Insufficient bone regenerate after intramedullary femoral lengthening: risk factors and classification system.

BACKGROUND: Control of distraction rate with an intramedullary skeletal kinetic distractor (ISKD) may be problematic and a high distraction rate may result in insufficient bone regenerate. QUESTIONS/PURPOSES: Are distraction problems preventable when using the ISKD, and what are the risk factors for and radiologic types of insufficient bone regenerate during ISKD lengthening? PATIENTS AND METHODS: We analyzed 37 consecutive ISKD femoral lengthening procedures in 35 patients with a mean age 33 ± 11 years and minimum followup of 12 months (average, 27 ± 9 months; range, 12-55 months). The average length gain was 42.8 ± 12.9 mm. RESULTS: Eight patients had problems during distraction: seven had "runaway nails" and one had a nondistracting nail. Insufficient bone regenerate developed in eight patients. Important risk factors were a distraction rate greater than 1.5 mm/day (9.1 times higher risk), age 30 years or older, smoking, and lengthening greater than 4 cm. Less important risk factors identified were creation of the osteotomy at the site of previous trauma or surgery and acute correction of associated deformities. We proposed a radiologic classification for failure of bone regeneration: partial regenerate failure (Type I) or complete failure resulting in a segmental defect subdivided according to a length of 3 cm or less (Type IIa) or greater than 3 cm (Type IIb). CONCLUSIONS: Distraction problems with the ISKD were related mostly to internal malfunction of the lengthening mechanism. A distraction rate greater than 1.5 mm/day should be avoided in femoral intramedullary lengthening. Smoking should be a contraindication for femoral lengthening. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Upright MRI measurement of mechanical axis and frontal plane alignment as a new technique: a comparative study with weight bearing full length radiographs.

OBJECTIVE: The purpose of this prospective study was to investigate the practicality, accuracy, and reliability of upright MR imaging as a new radiation-free technique for the measurement of mechanical axis. METHODS: We used upright MRI in 15 consecutive patients (30 limbs, 44.7 ± 20.6 years old) to measure mechanical axis deviation (MAD), hip-knee-ankle (HKA) angle, leg length, and all remaining angles of the frontal plane alignment according to Paley (mLPFA, mLDTA, mMPTA, mLDTA, JLCA). The measurements were compared to weight bearing full length radiographs, which are considered to be the standard of reference for planning corrective surgery. FDA-approved medical planning software (MediCAD) was used for the above measurements. Intra- and inter-observer reproducibility using mean absolute differences was also calculated for both methods. RESULTS: The correlation coefficient between angles determined with upright MRI and weight bearing full length radiographs was high for mLPFA, mLDTA, mMPTA, mLDTA, and the HKA angle (r > 0.70). Mean interobserver and intraobserver agreements for upright MRI were also very high (r > 0.89). The leg length and the MAD were significantly underestimated by MRI (-3.2 ± 2.2 cm, p < 0.001 and -6.2 ± 4.4 mm, p = 0.006, respectively). CONCLUSIONS: With the exception of underestimation of leg length and MAD, upright MR imaging measurements of the frontal plane angles are precise and produce reliable, reproducible results.

Effect of the lower limb rotational alignment on tibiofemoral contact pressure.

PURPOSE: The effect of the rotational alignment of lower extremities on the tibiofemoral contact mechanics is not known. This study was designed to measure the contact area and pressure within medial and lateral tibiofemoral compartments following controlled serial rotational deformities through femoral and tibial shafts. METHODS: Eight lower extremities of fresh frozen cadavers were used. Computed tomography was conducted to measure the rotational profile of the lower extremities. Through a medial parapatellar arthrotomy, pressure sensors were implanted into both tibiofemoral compartments. Femoral and tibial mid-shaft osteotomies were performed and stabilized by non-locked intramedullary nails and external fixators in neutral rotation. The contact area and pressure were measured under axial loading in neutral rotation and following serial malrotations from 40° external to 40° internal malrotation in 10° increments. RESULTS: Contact area was not affected by malrotations. Medial compartment contact pressure rose with external and decreased with internal malrotations whether femoral or tibial (P < 0.0001) while lateral pressure was not affected. When correlated with the cadavers' original rotational profile, decreased femoral neck anteversion was associated with increased medial pressure up to 28.5% at 20° of retroversion while it decreased with increased anteversion. On the other hand, decreased tibial torsion angle was associated with decreased medial pressure up to -32% at 10° of internal torsion and it increased with excessive external torsion. Furthermore, there was a strong positive correlation with the total rotational alignment as measured by the neck malleolar angle. CONCLUSION: A significant interaction could be detected between the rotational alignment of the lower extremity and medial tibiofemoral compartment contact pressures.

Comparison of 39 post-traumatic tibia bone transports performed with and without the use of an intramedullary rod: the long-term outcomes.

Bone transport can be performed with an external fixator alone or with the monorail technique which entails the combination of a fixator and an intramedullary nail. The purpose of this study was to compare the complication rates and long-term outcomes of these methods. Two groups of patients, the external fixator (n = 21) and the monorail group (n = 18), were compared. The average follow-up period was 7.9 ± 5.6 years and the mean defect length 8.3 ± 3.1 cm. Healing was achieved in 19 (90%) and 13 (72%) of the fixator and monorail patients, respectively. Six patients underwent amputations because of persistent infections (two in the fixator and four in the monorail group). The rate of deformities was significantly higher in the fixator group (p = 0.049). No statistically significant difference was found when comparing categories of the SF-36 test or the ability to work or do sports. The main advantages of the monorail method are reduction of the external fixation time and the lower rate of deformities. However, the authors recommend segmental transport with external fixator in patients with chronic infections.

Rotational alignment in total knee arthroplasty: intraoperative inter- and intraobserver reliability of Whiteside's line.

INTRODUCTION: Proper rotational alignment is a critical step of total knee arthroplasty. For intraoperative determination of femoral rotation, Whiteside suggests a perpendicular line to the axis of the center of the trochlea and the intercondylar notch (Whiteside's line). METHOD: In a prospective clinical study, the intraoperative position of Whiteside's line was measured in 30 patients with the help of a navigation system. RESULTS: Whiteside's line was 2.1° ± 1.5° externally rotated compared to a navigation based computer calculated preliminary AP axis of the femur. The intraobserver-reliability after 3 repeated measurements each was 1.6° for the senior surgeon and 1.4° for the junior surgeon (p = 0.598, p = 0.968). The interobserver reliability between the measurements by the senior and junior surgeon was 1.4° (p = 0.547). CONCLUSION: Navigated intraoperative measurements of Whiteside's line showed a high inter- and intraobserver reliability. Considering the variability between Whiteside's line and the transepicondylar axis, intraoperative assessment of both the methods is recommended.

Segmental transports for posttraumatic lower extremity bone defects: are femoral bone transports safer than tibial?

BACKGROUND: The long-term outcomes following femoral and tibial segment transports are not well documented. Purpose of the study is to compare the complication rates and life quality scores of femoral and tibial transports in order to find what are the complication rates of femoral and tibial monorail bone transports and if they are different? METHODS: We retrospectively analyzed the medical records of 8 femoral and 14 tibial consecutive segment transports performed with the monorail technique between 2001 and 2008 in our institution. Mean follow-up was 5.1 ± 2.1 years with a minimum follow-up of 2 years. Aetiology of the defects was posttraumatic in all cases. Four femoral (50%) and nine tibial (64%) fractures were open. The Short Form-36 (SF-36) health survey was used to compare the life quality after femoral and tibial bone transports. The Mann-Whiney U test, Fisher exact test, and the Student's two tailed t-test were used for statistical analysis. P ≤ 0.05 was considered to be statistically significant. RESULTS: The tibial transport was associated with higher rates of severe complications and additional procedures (1.5 ± 0.9 vs. 3.4 ± 2.7, p = 0.048). Three patients of the tibial group were amputated because of recurrent infections and one developed a complete regenerate insufficiency that was treated with partial diaphyseal tibial replacement. Contrary to that none of patients of the femoral group developed a complete regenerate insufficiency or was amputated. CONCLUSIONS: Tibial bone transports have a higher rate of complete and incomplete regenerate insufficiency and can more often end in an amputation. The authors suggest systematic weekly controls of the CRP value and of the callus formation in patients with posttraumatic tibia bone transports. Further comparative studies comparing the results of bone transports with and without intramedullary implants are necessary.

A new technique for removal of an incarcerated expandable femoral nail.

UNLABELLED: Removal of intramedullary nails often is relegated to younger surgeons but may be difficult and challenging. We describe difficulties with removal of an incarcerated expandable femoral nail and a new technique for retrograde mobilization of an intramedullary nail through a small infrapatellar incision. No special device was necessary for successful implant removal. LEVEL OF EVIDENCE: Level V, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Compartment syndrome of the lower leg and foot.

UNLABELLED: Compartment syndrome of the lower leg or foot, a severe complication with a low incidence, is mostly caused by high-energy deceleration trauma. The diagnosis is based on clinical examination and intracompartmental pressure measurement. The most sensitive clinical symptom of compartment syndrome is severe pain. Clinical findings must be documented carefully. A fasciotomy should be performed when the difference between compartment pressure and diastolic blood pressure is less than 30 mm Hg or when clinical symptoms are obvious. Once the diagnosis is made, immediate fasciotomy of all compartments is required. Fasciotomy of the lower leg can be performed either by one lateral incision or by medial and lateral incisions. The compartment syndrome of the foot requires thorough examination of all compartments with special focus on the calcaneal compartment. Depending on the injury, clinical examination, and compartment pressure, fasciotomy is recommended via a dorsal and/or medial plantar approach. Surgical management does not eliminate the risk of developing nerve and muscle dysfunction. When left untreated, poor outcomes with contractures, toe deformities, paralysis, and sensory neuropathy can be expected. In severe cases, amputation may be necessary. LEVEL OF EVIDENCE: Level III. See Guidelines for Authors for a complete description of levels of evidence.

The relation between tunnel widening and bone mineral density after anterior cruciate ligament reconstruction: an experimental study in sheep.

PURPOSE: The aim of this study was to analyze the relation between bone mineral density (BMD) and femoral tunnel enlargement (TE) in a previously validated sheep model of soft-tissue anterior cruciate ligament (ACL) reconstruction. METHODS: Thirty sheep underwent ACL reconstruction by use of a soft-tissue graft at the age of 4 months. Graft fixation was achieved with the EndoButton (Smith & Nephew Endoscopy, Andover, MA) and Suture Washer (Smith & Nephew Endoscopy). Six animals were killed at 0, 3, 6, 12, and 24 weeks postoperatively. Each ACL-reconstructed knee was examined both by computed tomography to analyze the bone tunnel cross-sectional area and by dual-energy x-ray absorptiometry to analyze BMD. RESULTS: There was a significant increase in tunnel cross-sectional area. BMD decreased significantly within the first 3 weeks after surgery and increased thereafter. A positive correlation between TE and BMD was found. However, a subgroup analysis showed that there is no influence of BMD on the development of a tunnel widening. CONCLUSIONS: The hypothesis that a TE would be associated with a loss in BMD was not confirmed. Tunnel widening during the first 6 months after ACL reconstruction is not affected by the transient changes in BMD. CLINICAL RELEVANCE: There is no correlation between TE and BMD in an experimental sheep model of ACL reconstruction. Translational investigations will determine whether this is also true in humans.

Influence of fibrin glue on proliferation and differentiation of human bone marrow stromal cells seeded on a biologic 3-dimensional matrix.

For tissue engineering of bone, a carrier matrix and efficient cell seeding are desirable. This study analysed the effect of fibrin glue on bone marrow stromal cells (BMSC) adhesion, proliferation (MTS-Test), differentiation (alkaline phosphatase (AP), osteocalcin (OC), ELISA) and compared the results with cells seeded within culture media on a decellularized, xenogenic bone matrix. There was no significant difference regarding cell adhesion. Proliferation after one week was significantly increased without fibrin glue. AP was increased in both groups when compared with porous scaffolds without cells. OC secretion was increased under both seeding conditions. Microscopic investigation of the cells with fibrin-glue showed less cell-cell contacts. This study reveals that cell seeding with medium demonstrates similar adherence rates compared with fibrin glue. Fibrin glue significantly decreases cell proliferation. Cell differentiation with respect to ALP and OC is not affected. Further studies are required to assess the long term and in vivo effects of both methods with respect to BMSC viability and differentiation. Fibrin sealants seem not necessary to achieve cell adherence when using a porous bone matrix.

Differences in the mechanical properties of calcaneal artificial specimens, fresh frozen specimens, and embalmed specimens in experimental testing.

BACKGROUND: Artificial calcanei, fresh-frozen cadaver specimens, and embalmed cadaver specimens were compared in experimental testing under biocompatible loading to clarify the biocompatibility of artificial calcaneal specimens for implant testing. METHODS: Two different artificial calcaneal bone models (Sawbone, Pacific Research Laboratories, Vashon, WA, and Synbone, Synbone Inc., Davos, Switzerland), embalmed cadaver calcaneal specimens (bone density, 313.1 +/- 40.9 g/cm2; age, 43.8 +/- 7.9 years), and fresh-frozen cadaver calcanei (bone density, 238.5 +/- 30.0 g/cm2; age, 44.4 +/- 8.2 years) were used for testing. Seven specimens of each model or cadaver type were tested. A mechanical testing machine (Zwick Inc., Ulm, Germany) was used for loading and measurements. Cyclic loading (preload 20 N, load was increased every 100 cycles by 100 N from 1,000 to 2,500 N, 0.5 mm/s) and load to failure (0.5 mm/s) were performed. The loads were applied through an artificial talus in a physiological loading direction. The displacement of the posterior facet in the primary loading direction was measured. RESULTS: The four different specimen groups showed different stability and different displacement in the primary loading direction during cyclic loading. The variation of the maximal displacement in the primary loading direction for the entire cyclic loading was higher in artificial specimens than in the cadaver specimens. CONCLUSIONS: Artificial calcanei (Sawbone, Synbone) showed different biomechanical characteristics than cadaver bones (embalmed and fresh-frozen) in this experimental setup with biocompatible cyclic loading. These results do not support the use of artificial calcanei for biomechanical implant testing. Fresh-frozen and embalmed specimens seem to be equally adequate for mechanical testing. The low variation of mechanical strength in the unpaired cadaver specimens suggests that the use of PAIRED specimens is not necessary.

[Arthroscopic partial meniscectomy].

OBJECTIVE: Excision of damaged meniscal tissue whereby the mechanical obstacles to joint movement are eliminated. As much functional, intact meniscal tissue should be retained as possible. Resection of only the bare minimum. INDICATIONS: Symptomatic, irreparable lesions of the meniscus due to trauma or degeneration. CONTRAINDICATIONS: Reparable lesions of the meniscus. Local skin affections. SURGICAL TECHNIQUE: Introduction of the arthroscope through an anterolateral or central portal. The instrument portal is positioned in accordance with the situation of the meniscal lesion to be treated. The tissue to be excised is either broken into fragments with different punches or resected en bloc. POSTOPERATIVE MANAGEMENT: Functional postoperative management without immobilization. Full loading on the leg. RESULTS: Very good and good clinical results can be achieved in the short and long term after arthroscopic partial meniscectomy. In a study by Burks et al., 88% of 146 patients with stable knee joints had a very good or good result 14.7 years after partial meniscectomy. 95% of 57 patients were satisfied or very satisfied with the result 12 years after partial medial meniscectomy. A degenerative meniscal tear, axial deformity, higher age, and anterior cruciate ligament insufficiency are factors associated with an increased rate of arthrosis in the long term.

Connection of a hip prosthesis and an intramedullary nail as a special solution in a subtrochanteric femoral fracture with fibrous dysplasia.

Treatment of fractures associated with fibrous dysplasia is difficult because of poor bone quality. In a brief report we present a case in which a hip prosthesis is connected with the distal part of a broken cannulated intramedullary femur nail. Postoperatively, the patient was mobilized with full weight bearing. Radiographs proved the correct position of the implant and a favorable clinical function could be achieved.

Modulation of proliferation and differentiation of human bone marrow stromal cells by fibroblast growth factor 2: potential implications for tissue engineering of tendons and ligaments.

Bone marrow stromal cells (BMSCs) play a central role in the repair and regeneration of mesenchymal tissues. For tissue engineering of ligaments and tendons, both stimulation of cell proliferation and differentiation with increased expression of essential extracellular matrix proteins and cytoskeletal elements are desirable. This study analyzes the effect of low-dose (3 ng/mL) fibroblast growth factor 2 (FGF-2) and high-dose FGF-2 (30 ng/mL) on proliferation (bromodeoxyuridine content, spectrophotometry), differentiation (transcription of collagen I, collagen III, fibronectin, elastin, alpha-smooth muscle actin, and vimentin, reverse transcription-polymerase chain reaction, and cell density and apoptosis (annexin V, fluorescence-activated cell sorting) of human BMSCs, and compares the results with those of a control group without FGF-2. Low-dose FGF-2 triggered a biphasic BMSC response: on day 7, cell proliferation reached its maximum and was significantly higher compared with the other groups. On days 14 or 28, collagen I, collagen III, fibronectin, and alpha- smooth muscle actin mRNA expression was significantly enhanced in the presence of low-dose FGF-2. In contrast, high-dose FGF-2 did not stimulate differentiation or proliferation. Vimentin mRNA was expressed only in cultures with low-dose and high-dose FGF-2 after 14 and 28 days. Cell density was significantly higher in cultures with low-dose FGF-2 compared with the group with high-dose FGF-2 on days 7, 14, and 28. The apoptosis rate remained stable, at a rather high level, in all groups. Microscopic investigation of the cell cultures with low-dose FGF-2 showed more homogeneous, dense, fibroblast-like, spindle-shaped cells with long cell processes compared with cultures with high-dose, or no FGF-2. Low-dose FGF-2 may be useful for tissue engineering of ligaments and tendons by increasing BMSC proliferation and stimulating mRNA expression of specific extracellular matrix proteins and cytoskeletal elements.

Minimally invasive exchange tibial nailing for a broken solid nail: case report and description of a new technique.

We present a minimally invasive technique for the removal of a broken solid tibial nail. A special device was invented that minimizes the extraction difficulties. After minimal over-reaming, the device is slid in an antegrade fashion over the nail and locked. Retraction is safe and easy. This article is an illustrative case-presentation describing the device and the surgical technique.

Limb lengthening with the Intramedullary Skeletal Kinetic Distractor (ISKD).

OBJECTIVE: Callus distraction of the femur or tibia with an intramedullary distractor, which lengthens mechanically through alternating rotations of at least 3 degrees. INDICATIONS: Femoral or tibial shortening between 20 and 80 mm. Angular and rotational deformities can be corrected at the osteotomy site. CONTRAINDICATIONS: Open epiphyses. Small medullary canal (after intramedullary reaming femoral diameter < 14.5 mm, tibial diameter < 12.5 mm). Severe deformities. Insufficient compliance. Osteitis. Soft-tissue infections. SURGICAL TECHNIQUE: Supine position. Femoral shaft osteotomy at the proximal or middle third by multiple drill holes completed with a chisel. For lengthening of the tibia, osteotomy with a Gigli saw is preferred. Control of the rotation by two parallel 3.0-mm Kirschner wires. Correction of angular or rotational deformities. Via stab incision reaming of the medullary canal with a flexible reamer. The femur is overreamed 2.0 mm and the tibia 1.5 mm above the desired implant diameter. Insertion of the Intramedullary Skeletal Kinetic Distractor (ISKD) into the medullary canal and distal locking in freehand technique. Control of the rotation and of the osteotomy gap. Proximal locking with an aiming device. For femoral lengthening 3 days and for tibial lengthening 5 days postoperatively the distraction is begun by increasing mobilization with partial weight bearing, to achieve daily distraction of 1 mm. In case of insufficient distraction, additional rotations are performed by the patient while checking the external monitor that displays the daily and total distraction length. RESULTS: Intramedullary lengthening with the ISKD was performed in four patients having an average age of 29 years (18-36 years). Two femoral shortenings were combined with complex rotational and angular deformities. The average lengthening of three femora and one tibia was 31 mm (26-40 mm). The average intraoperative blood loss was 230 ml (110-320 ml), the mean surgical time 108 min (90-145 min). The average daily distraction amounted to 1.2 mm (0.9-1.8 mm). Full weight bearing was permitted after 10 weeks (7-14 weeks), return to regular work after 11 weeks (7-16 weeks). At follow-up examination of an average of 2.3 years postoperatively the knee range of motion was full. Consolidation was noted 80 days (51-111 days) postoperatively with an average consolidation index of 2.9 days/mm (1.8-4.1 days/mm). No complications were observed. According to the Paley Score all patients had an excellent outcome.

The greater trochanter-head contact method: a cadaveric study with a new technique for the intraoperative control of rotation of femoral fractures.

OBJECTIVE: To describe a new method for femoral rotational alignment during intramedullary nail insertion using the profile of the greater trochanter and its relation to the femoral head. METHODS: Radiologically, the line that represents the posterior border of the greater trochanter comes in contact with the femoral head contour during external rotation. The degree of rotation to achieve this contact was measured on both lower extremities of 15 whole fresh-frozen cadavers and seven dried human femora using a standard image intensifier. Computed tomography was used in the dried femora to assess the femoral anteversion angle, the length of the femoral neck, and the neck-shaft angle. RESULTS: The side difference of the greater trochanter-head contact angle was 6° or less in 14 of 15 whole fresh-frozen cadavers. Regarding the dried human femora, this angle had a strong positive correlation with femoral neck anteversion angle (r = 0.9), whereas no statistically significant correlation could be detected with the neck length or the neck-shaft angle. CONCLUSION: Our described method is simple to execute because it depends on a definite point of measurement. Furthermore, an angle is recorded for each extremity, which enables us to estimate the amount of the rotational difference. This method does not depend on special views, especially at the hip, but only a direct anteroposterior view with gradual internal rotation of the image intensifier.

Leg lengthening using intramedullay skeletal kinetic distractor: results of 57 consecutive applications.

BACKGROUND: Mechanically activated intramedullary lengthening nails are advantageous over external fixator. However, difficulties with the control of the distraction rate are the main drawbacks, which may in turn cause insufficient bone regenerate. PATIENTS AND METHODS: A total of 57 lengthening procedures were performed using intramedullary skeletal kinetic distractor (ISKD) nail in 53 patients (femoral = 45 and tibial = 12). Average length gain was 4.3 ± 1.6 cm. The cause of shortening was post-traumatic (n = 33), congenital (n = 20), post-tumour resection (n = 1), cosmetic femoral lengthening (n = 2) and post-correction of distal femoral varus deformity (n = 1). RESULTS: The desired lengthening was achieved in all patients. The mean follow-up period was 23 ± 12 months. The healing index for patients with normal bone healing was 1.2 ± 0.32 months/cm. Complications in femoral lengthening were superficial wound infection (n = 1), premature consolidation (n = 4) and insufficient bone regenerate (n = 11), while in the tibial lengthening, two developed equinus contractures,one had compartment syndrome following implantation of the nail and one insufficient bone regenerate.Furthermore, nine runaway nails and three non-distracting nails were present in the femoral lengthening.One non-distracting nail responded to manipulation under anaesthesia, one required exchange nailing and accidental acute lengthening of 3 cm took place while manipulating the third nail. Patients with femoral lengthening and those with insufficient regenerate had significantly higher distraction rates (P = 0.006 and 0.003, respectively). Six out of the nine runaway nails developed insufficient bone regenerate. In addition,10.7-mm tibial ISKD nails were found to have lower rates of runaway nails compared with other used diameters. CONCLUSION: We emphasise the rule of distraction rates above 1.5 mm/day in the development of insufficient bone regenerate. Distraction problems with these nails are mostly due to dysfunction within the ratcheting mechanism, which may be related to the diameter of the nail. New designs for mechanically activated nails with a better control mechanism for the distraction rate are required.

Biodegradable screw versus a press-fit bone plug fixation for hamstring anterior cruciate ligament reconstruction: a prospective randomized study.

BACKGROUND: Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing. HYPOTHESIS: Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. Methods Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years. RESULTS: The bone tunnel enlargement determined by CT was 106.9% + or - 10.9% for group P and 121.9% + or - 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% + or - 15.2% versus 121.5% + or - 10.1% in the coronal plane (P <.01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 + or - 1.4 mm vs 1.8 + or - 1.5 mm; P = .08). CONCLUSION: Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.

Bone marrow stromal cells in a liquid fibrin matrix improve the healing process of patellar tendon window defects.

Following injury, ligaments and tendons do not regain their normal biological and biomechanical status. This study analyzed whether an injection of human bone marrow stromal cells (BMSC) or human fibroblast in a liquid fibrin matrix influences the histological results, ultrastructural morphology, mRNA expression of essential extracellular matrix proteins, and material properties of the healing tissue. Standardized full-thickness, full-length defects of the central portion of patellar tendons were created in 96 immunodeficient rats, and filled with human BMSC in a fibrin matrix (BMSC group), human fibroblasts in a fibrin matrix (fibroblast group), or fibrin matrix only (matrix group), or left untreated (defect group). Histological sections revealed more mature tissue formation with more regular patterns of cell distribution in the BMSC group, without signs of ectopic tissue formation into bone or cartilage. Mean collagen fibril diameter and relative area covered by collagen fibrils were significantly higher at 10 and 20 days postoperatively in the BMSC group compared to the defect and matrix groups, and comparable to normal tendon tissue. Further, collagen I mRNA expression, collagen I/collagen III mRNA ratio, and Young's modulus were significantly increased at 20 days postoperatively in comparison to the defect and matrix groups. In the fibroblast group, only mean collagen fibril diameter was significantly higher compared to the defect group, whereas the other biological and biomechanical parameters were not significantly improved. This study reveals that an injection of BMSC in a liquid fibrin matrix stimulates histological, ultrastructural, molecular biologic, and biomechanical parameters of patellar tendon healing, whereas injection of fibroblasts in fibrin matrix had only minor effects on the stimulation of tendon healing.