of normal ACL (1,091.2 ± 193.3 N) and PT graft (1,140.6 ± 285.7 N). All other groups were lower than the controls. For mean stiffness, all the groups, excepting for Group D (172.8 ± 40.4 N/mm), were significantly lower than PT control group (216 ± 78.4 N/mm). Mode of failure was graft pullout for Groups A and B, distal pin breakage for Group C, and midsubstance graft rupture in 80% of the cases for Group D. Only combined compression and suspension fixation did not show significantly different structural properties in comparison with normal ACL and PT graft. Furthermore, it showed no risk of graft pullout or hardware breakdown in comparison with other fixation devices.     

MRI in ACL reconstructive surgery with PDLLA bioabsorbable interference screws: evaluation of degradation and osteointegration processes of bioabsorbable screws

PURPOSE: Anterior cruciate ligament (ACL) reconstructive surgery has seen significant progress since bioabsorbable interference screws have replaced synthetic metallic screws for ligament graft fixation within the femoral and tibial osseous tunnel. Our study compared the MR images of patients who underwent ACL reconstruction using bioabsorbable interference screws with those of patients who underwent ACL reconstruction using metallic screws to evaluate the MR aspects of degradation and osteointegration processes of bioabsorbable interference screws post-operatively. MATERIALS AND METHODS: Between September 1999 and December 2002 we performed MRI on 40 patients who underwent arthroscopic ACL reconstruction with patellar tendon auto-graft using PDLLA bioabsorbable screws in 35 cases and metallic screws in 5 cases. After surgery, all patients underwent an intensive rehabilitation programme along with clinical evaluation using the standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC) and radiological examinations. MR studies were performed 1, 2 and 3 years post-operatively using a 0.5-Tesla MR scanner with T1- and T2*-weighted and STIR sequences. RESULTS: Thirty-three patients were clinically classified as group A IKDC (full return to sports activity) and 7 patients as group B IKDC. No foreign-body reaction was found in patients treated with bioabsorbable interference screws, both from a clinical point of view and from laboratory exams. Ferromagnetic artefacts were found in all patients treated with metallic interference screws. In patients with bioabsorbable interference screws, degradation of the screws and absence of significant artefacts allowed correct evaluation of the signal of the reconstructed ligament throughout its length, the osseous tunnels and the joint cavity. In 34 of 35 patients with bioabsorbable interference screws, the screw could not be detected due to complete degradation. In 8, 12 and 4 cases, a small cyst-like formation due to screw hydrolysis was present at the screw site within 1, 2 and 3 years from surgery respectively. Only in 4 cases was the process of osteointegration of the screw and bone plug complete 3 years after the operation, with consequent restoration of bone morphology. DISCUSSION AND CONCLUSIONS: The use of bioabsorbable interference screws is a valuable alternative to synthetic metallic fixation implants as the absence of artefacts allows correct post-operative MR follow-up. MRI is the only technique able to visualize all the portions of the transplant and to evaluate the healing process. Bioabsorbable interference screws usually degrade within one year. However, full osteointegration requires a long time and may not be complete 3 years after surgery. The presence of cyst-like formations at the screw site has to be regarded as a normal feature of the screw degradation process. Therefore, the use of bioabsorbable interference screws is recommended as it enables MR follow-up of the knee after ACL reconstruction.     

The influence of supplementary tibial fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendons in female patients

BACKGROUND: Female patients undergoing arthroscopic anterior cruciate ligament reconstruction with a hamstring tendon graft developed increased postoperative laxity compared to male and female patients who had reconstruction using a patellar tendon graft. This difference may be due to graft slippage in less dense female tibial bone. HYPOTHESIS: Reinforcement of tibial fixation of the hamstring tendon graft in women by supplementary methods may reduce laxity. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 2. METHODS: Fifty-six female patients divided into 2 groups (standard tibial fixation with 7 x 25-mm metal interference screw versus metal interference screw with supplementary staple fixation) were followed for 2 years. RESULTS: After 2 years, the mean side-to-side difference using KT-1000 arthrometer manual maximum measurements was 1.8 mm (standard group) and 1.1 mm (staple group) (P=.05). The percentage of patients with a side-to-side difference of <3 mm did not differ significantly between the 2 groups (P=.66): 88.8% of the standard group versus 90.5% of the staple group. A grade 0 Lachman test result was present in 63% of the standard group and 86% of the staple group (P=.04). Kneeling pain was experienced by 7% of the standard group and 29% of the staple group (P=.05). CONCLUSIONS: Supplementary tibial fixation in female patients undergoing anterior cruciate ligament reconstruction with hamstring tendon graft in addition to a single-size screw significantly improves laxity measurements and clinical stability assessment 2 years after surgery. However, this improvement is at the cost of increased kneeling pain.     

Revision ACL reconstruction using autogenous patellar tendon graft

This retrospective study examined revision anterior cruciate ligament reconstruction using a bone-tendon-bone autograft of the patellar ligament. We followed up 44 patients (mean age 27.9 years) for an average of 41.2 months. Clinical examination with the Lachmann and pivot shift tests showed clearly improved stability; KT-1000 arthrometer measurements had a mean difference of 3.5 mm in side-to-side comparison. The evaluated knee scores were significantly improved (P<0.01); the median Lysholm score was 85 and the median Tegner activity score 5.0 at follow-up. In the IKDC ranking system 75.0% of knees were rated normal or nearly normal (grades A and B). According to a modified Fairbank scale, progression of radiographic signs of osteoarthritis was noted in 36.4%. There was a significant difference (P<0.05) in progression of radiographic signs of osteoarthritis between patients with major (grades III, IV) versus minor (grades I, II) lesions of the articular cartilage surface and between knees with versus without extensive synovitis due to previous synthetic graft reconstruction (P<0.05). Revision anterior cruciate ligament reconstruction using an autogenous patellar tendon graft shows good results with improved knee function compared to the prerevision status and is in line with various operative techniques described in the literature. Progression of osteoarthritis must be expected in patients with major lesions of the articular cartilage surface and knees with long-term extensive synovitis due to previous anterior cruciate ligament reconstruction using synthetic grafts.     

The load of an implanted graft during and after fixation in anterior cruciate ligament reconstruction

Although the importance of initial graft load has been discussed in the literature, it has not been confirmed whether a surgeon can provide the desired load to an implanted graft in anterior cruciate ligament reconstruction. The purpose of this study was to compare the set force (initial load given to the graft before fixation) and residual load in the implanted graft using three different fixation techniques. A total of ninety porcine knees were tested using bone–patellar tendon–bone autograft. Each bone–tendon–bone autograft was fixed to the tibia with either the interference-fit screw, fixation post, or button technique. Graft load was monitored during fixation procedures, and for 10 min after fixation. Residual graft load with each fixation technique exhibited unique features. Highest graft load was obtained by the interference-screw fixation technique; however, the graft was usually over-loaded beyond the intended set force with this technique. In the fixation-post technique, the load of the graft increased while the screw was retightened. The graft load in the button-fixation technique was low, probably due to slight slippage of the button. When the graft was fixed under maximum manual tension, the graft loads at completion of fixation for the interference fit screw, fixation post, and button techniques were 116.3, 54.2, and 25.9 N respectively.