Femoral Cross-pin Research Articles

Comparison of Outcomes of Anterior Cruciate Ligament Reconstructions Using Patellar Tendon or Hamstring Tendon Autografts with Femoral Cross-pin Fixation

Aim: In this study, we aimed to compare outcomes of anterior cruciate ligament (ACL) reconstructions using bone–patellar tendon–bone graft (BPTG) or hamstring tendon graft (HTG) with cross-pin fixation at the femoral side. Materials and Methods: The retrospective observational study included records of 100 patients who underwent ACL reconstruction with femoral cross-pin fixation between May 2008 and August 2012. The patients were divided into two groups according to the graft type used: the BPTG group and the HTG group. The preoperative and postoperative 6th-month Tegner Lysholm Knee Scoring Scale (TLKS) scores, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF) scores, and Lachman test results were compared. The effects of meniscus lesion presence on the outcomes were also investigated. Results: Of the 100 patients, 93 were male and 7 female. The HTG and BPTG groups consisted of 62 and 38 patients, respectively. The mean age was 24.1±4.9 (18–38) years for the HTG group and 32.1±6.8 (21–54) years for the BPTG group. The mean pre- and postoperative TLKS scores were respectively 50.5 and 94.3 in the BPTG group, and 49.9 and 95.2 in the HTG group. The mean pre- and postoperative IKDC-SKF scores were 51.3 and 95.6 in the BPTG group, and 51.8 and 95.6 in the HTG group. The postoperative score improvement was statistically significant in all patients (p<0.05), but there was no significant difference between the two groups. The postoperative improvement in knee stability was statistically significant in all patients (p<0.05). The postoperative score improvement was less in patients with meniscal injury (p<0.05). Discussion and Conclusion: We found no significant difference between the two groups in terms of functional knee scores. However, the presence of meniscus lesions negatively affects the postoperative outcomes.

Anterior Cruciate Ligament Reconstruction in Young Females: Patellar versus Hamstring Tendon Autografts

Objectives:Female athletes are two to eight times more likely to suffer a primary ACL tear than males. Although ACL reconstruction can successfully return many athletes to their pre-injury sports, re-injury to the ipsilateral or contralateral knee can occur in over 20% of young athletes. Both female sex and younger age have been shown to be risk factors for graft failure. The optimal graft choice for this high-risk population of young female athletes remains unknown and poorly studied. We compared the clinical outcomes in young female patients who underwent ACL reconstruction at our institution using bone-patellar tendon-bone (BTB) and quadrupled hamstring (HS) autografts.Methods:Female patients aged 15-25 who underwent primary ACL reconstruction at our institution between January 2012 and May 2015 using either BTB or HS autograft were included in our review. Patients were further sub-divided into 2 age groups, 15-20 and 20-25. Patients with a prior history of ACL injury to either knee, or those with multiligament injury were excluded. Graft choice and fixation method were documented from a review of operative records. Medical records were reviewed to document the occurrence of chondral, meniscal or ligamentous injury to the ipsilateral or contralateral knee in the first two years following ACL reconstruction. Comparisons were made using the chi-square test with statistical significance set at p < 0.05.Results:A total of 256 females were included in our review with 175 in the BTB group and 81 in the HS group. There was no difference between the groups with regards to average age or time to follow-up. The majority of patients in both groups, 80% of the BTB group and 77.8% of the HS group, were between the ages of 15-20. Interference screw fixation was used in all BTB cases and 63.0% of HS cases. In the remainder of HS cases, femoral suspension and tibial screw (27.2%), and femoral cross-pins and tibial screw (9.9%) were used. In our series, 22.2% of hamstring grafts were augmented with allograft due to inadequate size. Overall, graft re-tear occurred in 6.9% of BTB patients and 12.3% of HS patients [p=0.16]. Contralateral ACL tear occurred in 7.4% of BTB patients and 6.2% of HS patients [p=0.72]. Sub-group analysis showed that 75% of BTB and 100% of HS graft re-tears occurred in females aged 15-20. Within this group, there was a significantly lower rate of graft re-tears in the BTB group (6.4%) when compared to the HS group (15.9%) [p=0.04]. Allograft augmentation was used in four of the ten HS grafts that re-tore. The risk of failure with hamstring augmentation with allograft (4/18, 22.2%) was higher than that of hamstring autograft alone (6/63, 9.5%), but this difference was not significant [p=0.18].Conclusion:The results of our study indicate that BTB autograft led to fewer graft re-tears compared to HS autograft following ACL reconstruction in female patients aged 15-20. However, this difference was not observed in females aged 20-25. Thus, further investigation regarding optimal graft choice is warranted in this age group.

Long-term outcome of an intra-articular allograft technique for treatment of spontaneous cranial cruciate ligament rupture in the dog.

To determine the 12-month outcome in dogs with spontaneous cranial cruciate ligament (CCL) rupture after repair with an intra-articular decellularized allograft. Prospective pilot case series. Ten client-owned dogs with unilateral CCL rupture. An intra-articular, decellularized, deep digital flexor tendon allograft was secured in the stifle with a femoral cross pin and tibial spiked washers and screws. An interference screw was placed in the tibial tunnel. Dogs were evaluated with an owner questionnaire, radiographs, and force platform gait analysis before and 2, 6, and 12 months after surgery. Owners reported improvement in level of pain and mobility throughout the study, especially over the first 6 months. Peak vertical force and vertical impulse improved across all time points. Ground reaction force asymmetry index for peak vertical force and vertical impulse at 12 months showed 3 dogs within a normal index (<6%), 4 dogs as nonvisibly lame (6-20%), and 3 dogs as visibly lame (≥20%). For most dogs, osteoarthritis scoring did not change over the 12-month period and some femoral-tibial translation was detected on standing horizontal beam radiographs. Intra-articular repair using a decellularized allograft can provide functional clinical outcomes in dogs with CCL disease. A better understanding of long-term engraftment after this procedure is needed.

Reverse Anterior Cruciate Ligament Reconstruction Fixation: A Biomechanical Comparison Study of Tibial Cross-Pin and Femoral Interference Screw Fixation

To evaluate the biomechanical performance of tibial cross-pin (TCP) fixation relative to femoral cross-pin (FCP), femoral interference screw (FIS), and tibial interference screw (TIS) fixation. We randomized 40 porcine specimens (20 tibias and 20 femurs) to TIS fixation (group 1, n= 10), FIS fixation (group 2, n= 10), TCP fixation (group 3, n= 10), or FCP fixation (group 4, n= 10) and performed biomechanical testing to compare ultimate load, stiffness, yield load, cyclic displacement, and load at 5-mm displacement. We performed cross-pin fixation of the looped end and interference screw fixation of the free ends of 9-mm-diameter bovine extensor digitorum communis tendon grafts. Graft fixation constructs were cyclically loaded and then loaded to failure in line with the tunnels. Regarding yield load, FIS was superior to TIS (704 ± 125N vs 504 ± 118N, P= .002), TCP was superior to TIS (1,449 ±265N vs 504 ± 118N, P < .001), and TCP was superior to FCP (1,449 ± 265N vs 792 ± 397N, P < .001). Cyclic displacement for FCP was superior to TCP. Cyclic displacement for TIS versus FIS showed no statistically significant difference (2.5 ± 1.0mm vs 2.2 ± 0.6mm, P= .298). Interference screw fixation consistently failed by graft slippage, whereas TCP fixation failed by tibial bone failure. FCP fixation failed by either femoral bone failure or failure elsewhere in the testing apparatus. Regarding yield load, TCP fixation performed biomechanically superior to the clinically proven FCP at time zero. Because TIS fixation shows the lowest yield strength, it represents the weak link, and combined TCP-FIS fixation theoretically would be biomechanically superior relative to combined FCP-TIS fixation with regard to yield load. Cyclic displacement showed a small difference in favor of FCP over TCP fixation and no difference between TIS and FIS. Time-zero biomechanics of TCP fixation paired with FIS fixation show that this method of fixation can be considered a potential alternative to current practice and may pose clinical benefits in different clinical scenarios of anterior cruciate ligament reconstruction.

Breakage of the Femoral Cross-Pin with Impending Rupture of the Popliteal Vessels after Anterior Cruciate Ligament Reconstruction

24세의 남자 환자로 동아대학교병원 내원 3주 전 지역 병원에서 전방십자인대 재건술을 시행하였다. 지역 병원에서의 재건술에 는 transtibial technique을 이용하여 대퇴부 터널을 만든 뒤 동종 아킬레스건을 삽입하였고 대퇴골은 cross-pin system인 Rigidfix (Depuy Mitek Inc., Raynham, MA, USA)를 이용하여 고정하였으 며 경골은 생체흡수성 간섭 나사와 4.5 mm 피질골 나사를 워셔와 함께 고정하였다. 술 후 2주경 수동적 관절 운동을 90까지 시행 하였으며 당시 특별한 통증이나 불편감 등의 문제는 없다고 판단 하여 부분 체중 부하를 시행하였다고 하였다. 그러나 환자가 술 후 16일경 관절 운동 도중 무릎에서 ‘뚝’하는 소리가 들리는 것을 인지하여 자기공명영상 촬영을 비롯한 추가적인 검사를 시행한 후 대퇴골 cross-pin의 파열 의심 소견과 후방의 신경혈관의 손상 이 우려되어 본원 응급실로 전원되었다. pISSN : 1226-2102, eISSN : 2005-8918 350

Biomechanical analysis on transverse tibial fixation in anterior cruciate ligament reconstructions

ObjectiveTo verify whether the combination of tibial cross pin fixation and femoral screw fixation presents biomechanical advantages when compared to femoral cross pin fixation and tibial screw fixation for the reconstruction of the anterior cruciate ligament (ACL). MethodsThirty-eight porcine knees and bovine extensor digitorum tendons were used as the graft materials. The tests were performed in three groups: (1) standard, used fourteen knees, and the grafts were fixated with the combination of femoral cross pin and a tibial screw; (2) inverted, used fourteen knees with an inverted combination of tibial cross pin and a femoral screw; (3) control, ten control tests performed with intact ACL. After the grafts fixation, all the knees were subjected to tensile testing to determine yield strength and ultimate strength. ResultsThere was no statistically significant difference in survival techniques in regard to strength, yield load and tension. There was a higher survival compared in the standard curves of yield stress (p<0.05). ConclusionThere is no biomechanical advantage, observed in animal models testing, in the combination of tibial cross pin fixation and femoral screw when compared to femoral cross pin fixation and tibial screw.

Evaluation of Short Term Outcomes of Transportal Femoral Cross Pin Fixation in Anterior Cruciate Ligament Reconstruction

Objectives:Many fixation techniques are currently in use for femoral side graft fixation at ACL reconstruction surgery. Short term success following ACL reconstruction highly depends on fixation strength of the graft. In this study we report short term results of anterior cruciate ligament reconstruction using double hamstring tendon autograft using double cross pin for femoral tunnel fixation.Methods:Between years 2009 and 2013, 51 male adult anterior cruciate ligament injury cases treated surgically, in a single center, with at least one year follow up were investigated. Professional athletes, multi-ligamentous instability cases, cases requiring meniscus repair or further treatment for chondral injuries and cases with concomitant medial and lateral meniscus lesions were not included in the study. Femoral tunnel was prepared anatomically through accessory medial portal, opened medially and distally. Reconstruction was performed using double loop hamstring tendon autograft. Femoral side was fixed using double cross pin, whereas tibial side was secured using single biodegradable interference screw and titanium staple. No external immobilization method such as brace was administered. Patients were encouraged to bear weight as tolerated. Standard physiotherapy was instructed to all patients postoperatively. All cases were evaluated clinically at the end of at least one year follow-up. Clinical and functional evaluation consisted of pivot shift and Lysholm, International Knee Documentation Committee (IKDC) scores and Tegner activity evaluation systems.Results:Mean age was 28.4 (18-39) years. Mean time between the injury and reconstruction was 13 (3-21) weeks. Average duration of surgery was 48 (35-70) minutes. No case of graft failure or posterior cortical fracture was encountered. In two cases, infection was treated successfully with local debridement and antibiotics with retention of the graft. At the end of follow-up period, none of the cases demonstrated positive pivot shift test. Pre-operative and follow-up Lysholm scores were 58.3±6.7 and 87.1±5.3 (p<0.001) respectively. Pre-operative IKDC scores were evaluated as C at 37 cases and D at 14, whereas, follow-up IKDC scores were evaluated as A at 42 cases, B at 8 and C at 1 case. Pre-operative and follow-up Tegner scores were 3.7±0.6 and 6.7±0.4 (p<0.001) respectively.Conclusion:Although fixation strength of transcondylar graft fixation techniques has been questioned over loop systems with cortical fixation, it was reported that transcondylar fixation causes less tunnel widening at long term. Our study revealed successful short term results, with femoral tunnel preparation using accessory medial portal and double cross pin femoral fixation, allowing early weight bearing and rehabilitation without graft and fixation failure.

Análise biomecânica da fixação tibial transversa na reconstrução do ligamento cruzado anterior

Objectiveto verify whether the combination of tibial cross pin fixation and femoral screw fixation presents biomechanical advantages when compared to femoral cross pin fixation and tibial screw fixation for the reconstruction of the anterior cruciate ligament (ACL). Methodsthirty‐eight porcine knees, and bovine extensor digitorum tendons, were used as the graft materials. The tests were performed in three groups: 1) standard, used fourteen knees, and the grafts were fixated with the combination of femoral cross pin and a tibial screw; 2) inverted, used fourteen knees with an inverted combination of tibial cross pin and a femoral screw; 3) control, ten control tests performed with intact ACL. After the grafts fixation, all the knees were subjected to tensile testing to determine yield strength and ultimate strength. Resultsthere was no statistically significant difference in survival techniques in regard to strength, yield load and tension. There was a higher survival compared in the standard curves of yield stress (p<0.05). Conclusionthere is no biomechanical advantage, observed in animal models testing, in the combination of tibial cross pin fixation and femoral screw when compared to femoral cross pin fixation and tibial screw.

Clinical and radiological outcome of Endobutton versus cross-pin femoral fixation in hamstring anterior cruciate ligament reconstruction

BackgroundThe selection of a graft and the method of graft fixation are critical in anterior cruciate ligament (ACL) reconstruction surgery. ACL reconstruction with the hamstring tendon provides sufficient strength for early rehabilitation and activity; the tendon to bone healing and the fixation method can become an issue with the hamstring tendon, which affects the functional outcome.Aim of the workThe aim of this study was to compare the clinical and radiological outcome of Endobutton femoral fixation and cross-pin femoral fixation for primary ACL reconstruction using quadrupled hamstring tendons with a minimum follow-up of 2 years.Type of studyRetrospective study.Patients and methodsForty-five patients were evaluated 2 years after arthroscopic ACL reconstruction. Two methods of graft fixation were compared: in group 1 (20 patients, EB group), an indirect graft fixation was achieved utilizing the Endobutton with a manually knotted polyester tape for proximal femoral fixation combined with bicortical suture and post-tibial fixation. In group 2 (25 patients, TF group), a direct graft fixation was achieved utilizing cross-pin femoral fixation (TransFix II Pin) with an additional autograft bone plug inserted into the femoral tunnel. Tibial fixation of the graft was performed with a bioabsorbable interference screw and an additional staple on the graft. All cases were operated using a transtibial technique.ResultsAccording to the IKDC evaluation form, the clinical outcome of the TF group was better than that of the EB group. Radiographs of the EB group showed a higher degree of divergence of the osteosclerotic lines indicating the bone tunnels in comparison with the TF group. The entrance diameters of the drilled femoral bone tunnels were 12.5 and 10.5 mm in the EB group and the TF group, respectively (P < 0.05).ConclusionWe conclude that avoiding tapes and sutures and using a surgical technique with direct graft fixation minimizes movement of the tendon graft for ACL reconstruction and improves the clinical results.

In vivo degradation characteristics of bioabsorbable cross-pins in anterior cruciate ligament reconstruction

BackgroundWe evaluated degradation of bioabsorbable femoral cross-pins following anterior cruciate ligament (ACL) reconstruction. MethodsFour patients underwent ACL reconstruction using hamstring autograft with femoral fixation provided by a polylactic acid/polyglycolic acid copolymer (LactoSorb L15) cross-pin. Serial computed tomography (CT) scans were performed of the reconstructed knees at approximately 6weeks, 4months, 1year and 2years, postoperatively. A radiologist evaluated the scans for density of pins and surrounding bone and pin morphology. ResultsThe cross-pins demonstrated a relative reduction in density of 7.7%, 49.1%, and 75.0% at 4months, 1year and 2years, respectively. Bone density values adjacent to the pin decreased by an mean of 8.6% between 6weeks and 4months. At one year an additional 14.2% reduction in bone density was seen but at 2years the relative reduction in bone density had decreased to 7.4%. Evaluation of pin morphology revealed that minimal change had occurred after 6weeks. At 4months all of the pins were showing some morphologic changes on the surface, but none had fractured. After 1year, two of the pins had fractured. By 2years all of the pins had fractured. None of the pins had completely reabsorbed at 2years postoperatively. ConclusionsLactoSorb L15 cross-pins for femoral fixation in ACL reconstruction remain largely unchanged 4months postoperatively, suggesting that this device maintains the necessary structural integrity to allow early integration of soft tissue grafts within bone tunnels. Level of evidenceIV, case series.

Improvement of primary stability in ACL reconstruction by mesh augmentation of an established method of free tendon graft fixation. A biomechanical study on a porcine model

PurposeThe aim of the present study was to compare primary stability in ACL reconstruction and ultimate load to failure of a mesh augmented hamstring tendon graft fixed with two cross pins to established hamstrings and bone-patellar-tendon-bone (BTB) graft fixation methods. MethodsForty fresh porcine femora were divided into four groups: (A): BTB graft fixed with two RigidFix® pins, (B): hamstring tendon graft fixed with a Milagro® interference screw, (C): hamstring tendon graft fixed with two RigidFix® pins, and (D): hamstring tendon graft augmented with Ultrapro® mesh fixed with two RigidFix® pins. Each graft underwent cyclic loading in tension and load to failure. Elastic and plastic displacements were measured by 3-dimensional digital image correlation. Groups were compared by one-way ANOVA and Tukey–Kramer post-hoc tests. ResultsAfter 1000cycles, the mean plastic displacement was lowest in the BTB graft (p<0.001). Plastic displacement was significantly lower in the mesh augmented group compared to the plain hamstring graft and the Milagro screw group (p<0.05). Load to failure was highest in the mesh-augmented group; significant to the hamstring tendon (p=0.023). ConclusionAlthough the BTB-graft represented the most stable construct against plastic displacement in our study, mesh augmentation of free tendon grafts significantly increased primary stability and reduced plastic displacement of femoral cross pin fixation. This new augmentation device may better protect the hamstrings graft from secondary elongation during postoperative rehabilitation. Clinical relevanceMesh augmentation seems to be an effective technique to stabilise free hamstring tendon autografts during postoperative rehabilitation with significant reduction of graft slippage.

Femoral Cross-Pin Breakage and Its Effects on the Results of Anterior Cruciate Ligament Reconstruction Using a Hamstring Autograft

The primary aim was to determine the rate and risk factors of double biodegradable femoral cross-pin breakage after anterior cruciate ligament reconstruction using a hamstring autograft. In addition, we compared clinical outcomes and magnetic resonance imaging (MRI) findings related to grafts for knees with and without a broken cross-pin. A retrospective review of 53 knees (53 patients) was performed. Cross-pin breakage was determined by follow-up MRI. Age, sex, weight, height, presence of a posterior transcortical cross-pin breach, time between surgery and follow-up MRI, graft diameter, and cross-pin position (superior or inferior) were included in the analysis. Differences in Lysholm knee scores, International Knee Documentation Committee grades, anterior laxity, and pivot-shift test results were examined in relation to cross-pin breakage. In addition, anterior cruciate ligament graft integrity and osseous graft integration by MRI were assessed and compared between knees with broken cross-pins and knees with intact cross-pins. A cross-pin was broken in 25 of 53 knees. A cross-pin posterior transcortical breach was the only factor found to be significantly correlated with cross-pin breakage (odds ratio, 6.117; P = .033) by univariate analysis. No significant differences in clinical outcomes were found to be related to cross-pin breakage, but femoral tunnel enlargement was more frequent in knees with breakage than in those without (P = .002). Breakage of biodegradable cross-pins used for femoral fixation is relatively common but did not affect clinical outcomes. However, femoral tunnel enlargement was found to be greater in knees with a broken cross-pin. The only significant relation found was between a cross-pin posterior transcortical breach and breakage, which suggests that pin breakage is related to a technical error. These findings should be borne in mind when a double biodegradable cross-pin is being considered for femoral fixation. Level IV, therapeutic case series.

Lateral meniscal tear resulting from the femoral cross-pin used for hamstring graft fixation in anterior cruciate ligament reconstruction

We report a case of lateral meniscal tear resulting from the femoral cross-pin used for hamstring graft fixation in anterior cruciate ligament (ACL) reconstruction. A 29year old man presented with symptoms of knee pain, catching and locking, 13months following an ACL reconstruction. Magnetic resonance imaging (MRI) and arthroscopy confirmed the broken femoral cross-pin abutting the lateral meniscus and the resulting meniscal tear. Removal of the broken femoral cross-pin and repair of the lateral meniscal tear resulted in resolution of symptoms. Distal femoral cross-pin fracture and its intra-articular position are postulated as the cause of this lateral meniscal tear. Hence, we recommend a low threshold to investigate with a MRI scan any new symptoms following ACL reconstruction with cross-pin fixation.

Influence of knee flexion and femoral cross-pin insertion angle on posterolateral structures of the knee and lateral fixation lengths during ACL reconstruction

Some studies have investigated knee flexion angle on the sagittal plane and insertion angle of the cross-pin on the coronal plane to evaluate proper femoral fixation. They evaluated the possibilities of injury to the posterolateral (PL) and neurovascular structures using several methods. The purposes of this study were to evaluate (1) the influence of knee flexion and femoral cross-pin insertion angles on knee PL structures and (2) the lateral fixation length of the cross-pin. Ten fresh cadaveric knees with no previous surgeries around the knee were used. Transtibial femoral tunnels (1:30 or 10:30 o'clock position) were made at three different knee flexion angles (70°, 90°, and 110°). Two cross-pin guidewires (superior and inferior pins) were drilled at three different insertion angles [downward 30°, 0° (parallel to floor line), and upward 30°] for each knee flexion position. The distances from the insertion point of the two cross-pins to the lateral collateral ligament (LCL) and popliteus tendon (PT), and the distance from the lateral wall of the femoral tunnel to the lateral cortex of the femoral condyle were measured. No significant differences were observed in the superior and inferior pin depths (p=0.56 and 0.39). The distances from the superior pin to the LCL and from the inferior pin to the LCL were significantly shorter in all knee flexions with 0° and an upward 30° insertion angle than with 70° and 90° knee flexion with a downward 30° insertion angle, respectively (superior pin: p=0.02 and 0.03; inferior pin: p=0.03 and 0.03). No significant difference was observed in the distance between the superior pin and inferior pins and the PT (p=0.25). The cross-pin was inserted close to the LCL and PT, and a downward 30° angle was the safest insertion angle. Lateral fixation length was sufficient for the cross-pin fixation in the 10:30- or 1:30-positioned femoral tunnel.

The risk of chondral injury during the Rigidfix femoral fixation via the anteromedial portal to reconstruct the anterior cruciate ligament

Objective To evaluate the risk of chondral injury during anterior cruciate ligament (ACL) reconstruction using a double cross-pin femoral fixation device via the anteromedial portal in Chinese cadavers. Methods Nine specimens of the knee (6 left ones and 3 right ones) were taken from 5 male and 4 female conservative cadavers of Chinese adult. The average age of the cadavers were 34.8 (26 to 45)years old. Femoral tunnel drilling and cross-pin guide insertion were performed using the Rigidfix Cross Pin device through the anteromedial portal. The ACL reconstructions were simulated at 3 entrance points of the cross-pin (0°, 45° and 90° relative to the horizontal plane) . The risks of chondral injury were statistically analyzed when the cross-pin entrance point was at the 3 different positions relative to the femoral chondral surface. Results The incidence of chondral injury was 100% when the Rigidfix cross-pin guide was at 90° relative to the horizontal plane. When the Rigidfix cross-pin guide was at 45° and 0° the incidences of chondral injury were 66. 7% and 22. 2% respectively. Conclusion Since there is always a risk of chondral injury when the Rigidfix cross-pin device is used to reconstruct ACL via the anteromedial portal, the anteromedial portal is not recommended for the ACL reconstruction using Rigidfix femoral fixation. Key words: Anterior cruciate ligament; Cartilage, articular; Anteromedial portal

MRI of broken bioabsorbable crosspin fixation in hamstring graft reconstruction of the anterior cruciate ligament

To report seven cases of broken bioabsorbable femoral crosspins identified by MRI in evaluation of hamstring grafts of the anterior cruciate ligament. Seven cases of broken bioabsorbable crosspins utilized in femoral fixation of ACL hamstring grafts were identified prospectively and retrospectively from our PACs database during a period from 9/1/08 to 8/31/09. All imaging was performed using 1.5 or 3.0 Tesla MRI and were evaluated for T2 signal within and surrounding the crosspin, osteolysis surrounding the fragments, displacement of fragments, and graft integrity. Time from surgery was also recorded. Seven cases of hamstring grafts with broken bioabsorbable crosspins were imaged 4months to 3years following grafting. There was osteolysis surrounding the crosspin in all but one case in which the graft was intact but a pin fragment was displaced into the joint. One graft failed due to aseptic foreign-body reaction to the fixation with aggressive osteolysis at 9months post surgery. In the remaining five, the ACL graft was either completely torn, partially torn, lax, or degenerative and frayed. Of these, the crosspins were broken and angulated with osteolysis surrounding the apex of the angulated fragment or demonstrated lateral extrusion of the peripheral fragment. Bioabsorbable crosspins utilized in femoral fixation of hamstring graft reconstruction of the ACL may become fractured. While the natural history of osteo-integration of these devices as demonstrated by MRI has not been defined, osteolysis surrounding the fragments, extrusion or displacement of the fragments, and graft laxity or failure would suggest that these are abnormal findings that should be reported.

Comparative outcome analysis of malpositioned and properly positioned fixation groups after hamstring autograft ACL reconstruction with femoral cross-pin fixation

Anterior cruciate ligament (ACL) reconstruction using soft tissue grafts has been gaining in popularity. Cross-pin fixation is used frequently, and its principle of fixation is an expansion mechanism. However, some malpositioned cases have been reported, and these malpositions may cause poor outcomes. Our aim was to compare the stability and clinical results between malpositioned and properly positioned cases. From November 2003 to December 2007, 41 patients were enrolled in this study. We divided these patients into malpositioned and properly positioned subgroups. The malpositioned group was defined by the presence of any finding among the following: posteriorly directed cross-pin to the posterior condylar line upon axial imaging, breakage upon coronal imaging, and outside-positioned cross-pin to the distal femoral posterior cortex upon sagittal imaging. We compared clinical and stability results between the two groups. Twenty-three patients were included in the properly positioned group, and 18 in the malpositioned group. The intra-class correlation coefficient for the intra- and inter-rater agreement ranged from 0.88 to 0.93 (0.88, 0.91, 0.91, and 0.93). No significant differences were found between the two groups in the stability assessment using a KT-2000 arthrometer and pivot-shift test ( P = 0.93 and 0.78, respectively). No significant differences were found between the two groups in the clinical knee scales ( Ps = 0.08-0.93). This study showed that some malpositions can occur with cross-pin femoral fixation. However, we obtained comparable good outcomes regardless of the fixation strategies if the initial fixation was correct.

Femoral Cross-Pin Safety in Anterior Cruciate Ligament Reconstruction as a Function of Femoral Tunnel Position and Insertion Angle

To compare femoral cross-pin guidewire insertion at differing angles to identify "safe zones" relative to saphenous nerve, popliteus tendon, fibular collateral ligament, peroneal nerve, and femoral artery/vein locations between transtibial and medial-portal femoral tunnel drilling methods. Five paired cadaveric knees were randomly assigned to a transtibial or medial-portal femoral (anatomic) tunnel drilling group. Guidewires were inserted at differing frontal plane angles (+10°, 0°, -10°, and -20°). Distances between the guidewire and the anatomic structure of interest were measured with an electronic caliper. Two-way analysis of variance showed that guidewire angle, not tunnel drilling method, created significant differences between guidewire-saphenous nerve (P < .001) and guidewire-femoral artery/vein (P < .001) distances. The +10° angle showed a shorter guidewire-saphenous nerve distance than the 0°, -10°, and -20° angles. The +10° angle also showed a shorter guidewire-femoral artery/vein distance than the -10° and -20° angles, and the 0° insertion angle created a shorter guidewire-femoral artery/vein distance than the -10° and -20° angles. Fisher exact tests showed that guidewires inserted at a +10° angle showed a greater incidence of safe-zone violations for the saphenous nerve (P = .04) and femoral artery/vein (P < .0001). Insertion angle, not tunnel drilling method, influenced saphenous nerve and femoral artery/vein injury risk. At the +10° angle, the saphenous nerve and femoral artery/vein are at greater risk for surgically induced injury. Guidewire insertion at -10° or -20° angles should increase concerns about potential popliteus tendon and fibular collateral ligament injury. Insertion angle, not tunnel drilling method, influenced saphenous nerve and femoral artery/vein injury risk.

Femoral Tunnel Widening after Quadrupled Hamstring Anterior Cruciate Ligament Reconstruction

To evaluate the extent of femoral tunnel widening after quadrupled hamstring anterior cruciate ligament reconstruction using femoral cross pin fixation in contrast to bioabsorbable screw fixation augmented with Endopearl. 16 patients underwent cross pin femoral fixation and the next 15 underwent bioabsorbable screw fixation augmented with Endopearl. The patients were evaluated radiographically for femoral tunnel widening. Standard posteroanterior radiographs of the knee in full extension were taken at postoperative year 2 and 5. The tunnel width was measured at the opening, the widest and the most proximal parts of the femoral tunnel. In the femoral cross pin and bioabsorbable screw fixations, the mean femoral tunnel sizes were 7.6 and 8.0 mm, respectively. The overall mean tunnel widening at all measured sites were 2.7 and 1.8 mm at the 2-year follow-up and were 2.5 and 1.8 mm at the 5-year follow-up, respectively. The femoral tunnel widening was greater in the cross pin than the bioabsorbable screw group, but only the difference in the most proximal part was significant (p=0.01 at year 2 and p<0.001 at year 5). Femoral tunnel widening was greater in femoral cross pin fixation, probably related to the windshield-wiper and bungee-cord effects. It usually occurred in the first 2 years after the operation and remained static thereafter.

Anterior Cruciate Ligament Reconstruction by Using Bioabsorbable Femoral Cross Pins: MR Imaging Findings at Follow-up and Comparison with Clinical Findings

To determine the frequency of imaging findings and complications related to bioabsorbable femoral cross pins at follow-up magnetic resonance (MR) imaging studies after anterior cruciate ligament (ACL) reconstruction and compare these MR imaging findings with clinical evaluation findings. The institutional review board approved this retrospective study, and informed consent was waived. Follow-up MR imaging studies (average, 26 months after surgery) in 218 patients with prior ACL reconstruction were retrospectively reviewed. Cross-pin fracture, posterior transcortical breach, migration, resorption, and lateral prominence of cross pins, as well as the cross-pin angle relative to the transepicondylar line, were investigated on MR images. The clinical evaluation included Lachman, anterior drawer, and pivot shift tests, as well as assessment for joint tenderness. Fracture, posterior transcortical breach, migration, and lateral prominence of cross pins were excluded from analysis when at least one cross pin was completely resorbed (n = 16 patients). Forty-five fractured cross pins were seen in 35 (17%) of 202 patients. The posterior femoral cortex was breached in 57 (28%) of 202 patients. Migration of fractured pin fragments occurred in 12 (6%) of 202 patients. There was a significant relationship between fractures and posterior breach of cross pins (P = .001), as well as between cross-pin angles and fractures (P = .002). Both cross pins were completely resorbed in 12 (6%) of 218 patients (average time since surgery, 53 months; range, 8-92 months). No significant association was found between any MR imaging finding related to cross pins and clinical test findings. Fracture and posterior transcortical breach of bioabsorbable femoral cross pins, commonly seen at follow-up MR imaging studies, do not correlate with clinical findings of joint instability or pain. Posteriorly angulated cross pins and posterior transcortical breach are significantly associated with cross-pin fractures.