Ulrich Bosch

Comparison of human bone marrow stromal cells seeded on calcium-deficient hydroxyapatite, beta-tricalcium phosphate and demineralized bone matrix.

The aim of this study was to compare three resorbable biomaterials regarding seeding efficacy with human bone marrow stromal cells (BMSCs), cell penetration into the matrix, cell proliferation and osteogenic differentiation. Calcium-deficient hydroxyapatite (CDHA), beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSCs and kept in human serum and osteogenic supplements for 3 weeks. Morphologic and biochemical evaluations were performed on day 1, 7, 14 and 21. The allograft DBM and CDHA exhibited both an excellent seeding efficacy while the performance of beta-TCP was lower when compared. The total protein content and the values for specific alkaline phosphatase (ALP) increased on all matrices and no significant difference was found for these two markers. BMSCs in monolayer had a significant increase of protein, but not of ALP. Osteocalcin (OC) values increased significantly higher for BMSC in cultures on DBM when compared to CDHA and beta-TCP. The OC levels decreased significantly in the BMSC monolayer culture. BMSCs were found inconsistently within the synthetic materials, whereas in DBM they were found more homogeneously distributed throughout the matrix. All three matrices promoted BMSC proliferation and differentiation to osteogenic cells. DBM allografts seem to be more favorable with respect to cell ingrowth tested by histology, and osteogenic differentiation ascertained by an increase of OC. CDHA with its high specific surface area showed more favorable properties than beta-TCP regarding reproducibility of the seeding efficacy.

Outcome after primary and secondary hemiarthroplasty in elderly patients with fractures of the proximal humerus

Thirty-nine consecutive patients with 3- and 4-part proximal humeral fractures and fracture dislocations were treated with hemiarthroplasty. After an average of 42 months (range 5 to 98 months) of follow-up, 17 women and 8 men (average age 64.5 years) were evaluated with the University of California-Los Angeles (UCLA) scale, the Constant-Murley scale, the Hospital for Special Surgery (HSS) scale, and the visual analogue scale. Fair, good, or excellent results were achieved in 80% of the patients on the UCLA and Visual scales, in 72% of the patients on the HSS scale, and in 44% of the patients on the Constant-Murley scale. The highest correlation was between the HSS score and the Visual analogue score. According to the UCLA and Constant-Murley results, the outcome after early (<4 weeks) humeral head replacement was significantly better than after late (> or =4 weeks) humeral head replacement (UCLA score, P=.02; Constant-Murley score, P=.01). After early hemiarthroplasty active forward flexion was significantly better (P=.035). Thus the decision to perform prosthetic humeral head replacement in elderly patients should be made as early as possible after trauma.

Comparison of Surgical Repair or Reconstruction of the Cruciate Ligaments versus Nonsurgical Treatment in Patients with Traumatic Knee Dislocations

Background: Studies of traumatic knee dislocations have failed to provide a consensus regarding the best method of treatment. Purpose: Our purpose was to evaluate the results after surgical repair or reconstruction versus nonsurgical treatment and to compare the influence of prognostic factors. Study Design: Retrospective study. Methods: Eighty-nine patients were treated for traumatic knee dislocation. Surgical repair or reconstruction of the cruciate ligaments was performed in 63 patients (repair, 49; reconstruction, 14). In 26 patients, nonsurgical treatment was undertaken. Results: At an average follow-up of 8.2 years, the mean Lysholm and Tegner scores were 75 and 3.7, respectively. The outcome in the surgical group was better than in the nonsurgical group. The scores were higher in patients who were 40 years of age or younger, who had sports injuries rather than motor vehicle accident injuries, and who had undergone functional rehabilitation rather than immobilization. Conclusions: Surgical repair or reconstruction of the cruciate ligaments was superior to nonsurgical treatment. Functional rehabilitation was the most important positive prognostic factor. Surgical repair or reconstruction of the cruciate ligaments is mandatory to achieve sufficient stability for functional rehabilitation. In cases of cruciate ligament avulsion, repair with transosseous fixation is a reasonable alternative to reconstruction, provided that it is performed within 2 weeks of trauma.

The Proliferative Response of Isolated Human Tendon Fibroblasts to Cyclic Biaxial Mechanical Strain

At the cellular level, dynamic strain plays a key role in cell stimulation and organization of the extracellular matrix. Although positive effects of physical strain on tendon tissue are well known, little knowledge exists on how mechanical strain affects tendon cells. In this study, human tendon fibroblasts from patellar tendon were cultured on silicone dishes. Subsequently, cyclic biaxial mechanical strain was applied to the dishes for 15, 30, and 60 minutes using a specially developed cell stretching system. After the fibroblasts were strained, cells were tested for proliferation at 6, 12, and 24 hours. As a control, cells were grown on silicone dishes but did not receive any strain. A biphasic response in proliferation was observed for the 15- and 60-minute strain periods: at 6 hours and 24 hours there was more proliferation than at 12 hours. After a strain duration time of 30 minutes, a lower proliferation rate was measured compared with control levels. This study shows that application of mechanical stress to tendon fibroblasts resulted in an alteration of cellular proliferation depending on the stress time. Our results may implicate future modifications in the treatment of ligament and tendon injuries.

Proprioception after rehabilitation and reconstruction in knees with deficiency of the anterior cruciate ligament : a prospective, longitudinal study

We assessed proprioception in the knee using the angle reproduction test in 20 healthy volunteers, ten patients with acute anterior instability and 20 patients with chronic anterior instability after reconstruction of the anterior cruciate ligament (ACL). In addition, the Lysholm-knee score, ligament laxity and patient satisfaction were determined. Acute trauma causes extensive damage to proprioception which is not restored by rehabilitation alone. Three months after operation, there remained a slight decrease in proprioception compared with the preoperative recordings, but six months after reconstruction, restoration of proprioception was seen near full extension and full flexion. In the mid-range position, proprioception was not restored. At follow-up, 3.7 +/- 0.3 years after reconstruction, there was further improvement of proprioception in the mid-range position. There was no difference between open and arthroscopic techniques. The highest correlation was found between proprioception and patient satisfaction. After reconstruction of the ACL reduced proprioception may explain the poor functional outcome in some patients, despite restoration of mechanical stability.

Shearing and Bending Effects at the Knee Joint at High Speed Lateral Loading

The main objective of this study is to determine the damage tolerance and describe the damage mechanisms of the extended human knee when it is exposed to lateral impact loads in car-pedestrian accidents, particularly those that occur at a low velocity (20 kph), and compare the results with those obtained at a high velocity (40 kph). In-Vitro experiments with human subjects were conducted where only the purest possible shearing deformation or the purest possible bending deformation affected the knee region. When the knee joint was exposed to deformation, the common initial damage mechanism was ligament damage related to ACL (60%). This type of damage occurred when mean values of the peak shearing force and the peak bending moment acting at the knee joint level were 2.4 kN and 418 Nm, and the shearing displacement and bending angle were 16 mm and -2.9 deg (-0.05 rad), respectively. When the knee joint was exposed to deformation, the most common initial damage mechanism (40%) was ligament damage related to MCL. The mean values of the peak shearing force and the peak bending moment calculated when this damage occurred were 1.6 kN and 358 Nm, respectively. This type of initial damage occurred when the knee was bent 12.3 deg (0.22 rad). The initial metaphysics fracture of the femur due to bending deformation of the knee was observed in only 20% of the cases. The mean values of the peak shearing force and the peak bending moment developed at knee joint level that correspond to this damage were 0.9 kN and 205 Nm. This type of damage occurred when the knee was bent 12.3 deg (0.22 rad). The physical values of the shearing force and the bending moment at the time of initial damage for low-speed lateral loading were found to be similar with those from previously performed experiments at high-speed lateral loading. The ratio of bone fracture to ligament damage was 0.3 in the shearing deformation test and 0.5 in the bending deformation test at low speed.

Healing of the patellar tendon autograft after posterior cruciate ligament reconstruction— a process of ligamentization? An experimental study in a sheep model

Forty-eight skeletally mature sheep underwent poste rior cruciate ligament reconstruction with free patellar tendon autografts in one knee; the contralateral knee served as a control. Immediate rehabilitation without immobilization followed. Autograft healing was evalu ated by histologic, roentgenographic, and biomechani cal techniques up to 2 years postoperatively. After implantation, the autograft tissue underwent necrosis and degeneration, followed by a gradual healing proc ess comprising revascularization, cellular migration, and formation of an extracellular matrix. The autograft bone pegs were osseously incorporated by 6 weeks. After an initial loss of strength, the material properties of the operated knee recovered to only about one-third that of the control. Better alignment of the collagen fiber bundles resulted in increased material properties, up to approximately 50% of the control at 52 weeks. After 2 years, the autograft tissue was found to differ structur ally and mechanically from a ligament, suggesting that the autograft may never approach normal ligament characteristics. Degenerative alterations, the wide spread presence of type III collagen, and abnormal accumulations of glycosaminoglycans in the autograft correlated with a maximum stress of 60% and an elastic modulus of 70% of the control. Although ligamentiza tion was not seen, the staging of autograft healing into different phases based on distinct morphologic mani festations (necrosis, revitalization, collagen formation, and remodeling) and correlating with changing mechan ical properties may provide a rationale for rehabilitation protocols with a realistic evaluation of the loading ca pacity of the replacement tissue.

Reduction and fixation of displaced intracapsular fractures of the proximal femur.

Intracapsular fractures of the femoral neck are one of the most common fractures in the elderly. The incidence of these fractures will increase significantly in the next decades as a result of increasing life expectancy. Although treatment of these fractures by closed or open reduction and internal fixation is standard in young patients, arthroplasty is the standard treatment in geriatric patients in most countries. Comorbidities of the patients and current socioeconomic changes in healthcare led to reconsideration of closed reduction and internal fixation of femoral neck fractures as an alternative treatment modality. With correct decision-making, proper reduction, and proper consideration of the biomechanical principle of three-point fixation, minimally invasive screw fixation of femoral neck fractures is a safe and inexpensive procedure even in elderly patients. The purpose of the current review was to give an overview of the history, current techniques and developments, results, limitations, and complications of closed reduction and internal fixation of intracapsular femoral neck fractures.

Outcome analysis following open rotator cuff repair. Early effectiveness validated using four different shoulder assessment scales.

Abstract Evaluation of upper extremity function after reconstructive surgery is increasingly important both to predict outcome and for the control of cost-effectiveness. Three validated, self-administered shoulder questionnaires were applied prospectively in 23 otherwise healthy patients with rotator cuff deficiency and correlated to the Constant-Murley Shoulder Score and a visual analogue scale for satisfaction. Seven women and 16 men with combined tears of supraspinatus and infraspinatus (mean age 55.3 ± 10.5 years, r/l: 14/9, follow-up 57.8 ± 15.7 weeks) were gathered prospectively and evaluated pre- and postoperatively with the American Shoulder and Elbow Surgeons (ASES) Shoulder Index, the Simple Shoulder Test (SST) and the Disabilities of the Arm, Shoulder and Hand Module (DASH questionnaire). Additionally, a visual analogue scale for satisfaction was employed. All four scores and the visual analogue scale revealed improvement at a statistically significant level (P < 0.01) after surgery. All questionnaires showed a significant correlation with the Constant-Murley Shoulder Score (ASES: r = 0.871, P < 0.01; DASH: r = –0.758, P < 0.01, SST: r = 0.494, P < 0.05, Pearson’s correlation coefficient). Taken together, all questionnaires were easy to apply, and reliable evaluation of shoulder function was possible with significant correlation to the Constant-Murley Shoulder Score postoperatively. The SST was easy to apply, and compound outcome analysis was possible with the ASES Shoulder Index and DASH questionnaire. The DASH scale was the most complex evaluation instrument. The Constant-Murley Shoulder Score comprises a physical examination, which is advantageous but restricts the application to the office. For postoperative assessment without the patient having to return to the clinic, the ASES Shoulder Index is preferred because of its good correlation to the Constant-Murley Shoulder Score (r = 0.871) and the visual analogue scale for satisfaction (r = 0.762).

Modulation of cell functions of human tendon fibroblasts by different repetitive cyclic mechanical stress patterns.

Mechanical stress is a factor that is thought to play an essential role in tissue generation and reparation processes. The aim of the present study was to investigate the influence of different repetitive cyclic longitudinal stress patterns on proliferation, apoptosis and expression of heat shock protein (HSP) 72. To perform this study, human tendon fibroblasts were seeded on flexible silicone dishes. After adherence to the dish, cells were longitudinally stressed with three different repetitive stress patterns having a frequency of 1 Hz and an amplitude of 5%. The proliferation and apoptosis rates were investigated 0, 6, 12 and 24 hours after application of cyclic mechanical longitudinal strain. Expression of HSP 72 was tested after 0, 2, 4 and 8 hours. Control cells were also grown on silicone dishes, but did not receive any stress. Stress patterns applied during one day resulted in a significant increase in proliferation and a slight increase in apoptosis. HSP 72 expression was rather unchanged. A stress pattern applied during two days resulted in a reduced proliferation and apoptosis rate whereas the expression of HSP 72 showed a significant increase. This study shows that different stress patterns result in different cellular reactions dependent on the strength of applied stress. Repetitive stress applied during one day stimulated proliferation and apoptosis in contrast to an extended stress duration. The latter induced an inhibition of proliferation and apoptosis probably through an increased HSP 72 activity. This may be related to an excess of applied stress. Our results may implicate future modulation techniques for tissue reparation and tissue engineering.