Aims

The proximal tibia (PT) is the anatomical site most frequently affected by primary bone tumours after the distal femur. Reconstruction of the PT remains challenging because of the poor soft-tissue cover and the need to reconstruct the extensor mechanism. Reconstructive techniques include implantation of massive endoprosthesis (megaprosthesis), osteoarticular allografts (OAs), or allograft-prosthesis composites (APCs).

Modular endoprostheses are commonly used for reconstruction of proximal tibia defects after bone tumor resection and patellar tendon reattachment directly on the prosthesis represent an issue frequently ending in extension lag. Allograft-prosthesis composite implants theoretically provide the advantages of prosthetic implants (joint stability, mechanical resistance and long term durability) and the advantages of massive allograft reconstruction (bone stock mantainance and biologic reattachment of patellar tendon). From 1997 to 2007 19 patients (mean age: 39±16 years old) underwent proximal tibia oncologic intra-articular resection with wide margins. Primary diagnosis included giant cell tumor, osteosarcoma, chondrosarcoma and a failed osteoarticular allograft in 10, 4, 3 and 2 patients respectively. Tibial resection length was 10.4±3.4 cm in 18 knees. In one patient with chondrosarcoma the entire tibia was resected. Three patients received preoperative and postoperative chemotherapy, one only postoperative.

Reconstruction was performed with an allograft-prosthesis composite implant and direct suture of the host patellar tendon to the allograft one. Fresh frozen allograft and modular Link prosthesis were used for reconstruction. Five to six weeks of knee immobilization in extension followed the operation. A transient peroneal nerve palsy was observed in three patients. Two patients with a stiff knee underwent an open release after less than one year from index surgery. One patient had a local recurrence from osteosarcoma and underwent an above knee amputation. No patient developed distant metastasis at follow-up.

After 59±37 months none of the patients had implant revision for mechanical complications. One patient had 2-stage implant revision for deep infection. A minor allograft resorption with aseptic drain was observed in one patient who underwent surgical debridement. One other patient had a moderate allograft resorption. Knee flexion was 96±12 degrees. All the patients but two could reach complete knee extension and only two had a minor extensor lag (less than 15 degrees).

In conclusion intrarticular tibia resection and allograft-prosthesis composite replacement ensures satisfactory oncologic and functional results at a mid-term follow-up.

Knee extensor mechanism reconstruction after excision for bone or soft tissue tumors is a challenging procedure. When a resection of the patellar bone-tendon apparatus is required, an omologous graft can be used for its reconstruction to avoid knee arthrodesis and preserve a functional knee. Since 1996 we performed such a procedure in 15 cases in 14 patients. In 4 cases (Group 1) excision and reconstruction involved only the patella and the attached tendons together with the involved soft tissues. In the remaining 11 cases (Group 2) an extrarticular en-bloc knee resection was accomplished and reconstruction was obtained by a megaprosthesis to replace the distal femur and a composite allograft-prosthesis to replace proximal tibia and the extensor apparatus. One of the en-bloc knee resections was performed in a patient who had previously had an isolated extensor apparatus replacement, which was later converted to a complete knee resection and substitution after a local relapse.

A free flap (anterolateral thigh) was used in 4 patients.

Histotypes were as follows:

Group 1: pleomorphic sarcoma 2, synovial sarcoma 1, myxofibrosarcoma 1.

One patient in group 2 was lost at follow-up after a few months. In the remaining patients follow-up ranged from 7 to 132 months.

In Group 1 two local and one distant (groin lymphnodes in one of the two patients affected by local recurrence) relapses occurred, in Group 2 one local and 4 distant relapses (lung) occurred. One of these latter distant relapses affected the patient at the beginning in Group 1 and later converted to Group 2.

Besides recurrences, 4 patients in Group 2 were affected by local complications:

one deep infection;

Active extension was initially obtained in all patients and, when local complications did not occur, it was stable with time. Extension lag ranged from 0 to 30°. Maximum flexion ranged from 80 to 110°. Patients could walk without brace nor aids.

Allograft reconstruction after extensor apparatus excision, either alone or combined to a total knee resection, can be an efficacious option in the treatment of sarcomas of the knee.

Proximal tibia reconstruction after oncologic resection is challenging due to bone stock and extensor mechanism restoration.

From 1997 to 2007 19 patients (mean age: 39±16 years old) underwent proximal tibia oncologic intra-articular resection with wide margins. Primary diagnosis included giant cell tumor, osteosarcoma, chondrosarcoma and a failed osteoarticular allograft in 10, 4, 3 and 2 patients respectively. Tibial resection length was 10.4±3.4 cm in 18 knees. In one patient with chondrosarcoma the entire tibia was resected. Three patients received preoperative and postoperative chemotherapy, one only postoperative.

Reconstruction was performed with an allograft-prosthesis composite implant and direct suture of the host patellar tendon to the allograft one. Fresh frozen allograft and modular Link prosthesis were used for reconstruction. Five to six weeks of knee immobilization in extension followed the operation. A transient peroneal nerve palsy was observed in three patients. Two patients with a stiff knee underwent an open release after less than one year from index surgery. One patient had a local recurrence from osteosarcoma and underwent an above knee amputation. No patient developed distant metastasis at follow-up.

After 59±37 months none of the patients had implant revision for mechanical complications. One patient had 2-stage implant revision for deep infection. A minor allograft resorption with aseptic drain was observed in one patient who underwent surgical debridement. One other patient had a moderate allograft resorption. Knee flexion was 96±12 degrees. All the patients but two could reach complete knee extension and only two had a minor extensor lag (less than 15 degrees).

In conclusion intrarticular tibia resection and allograft-prosthesis composite replacement ensures satisfactory oncologic and functional results at a midterm follow-up.

Introduction : The purpose of the study is to compare in a randomised clinical double blind trial two methods of hamstring ACL reconstruction, the SIngle Bundle (SB) and the Double Bundle (DB).

Materials and methods: Seventy patients, with a chronic ACL insufficiency, were randomized to receive a unilateral single or double bundle ACL reconstruction. All the operations were performed by the same surgeon using the same two incision outside-in technique. The tibial guide wire was introduced with a 65 degrees Howell guide in extension to avoid impingment. To introduce the second tibial wire (posterolateral wire) a prototype guide that lets you place the wire with a fixed angulation and a fixed distance (9 mm) from the first was used. On the femoral side we used a modified Rear Entry guide. In a SB reconstruction the 10.00 o’clock position (right knee), intermediate between the two anatomic bundles, was used. In a DB reconstruction the first wire was placed in the anteromedial insertion area, close to the “over the top” position on the lateral wall and for the second wire the same prototype guide that gives you the correct angulation and distance with the first (10 mm) was used. The direction was chosen in order to exit 5 mm close to the posterior cartilage. The graft was prepared and pretensioned as to have two arms of the same diameter. It was fixed on the cortex of the tibia by means of a titanium ring bridge when doing a SB and looped around a cortical bony bridge when doing a DB. Tensioning and femoral fixation of the SB was done at 20 degrees, while in the DB tensioning and fixation of the PL bundle was achieved first after cycling at 10–15 degrees and of the AM bundle at 40–45 degrees. Femoral fixation was obtained via RCI titanium interference screws and one additional cortical titanium staple. The same moderately aggressive rehabilitation was utilized in both groups. Outcome assessment was performed by an indipendent observer, blinded to the involved leg and type of reconstruction, using the new IKDC form, the KOOS score, the KT-1000 arthrometer.

Results: All patients reached a minimum follow-up of one year. No difference was found in terms of overall KOOS and IKDC subjective scores. A significant difference was found (p< .001) in KT data and in IKDC final ojective scores (Excellent-A-result: 73% SB and 95% DB). he DB group showed a tred to less pivot shift (glide).

Conclusion: In the short period the DB reconstruction offered better knee stability and better objective results than the 10.00 o’clock SB. Longer follow up and accurate instrumented in vivo rotational stability assessment is probably needed to further disclose small but important differences.

Background and purpose of the study: the anterior cruciate ligament (ACL) is a continuum of fibres which are differently recruited through range of motion. Two main functional bundles can be identified: the postero-lateral bundle (PLB) which is taut exclusively towards extension and the anteromedial bundle (AMB) which is taut through full range of motion. The purpose of this investigation was to assess the relative contribution of the bundles to intact knee kinematics.

Material and methods: fourteen intact cadaver knees were instrumented in a non-ferromagnetic rig and six degrees of freedom kinematics through flexion-extension was recorded with an electromagnetic device under the application of a 90N anterior force or a 5Nm internal rotation torque. The AMB and PLB were alternatively cut first in each knee and knee kinematics was recorded. The other bundle was then dissected and ACL deficient knee kinematics tested.

Results: when the AMB was cut anterior tibial translation increased and no effects on rotations were recorded. When the PLB was first cut no significant effects on anterior laxity were observed. Different rotational responses were observed in different knees. After the section of both bundles a larger increase in anterior laxity was observed. The changes in rotation differed from knee to knee.

Discussion: The AMB is a primary restraint against anterior tibial translation and has a small and variable effect on rotations. The PLB is a secondary restraint against anterior tibial translation in extension and maintains normal rotational laxity in AMB deficient knees. Therefore, reconstruction of both bundles is theoretically advantageous to restore both intact knee anteroposte-rior and rotational laxity.

Static finite-element (FE) analysis has been extensively used to examine polyethylene stresses in Total Knee Arthroplasty (TKA). The aim of this study was to use an explicit-dynamic FE approach with force driven models to simulate both the kinematics and the internal stresses within a single analysis of the Meniscal Bearing Knee (MBK, Zimmer, Warsaw, IN) prosthesis

The MBK is a mobile-bearing prosthesis (rotating and AP-gliding) with complete femorotibial conformity throughout motion owing to spherical femoral condyles. The FE meshes of the MBK were created from data obtained from the manufacturer as Initial Graphics Exchange Specification (IGES) files. Three-dimensional FE models of the original MBK design and of two modified versions (MBK-Flex and MBK-PS) were generated in Hypermesh 5.1 software. The tibial insert was modeled as a flexible body with 82212 noded solid tetrahedral elements (Poisson ratio: 0.46). The femoral and tibial components were modeled as rigid bodies. No abnormal alignment or soft tissue imbalance were assumed. Linear soft tissue constraints (30 N/mm AP and 0.6 N-m/degree rotational displacements) were included. Axial load was 4.9mm medially displaced to achieve amedially-biased (60–40) condylar load allocation. Waveforms to simulate gait, stair-climbing and deep-knee-bending with the FE models were obtained from the proposed International Standards Organization 14243–1 and from literature data.

Peak contact stresses for each activity evaluated were below 11 MPa for both the original and modified MBK versions. Kinematics analysis showed similar amount of displacements (average rotations: 3.7°: average AP-glide: 2.5mm) for the various design during gait. In simulated stair-climbing and deep-knee-bending the PS version showed a more reproducible pattern of posterior rollback in flexion without increasing contact stresses.

Explicit FE analysis is an efficient screening tool before in-vivo or in-vitro testing. It provides a means of testing the effect of variables such as change in prosthetic design, surgical techniques and applied loads on knee forces and kinematics.

Objective: To compare double bundle ACL reconstruction kinematics to single bundle reconstruction, intact knee and ACL deficient knee employing an electromagnetic device in six cadaver knees under different antero-posterior and rotational loading conditions.

Methods: All the tests were performed with an intact ACL, with a deficient ACL and after single and double bundle ACL reconstruction.

In double bundle ACL reconstruction two tibial tunnels were drilled: for the anteromedial the 65 degrees Howell guide was employed; the posterolaetral was drilled through a prototype jig attached to the first guide. Two femoral tunnels were drilled outside-in with the Rear Entry guide. A 6 millimetres bovine tendon graft was employed and fixed to bone with interference screws.

Results: Posterior drawer loading conditions did not show differences between intact knee, single and double ACL reconstruction independently from rotational stresses.

Under an anterior drawer test double bundle ACL reconstruction restored anteroposterior laxity significantly better than single bundle reconstruction at 20 and 40 degrees of flexion. A trend towards a better rotational control of double bundle reconstruction was observed in extension.

Thirty patients with chronic lesions of the ACL underwent reconstruction of the ACL with double bundle technique. A wire at 65° was used for AM tibial tunnel and a prototype was used for the PL. For femoral tunnels, a transtibial technique was applied in fifteen patients and the outside-in technique was used in fifteen more. All patients had an MRI after three months. The tunnels position was studied with Amis’ circle method, as a proportion of the circle’s height and width. We compared the proportion of the anatomical data on fourteen cadaveric knees. In the transtibial group the AM tunnel was at 56% of the circle’s height and at 65%of the depth (mean); the PL was at 40% of the circle’s height and 54% of the depth. In the out-side group the AM tunnel was 48%of the circle’s height and at 66% of the depth; the PL one was at 32%of the circle’s height and at 61%of the depth. In corpses the AM insertion was at 50% of the circle’s height and 69% of the depth (mean). In conclusion the outside-in technique allows better anatomical positioning.

Purpose: Prospectively compare 3 different techniques of ACL reconstruction with autologous hamstrings graft.

Material and methods: 3 comparable groups of 25 knees each were selected. An arthroscopic single incision reconstruction was performed in all groups. In group A, a single bundle graft was inserted. In group B a double bundle reconstruction was performed with 1 tibial and 2 femoral tunnels. In group C, 2 tibial and 2 femoral tunnels were drilled. Fixation was achieved in all knees with Endobutton CL proximally and Washerloc screw distally. Outcome assessment was performed at 4 and 12 months postoperatively by an independent observer, using new IKDC evaluation form, the KT-1000 arthrom-eter, and a radiographic investigation.

Results: At 12 months FU the subjective score was 81 in group A, 76 in group B, and 89 in group C. The final IKDC score was satisfactory (A+B) in over 90% of the patients. The KT-1000 anterior tibial translation was 2.3, 2.5 and 1.9 mm in group A, B, and C respectively. The radiographic study showed no differences between the 3 groups in terms of incidence of tunnel widening.

Conclusions: At a minimum FU of 1 year we could not show a statistically advantage of the two bundle compared to the single bundle.

In the last few years the number of women who practise sport activities has substantially increased and this has led to an increase in the incidence of ACL tear in females. The aim of this study is to assess outcome differences at a minimum 3-year follow-up after ACL reconstruction in women using either a patellar tendon (BPTB) or a quadrupled-looped hamstring (DSTG) autograft fixed with modern devices.

Fifty women with a chronic, isolated ACL tear were randomised to receive a DSTG or BPTB graft for ACL reconstruction. Both groups were comparable as to age, injury-surgery, activity level, meniscal tears, surgical technique and reabilitation. All patients were prospectively evaluated by an independent observer using the IKDC form, the FKSAKP Score, the KT-1000 arthrometer and the Cybex NORM dynamometer. A radiographic study was performed to investigate tunnel widening.

All but two patients were satisfied with the reconstruction. The average side-to-side difference in anterior tibial translation was 2.4 mm in the BPTB group and 2.5 mm in the DSTG group. The final result was A (normal knee) in 56% and in 60% of the BPTB and the DSTG knees, respectively. A failure (4%) was present in each group. Muscle strength deficits at 60°/s, 120°/s and 180°/s were within 10% for extensors and within 5% for flex-ors in both groups. No statistically significant differences were found in terms of subjective satisfaction, objective evaluation, knee stability and muscle strength recovery. The BPTB group showed a higher incidence of postoperative kneeling discomfort (p< 0.05) and a larger area of decreased skin sensitivity (p< 0.001). The DSTG group showed a higher incidence of femoral tunnel widening (p=0.02).

Using strong and stiff fixation devices, ACL reconstruction in women is not influenced by the graft choice.