Introduction

Hallux Rigidus affects 2–10% of population, usually treated with cheilectomy or arthrodesis, however, for the subclass of patients who refuse to undergo fusion, Arthroplasty is an alternative solution, it maintain some degree of motion and provide pain relief. Toefit; is one of the prostheses being used. It is a total joint replacement with polyethylene insert.

The aim of this study is to find clinical and radiological outcomes of Toefit arthroplasty.

The first MTP Joint (MTPJ) is critical in normal gait. MTPJ replacements treat the articular surface as a hemisphere, as it appears radiographically. In reality the articular surface has two grooves to accommodate sesamoids and facilitate a better range of motion. We compare a standard hemispherical and a modified grooved implant. Six cadaver feet were implanted with Toefit 1st MTPJ replacements and sequentially four different metatarsal head implants. Two of the metatarsal heads had grooves. The intact joints were used as a baseline for comparison, with their measurements taken before implantation. Each construct had a standard dorsiflexion force applied (50N).

Flexion angle was measured on lateral radiographs. Contact pressure and area were measured with a pressure transducer (Tekscan I-Scan 6900 electronic pressure sensor).

The anatomical (grooved) implants showed higher flexion angles and lower contact pressures in each case although there were too few trials to reach statistical significance.

Results suggest a tendency towards better flexion and contact pressure characteristics in a more anatomical device. This may lead to better clinical outcomes for 1st MTPJ replacements.

Introduction: Drilling of the femoral bone tunnel in anterior cruciate ligament reconstruction may be performed in a transtibial drilling technique or via the anteromedial portal.

Purpose: To determine the accuracy of the radiographic bone tunnel position using either a transtibial or anteromedial drilling technique.

Materials & methods: The postoperative lateral radiographs of 100 patients after anterior cruciate ligament reconstruction were reviewed. In each patient, the femoral bone tunnel was created either through the tibial tunnel or via the anteromedial standard arthroscopy portal. The resulting position of the femoral tunnel was evaluated according to reference values reported by Aglietti (65 % of the cortical femoral A-P distance along Blumenstaat’s line), Amis (60 % of the A-P diameter of the posterior lateral femoral condyle parallel to Blumensaat’s line), and Harner (80 % of the A-P length of Blumensaat’s line). The mean deviation of the radiographic tunnel position from the referenced values was statistically evaluated.

Results: Radiographic bone tunnel positions with transtibial drilling were 62.42 ± 8.36, %, 54.53 ± 8.43 %, and 75.84 ± 9.56 % according to Aglietti, Amis, and Harner, respectively. Bone tunnel positions with anteromedial drilling were 65.46 ± 5.29 %, 59.59 ± 4.18 %, and 79.93 ± 4.24 %, respectively. The mean deviation from the reference values was significantly higher when comparing transtibial to anteromedial drilling. Transtibial drilling resulted in a significantly more anterior bone tunnel position.

Conclusion: Precise bone tunnel placement is a prerequisite for proper postoperative knee function and stability. The results of this study indicate that the accuracy of femoral bone tunnel placement through the anteromedial arthroscopy portal was superior to transtibial drilling. It may therefrore be concluded that drilling the femoral tunnel through the anteromedial portal is recommended when using fixation techniques not depending upon placement of a transtibial guide.

Introduction: Computer-assisted minimal invasive total knee arthroplasty (MIS-TKA) provides the patient with the advantages of computer navigated total knee arthroplasty (CN-TKA) and early mobilization and progressive rehabilitation because of minor soft tissue injury. Since conventional landmarks are not visible for the surgeon throughout the operation, he must rely on the data displayed by the computer navigation system. This study was designed to assure that MIS-TKA reveals identical mechanical accuracy as conventional computer navigated TKA while reducing rehabilitation time.

Materials and methods: The Stryker knee navigation system was used intraoperatively. There were forty patients included in this study: 20 consecutive patients received computer navigated TKA (Scorpio) and 20 consecutive patients received MIS-TKA (Stryker-MIS Scorpio). Preoperatively and 6 months after the operation all patients received orthoradiograms and a CT-scan of the knee to determine mechanical and rotational alignment. Intraoperatively data shown by the navigation system was recorded. The HSS knee score was recorded preoperatively and 6 months postoperatively. Length of skin incision, length of hospital stay and postoperative range of motion were also determined.

Results: Analysis showed that the mechanical axis improved in both groups to less than 1° of varus. Rotational alignment of the femoral component showed reproducible values of less than 2° of rotation without significant differences between the two groups. Also, ligament laxity was almost identical preoperatively and postoperatively in 0°, 45° and 90° of knee flexion. Length of skin incision was significantly shorter in MIS-TKA. HSS knee score improved from a mean of 76 points (range 57–96) preoperatively to a mean of 92 points (range 64–100) 6 months postoperatively for both groups. Patients from the MIS-TKA group revealed a quicker recovery time than patients from the CN-TKA group. ROM improved sooner after the operation in the MIS-TKA group, however after 6 months both systems reached the same ROM. The length of hospital stay was significantly reduced by the MIS-TKA group.

Discussion: The Stryker knee navigation system aids the surgeon to precisely optimize mechanical and rotational alignment and to avoid malrotation and axial malalignment not only in CN-TKA but also in MIS-TKA. We have found no significant differences in preoperative and postoperative ligament laxity between the two groups. The advantages of minimal soft tissue damage in MIS-TKA can be achieved without loss of accuracy and with a great benefit for the patient.

Introduction: Computer navigation in total knee arthroplasty (TKA) may assist the surgeon with precise information about ligament tension and varus/valgus alignment throughout the complete range of motion, but there is only little information about how much ligament laxity is needed and how much laxity is too much. In the current study we measured the mechanical axis and opening of the joint at different time points, in different degrees of knee flexion and with varus and valgus stress during the procedure of computer navigated TKA.

Methods: Forty-nine consecutive patients underwent a MIS computer navigated TKA. With the Stryker Knee Navigation System varus/valgus alignment and distraction/compression was measured in 0°, 45° and 90° of knee flexion immediate after digitalization of the knee and after fascial closure. Values were noted in a neutral position and with maximal varus and maximal valgus stress applied. Patients with posterior stabilized implants were compared to those with cruciate retaining implants. Patients with preoperative varus malalignment or valgus malalignment were compared to patients with straight preoperative mechanical axes.

Results: At the beginning of the operative procedure the mean mechanical alignment was 1.9° varus at 0° knee flexion, 1.5° varus at 45° knee flexion and 1.5° varus at 90° knee flexion. Patients showed a mean mediolateral joint opening of 6.1° at 0° knee flexion, 5.9° at 45° knee flexion and 4.5° at 90° knee flexion. After implantation of the knee prosthesis and fascial closure mechanical alignment was 0.3° varus at 0° knee flexion, 0° varus at 45° knee flexion and 0.2° varus at 90° knee flexion. Mean joint laxity was 3.4° at 0° knee flexion, 3.1° at 45° knee flexion and 2.3° at 90° knee flexion. There was more lateral than medial joint opening postoperatively in 45° and 90° knee flexion regardless of the prosthesis type implanted. Preoperative varus and valgus malalignment could be reduced to values identical with those patients with straight preoperative mechanical axes.

Discussion: Mean varus/valgus laxity after implantation of a MIS computer navigated TKA was lower than prior to prosthesis implantation. Varus/valgus laxity of an approximate total range of 1.5°–2° can be achieved at all measured degrees of knee flexion and seems to be the ideal laxity for TKA. Computer navigation in TKA can consistently reduce preoperative varus/valgus malalignment to a level comparable to patients with preoperatively normal mechanical axes. More lateral joint opening is found before as well as after implantation of the prosthesis in 45° and 90° of knee flexion. The type of prosthesis implanted seems not to effect postoperative joint laxity.

Introduction: One of the four pillars of successful total knee arthroplasty (TKA) is restoration of the joint line. In conventional TKA the surgeon does not have a tool to control the accuracy of joint line restoration intraoperatively. The present study investigates if the preoperative joint line can be restored using an optical navigation system for TKA.

Materials and methods: Patients from two Orthopedic Centers (Istituto Orthopedico Rizzoli Bologna, 51 patients; Orthopädie Samedan, 42 patients) received computer assisted TKA (Stryker Scorpio) using the Stryker Knee navigation system. Using the software delivered with the navigation system depth of femoral and tibial medial and lateral osteotomies were recorded. After definite prosthesis implantation medial and lateral femoral condyle height as well as tibial length including polyethylene inlay were also recorded. Varus/valgus alignment was additionally recorded before and after prosthesis implantation.

Results: After femoral osteotomie varus/valgus alignment was 0 degrees (Stdv. 0.6 degrees). Lateral and medial osteotomies were performed with a depth of 8.2 and 8.8 mm respectively. Tibial osteotomie was performed with 0 degrees of varus/valgus (stdv. 0.7 degrees). Lateral and medial tibial osteotomies were performed with a depth of 7.5 and 4.8 mm respectively. After definite prosthesis implantation femoral and tibial varus/valgus alignment was 0.2 degrees of varus (stdv. 0.8 degrees) and 0.1 degrees of varus (stdv. 0.8 degrees) respectively. The femur was lengthened by 0.2 mm (stdy. 3 mm) medially and 1.1 mm (stdy. 3.1 mm) laterally. The tibia was shortened after component implantation by 1.5 mm (stdy. 3.4 mm) medially and 1.1 mm (stdv 3.1 mm) laterally.

Discussion: With the use of the Stryker Knee Navigation System, we can reconstruct the preoperative joint line with reproducible accuracy after a TKA. When prosthesis component and polyethylene inlay thickness are known, osteotomies may be performed and corrected intraoperatively to restore the joint line.

Press-fit fixation technique in anterior cruciate ligament (ACL) reconstruction has recently gained popularity. The objective of this study was to evaluate the initial fixation strength of human patellar tendon-bone (PTB) grafts with respect to bone-plug length and loading angle by using a femoral press-fit fixation technique.

Fourty-eight human PTB-grafts were obtained from 24 fresh frozen cadavers (mean age 72 years). The specimens were randomly assigned to two experimental groups: One with a 15 mm (n=24) and a second with a 25 mm patellar bone plug (n=24). The grafts were implanted to porcine femora in a press-fit fixation technique. Ultimate failure loads were measured at 10 mm/s at varying loading angles of 0, 30 and 60.

Biomechanical testing showed a significant difference of ultimate failure load comparing 15 mm (mean 236 N) to 25 mm (mean 333 N) bone plugs (p=0.015). In both groups, the fixation strength increased with rising loading angles. While axial graft loading exclusively caused plug dislocation, the predominant mode of failure was tendon rupture at 60 loading angle.

It is concluded that bone plug length and loading angle significantly influence the primary stability of PTB press-fit fixation in ACL reconstruction. Based on these findings, we recommend the use of patellar bone plugs with a minimum of 25 mm in length. If graft harvesting occasionally generates a patellar bone plug measuring 15 mm, restrictive postoperative rehabilitation should be advised.

Aims: The purpose of this study was to verify a partial bursal-side rupture of the rotator cuff (RC) using different imaging techniques with special emphasis on the validity of a specific method of subacromial arthrography (SAA). Methods: Patients (n=92, age 53.8 years) with a subacromial impingement syndrome underwent sonography, magnetic resonance imaging (MRI), and SAA. All diagnostic results were controlled by subsequent arthroscopic surgery. Results: Out of 31 surgically verified ruptures, 17 cases showed a partial rupture located towards the bursa. These had been detected by MRI and ultrasound with a sensitivity of 64% and 41%, respectively, while SAA as a diagnostic tool yielded a sensitivity of 82%. In 14 cases of complete RC ruptures, all imaging techniques had a similar sensitivity of 86 to 93%. Conclusions: It appears that SAA is a sufficient and valid diagnostic tool for the detection of partial bursa-sided RC ruptures. Ultrasound and MRI showed a comparably lower sensitivity. It is therefore concluded that SAA has clear advantages in the diagnosis of this defect with the consequence that open surgical techniques to the patient can be avoided.

Aims: The present experimental study raised the question whether corticosteroid therapy inßuences the sensitivity of the femoral head circulation to ischemia induced by hip joint tamponade. Methods: 31 Landrace pigs were treated in 4 groups. 12 animals received a 14 day methylprednisolone intramuscular application before hip joint tamponade. 11 pigs underwent hip joint tamponade without previous medication. Control groups comprised 4 animals not undergoing hip joint tamponade. Blood ßow measurement was undertaken in predeþned regions by radioactive microsphere technique. Results: Epiphyseal blood ßow decreased signiþcantly during hip joint tamponade. Reperfusion occurred to a level not signiþcantly differing from that before ischemia, whereas epiphyses remained ischemic in 2 pigs. In the steroid treated animals, the basic blood ßow appeared 2–3 times lower than that of the non medicated pigs. Also in the steroid group 2 epiphyseal remained ischemic. The metaphyseal corticalis in the steroid treated animals revealed signiþcant hyperperfusion. Conclusions: Ischemia by hip joint tamponade in a porcine model was produced quantitatively for the þrst time. The majority of femoral head epiphyses was reperfused on steady state blood ßow level. Nonreperfusion of 2 epiphyses in each group indicated that 6 hours of ischemia might be just below the minimum stress in order to produce necrosis of the femoral head. High dose steroid medication reduced the steady state blood ßow level of the femoral head 2–3 times but did not inhibit or disturb reperfusion.

Aims: Aim of this study was to asses the glenohumeral joint internal and external range of motion using ultra-sonographic based kinematic measurement. Methods: 27 male professional tennis players were bilaterally measured for internal and external rotation at 90 degrees of shoulder abduction while negating scapulothoracic motion. The normal control group consisted of 20 asymptomatic volunteers. Results: Both arms had signiþcantly greater degrees of external rotation than internal rotation (p< 0,05). The dominant arm (playing arm) had signiþcantly greater range of external rotation than the nondominant arm (p< 0,01). Analysis of internal rotational deþciency showed highly decreased internal rotation on the dominant arm (p< 0,01). The total rotational range of motion of the dominant arm was also found signiþcantly less (p< 0,01) in the elite tennis players. No signiþcant difference was found for the dominant and nondominant extremity in the control group. Conclusions: The objective measurement of glenohumeral rotational abilities has clinical application for the development of a speciþc treatment protocol that may reduce the risk of shoulder injury.

Aims: The present experiment addressed the question whether lipopolysaccharides (LPS), hip joint tamponade or their combination modulate hip perfusion. Methods: 16 immature Danish Landrace pigs of both genders were treated in 3 groups. 4 animals received LPS from escherichia coli intravenously 4 hours previous to hip joint tamponade. 8 pigs underwent the hip operation without previous medication. 4 animals without treatment served as control group. Blood ßow measurement was done by the Radioactive Tracer Microspheres technique. Results: Femoral head epiphyseal blood ßow decreased signiþcantly during hip joint tamponade. Reperfusion occurred to a level not signiþcantly differing from that before ischemia, whereas epiphyses remained ischemic in 2 pigs. The hip joint capsule showed signiþcant hyperperfusion during and after joint tamponade. No signiþcant difference was revealed comparing the LPS-treated and non-treated groups of pigs in all hip regions (p = 0.79, U-test). In addition, in the LPS-group, none of the femoral head epiphyses remained ischemic. Conclusions: LPS and hip joint tamponade, which have separately been discussed as pathomechanic factors of Non Traumatic Femoral Head Necrosis, have been combined in a bifactorial porcine model. Systemic lipopolysacchrides as bacterial endotoxin have no acute effect on regional hip perfusion which would make a consequent osteonecrosis probable. 6hourly hip joint tamponade alone evoked non reperfusion in 2 out of 8 pigs and a prolongation of the 6 hours ischemia might evoke more cases of non reperfusion.

Aims: The pathomechanism of avascular necrosis of the femoral head (AVN) is still debated. Hip joint synovitis and effusion may impair blood ßow to the femoral head. The critical ischemia time is around 6 hours, but repeated ischemic episodes may impair reperfusion and elicit AVN. The aims of this study were to investigate the value of dynamic MRI in femoral head after ischemia and during reperfusion. Methods: In 15 domestic pigs, 3–4 months old, femoral head ischemia was achieved by raising the joint pressure to 250 mmHg by dextran infusion through a hole in the acetabular wall. MRI was performed (Philips gyroscan S15, 1.5 T, Gd-DTPA enhancement, dynamic imaging interval 39 sec.) before ischemia, after 6 hours of ischemia, and again after 4 hours of reperfusion. Results: Signal intensity versus time (SI/t) plots were constructed from 347 MR studies. By regression analysis of SI/t curves an index (enhancement/decrease) was developed as criterion for arterial or venous circulatory disturbance. Index values < 1.1 signiþed arterial impairment, > 100 venous disturbance. Values between 1.1 and 100 were considered normal. The positive predictive value for disturbed osseous blood ßow was 96%. Conclusions: Early detection of intraosseous circulatory disturbance was possible with a mathematical model for dynamic MRI results. The method is reproducible and may be employed in the early diagnosis of AVN and during treatment for monitoration of revascularisation.

Aims: Increased intraarticular hip joint pressure has been considered a pathomechanism in femoral head necrosis. The aim of this study was to investigate histopathological femoral head changes in an immature big animal model of arterial hip joint tamponade. Methods: Out of a total of 15 domestic pigs, 11 animals were randomly chosen to undergo 6h unilateral hip joint tamponade at an intraarticular pressure of 250mmHg while 4 animals underwent a unilateral sham operation serving as controls. 4h after the end of hip joint tamponade, the animals were killed with potassium chloride, the femoral heads were excised, and þxed in Schafferñs solution for undecalciþed Goldnerñs, alcianblue-PAS, Krutsay, methyl green pyronine, toluidin blue O, and standard Giemsa staining. Results: A great number of congested sinus and vessels of the terminal vascular system showed inclusions of blood cells dominantly in the tamponaded hip side. Congestion also be documented by dilated sinus with deformed blood cells. Bone remodeling of normal osteoblast and osteoclastic lacuna activity was noted in all trabeculae. None of the known signs of osteonecrosis were found. Conclusions: Our acute histological study in immature pigs shows the early microcirculatory disturbances which may precede femoral head necrosis. Future research is needed to investigate histologic changes after a longer time interval following hip joint tamponade, and into the duration of the joint tamponade.

The role of the subtalar joint in patients with chronic hindfoot instability remains controversial We have made an attempt at quantifying subtalar instability clinically and comparing this with findings at dynamic ultrasound. As a result of this study we have been able to demonstrate and test for reliability a new ultrasound sign for calcaneofibular ligament (CFL) deficiency.

A preliminary dissection of four cadavers was undertaken to determine the role of the CFL in providing subtalar stability and the effect of sectioning this ligament. Fifteen patients with symptomatic hindfoot instability were examined by two orthopaedic surgeons and subsequently had dynamic ultrasound examination of their ankle and subtalar joints on both the affected and unaffected sides. Ten control ankles were also examined. It was found that in a subset of these, with positive clinical signs of subtalar instability, the CFL failed to elevate the overlying peroneal tendons and alter their roundness on ultrasound cross section (suggesting that the CFL was deficient) whilst in normal hindfeet and those without a positive clinical test for subtalar instability the tendons were elevated in a reproducible manner. There was perfect correlation with the findings (in terms of the presence or absence of the CFL) at surgery in 5 patients undergoing lateral stabilisation procedures.

We believe this new sign is reliable and demonstrates the integrity of the CFL in patients with chronic hind-foot instability.

Aim of study

The thrust plate prosthesis is an implantat with metaphyseal fixation at the proximal femur, which leaves the diaphyseal bone untouched. Therefore this implant preferably is employed in younger patients. It is dependent on a good bone quality in the proximal femur. Because bone quality is reduced in patients with polyarthritis, this kind of endoprosthesis may have a higher failer rate than conventional stemmed endoprostheses in these patients. Therefore in patients with polyarthritis even short- end midterm results of the thrust plate prosthesis should be analyzed.

Material and Methods

47 thrust plate prostheses were implanted in 42 patients with polyarthritis (29 with rheumatoid arthritis, 6 with juvenile chronic arthritis and 7 patients with spondarthritis) and followed prospectively. The average age at the operation was 40. 8 ± 10. 7 years. Each patient was clinically and radiologically examined preoperative, 3 and 6 months after the operation and at the end of each postoperative year. The mean follow-up was 26. 1 ± 10. 7 months. The clinical findings were evaluated using the Harris-Hip-Score. Radiologically 8 different zones at the thrust plate prosthesis were analyzed for radiolucencies.

Results

During the first year the Harris-Hip-Score rose continuously from the preoperative average of 42. 4 ± 6. 5 points to 78. 8 ± 10. 3 points 3 months postoperatively, 82. 3 ± 9. 8 points 6 months postoperatively, and 86. 8 ± 10. 1 points 1 year after the operation. The following examinations showed Harris-Hip-Scores at the same level. 5 patients (5 joints, 10. 6%) had to undergo a revision of the thrust plate prosthesis due to aseptic loosening in 3 cases and septic loosening in 2 cases. 6 prostheses (12. 6 %) showed radiolucencies, mostly below the thrust plate in zone 1 and 2. 2 of these prostheses were certainly radiologically loose which raised the failure rate to 7 of 47 (14. 8 %).

Conclusion

The thrust plate prosthesis improves function and pain in patients with polyarthritis to a satisfactory degree. Concerning the failure rate this type seems to yield slightly worse results than cementless stemmed endoprostheses in the same patient group. Due to the preservation of the diaphysial bone of the femur and the possibility of an unproblematic change to a stemmed endoprosthesis the thrust plate prosthesis keeps its indication in younger patients with polyarthritis.

Treatment with corticosteroids is a risk factor for non-traumatic avascular necrosis of the femoral head, but the pathological mechanism is poorly understood. Short-term treatment with high doses of methylprednisolone is used in severe neurotrauma and after kidney and heart transplantation. We investigated the effect of such treatment on the pattern of perfusion of the femoral head and of bone in general in the pig.

We allocated 15 immature pigs to treatment with high-dose methylprednisolone (20 mg/kg per day intramuscularly for three days, followed by 10 mg/kg intramuscularly for a further 11 days) and 15 to a control group. Perfusion of the systematically subdivided femoral head, proximal femur, acetabulum, humerus, and soft tissues was determined by the microsphere technique. Blood flow in bone was severely reduced in the steroid-treated group. The reduction of flow affected all the segments and the entire epiphysis of the femoral head. No changes in flow were found in non-osseous tissue. Short-term treatment with high-dose methylprednisolone causes reduction of osseous blood flow which may be the pathogenetic factor in the early stage of steroid-induced osteonecrosis.