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Biomedical subjects

Oliver Rühmann

Publications and source records attributed to Oliver Rühmann.

17 recordsLinked to original sources
PubMed2006

Influence of an infrapatellar fat pad edema on patellofemoral biomechanics and knee kinematics: a possible relation to the anterior knee pain syndrome.

INTRODUCTION: An edema of the infrapatellar fat pad following knee arthroscopy or in case of chronic anterior knee pain syndrome is suspected to increase the patellofemoral pressure by a modification of the patellofemoral glide mechanism. The study was performed to evaluate this hypothesis. MATERIALS AND METHODS: Isokinetic knee extension from 120 degrees of flexion to full extension was simulated on 10 human knee cadaver specimens (six males, four females, average age at death 42 years) using a knee kinemator. Joint kinematics was evaluated by ultrasound sensors (CMS 100, Zebris, Isny, Germany), and retro-patellar contact pressure was measured using a thin-film resistive ink pressure system (K-Scan 4000, Tekscan, Boston). Infrapatellar tissue pressure was analyzed using a closed sensor cell which was implanted inside the fat pad (GISMA, Buggingen, Germany). An inflatable fluid cell was implanted by ultrasound control in the center of the infrapatellar fat pad and filled subsequently with water to simulate a fat pad edema. All parameters were recorded and analyzed from 0 to 5 ml volume of the fluid cell. RESULTS: Simulating a fat pad edema resulted in a significant (P < 0.01) increase of the infrapatellar fat pad pressure (247 mbar at 0 ml to 615 mbar at 5 ml volume). In knee extension and flexion the patella flexion (sagittal plane) was decreased while we did not find any other significant influence of the edema on knee kinematics. During the analysis of the patellofemoral biomechanics, a simulated fat pad edema resulted in a significant (P < 0.05) decrease of the patellofemoral force between 120 degrees of knee flexion and full extension. The contact area was reduced significantly near extension (0 degree-30 degrees) by an average of 10% while the contact pressure was reduced at the entire range of motion up to 20%. CONCLUSION: An edema of the infrapatellar fat pad does not cause an increase of the patellofemoral pressure or a significant alteration of the patellofemoral glide mechanism. Anterior knee pain in case of a fat pad edema may be related to a significant increase of the tissue pressure and possible histochemical reactions.

Adipose Tissue↗
PubMed2006

[Arthroscopic meniscal repair with bioresorbable implants].

OBJECTIVE: Restoration of the shape and function of a torn meniscus. INDICATIONS: Complete or large incomplete longitudinal tear of the medial and lateral meniscus close to the base, large flap tear, so-called bucket-handle tear. CONTRAINDICATIONS: Degenerative meniscal tissue. Unstable knee joint without concomitant surgical stabilization. Complex meniscal tear or radial tear. Tear in the central avascular region. Gonarthrosis. Joint infection. Local skin disorders. SURGICAL TECHNIQUE: Visualization of the meniscal tear and revitalization of the tear margins with a meniscal rasp or shaver. Introduction of the implant using the surgical technique required and repair of the tear. Percutaneous trepanation of the meniscal base ("needling") to improve healing. POSTOPERATIVE MANAGEMENT: Full weight bearing only with the knee joint extended in an orthosis until after the 6th postoperative week. Knee flexion up to 30 degrees without weight bearing for the first 2 postoperative weeks with physiotherapy, then up to 60 degrees for another 4 weeks. Short movable knee orthosis with 0-0-90 degrees in the 7th-12th postoperative week. After the 12th postoperative week, continuation of physiotherapy without orthosis, until range of movement has been achieved and the knee-stabilizing muscles have regained their strength. Full sporting capacity after 6 months. RESULTS: The healing rate for meniscal repair with bioresorbable implants is between 86% and 95% and is comparable with the average healing rate for open (84-88%) or arthroscopic suture techniques (98%). Between July 1999 and June 2001, a meniscal tear was treated with Clearfix screws in 65 patients. 60 patients (92%) had a follow-up examination on average 18 months postoperatively. Six patients underwent further arthroscopic surgery as a result of pain (four times healed, twice not healed). Another three patients complained of pain on weight bearing at the follow-up examination and had clinically positive meniscus signs. These patients were then evaluated as "treatment failures". The clinical healing rate was therefore 92% (55 out of 60).

Absorbable Implants↗
PubMed2005

Distribution of substance-P nerves inside the infrapatellar fat pad and the adjacent synovial tissue: a neurohistological approach to anterior knee pain syndrome.

INTRODUCTION: The purpose of the study was to determine the distribution and number of nerves inside the infrapatellar fat pad and the adjacent synovium, in particular with regards to nociceptive substance-P nerves. MATERIALS AND METHODS: The infrapatellar fat pad of the knee was resected from 21 patients (4 male, 17 female, mean age 69 years) during the course of standard total knee arthroplasty operations performed in our clinic. The fat pad was dissected into five standardized segments, fixed in formalin and embedded in paraffin. Immunohistochemical techniques using antibodies against S-100 protein and substance-P (SP) were employed to determine and specify the nerves. RESULTS: Studying all the detectable nerves present in 50 observation fields (200-fold magnification), we found an average of 106 S-100 versus 25 SP nerves (24%) in the synovium and 27 S-100- versus 7 SP nerves (26%) in the interior of the fat pad. The total nerve count was significantly (P < 0.001) higher in the synovium than in the fat pad for both marker types. The number of S-100 nerves was significantly (P < 0.05) higher in the central and lateral segments of the fat pad, while SP nerves were equally distributed throughout all segments of the fat-pad. SP nerves were significantly more frequently associated with blood vessels inside the fat pad (43%, P < 0.05) than in the synovial tissue (28%). CONCLUSION: The occurrence and distribution of SP nerves inside the infrapatellar fat pad suggest a nociceptive function and a neurohistological role in anterior knee pain syndrome. The data support the hypothesis that a neurogenous infection of the infrapatellar fat pad could contribute to anterior knee pain syndrome.

Aged↗
PubMed2004

Infrapatellar fat pad pressure and volume changes of the anterior compartment during knee motion: possible clinical consequences to the anterior knee pain syndrome.

This biomechanical study was performed to measure tissue pressure in the infrapatellar fat pad and the volume changes of the anterior knee compartment during knee flexion-extension motion. Knee motion from 120 degrees of flexion to full extension was simulated on ten fresh frozen human knee specimens (six from males, four from females, average age 44 years) using a hydraulic kinematic simulator (30, 40, and 50 Nm extension moment). Infrapatellar tissue pressure was measured using a closed cell sensor. Infrapatellar volume change in the anterior knee compartment was evaluated subsequent to removal of the fat pad using a water-filled bladder. We found a significant increase of the infrapatellar tissue pressure during knee flexion, at flexion angles of <20 degrees and >100 degrees . The average tissue pressure ranged from 343 (+/-223) mbar at 0 degrees to 60 (+/-64) mbar at 60 degrees of flexion. The smallest volume in the anterior knee compartment was measured at full extension and 120 degrees of flexion, whereas the maximum volume was observed at 50 degrees of flexion. In conclusion, the data suggest a biomechanical function of the infrapatellar fat pad at flexion angles of <20 degrees and >100 degrees , which suggests a role of the infrapatellar fat pad in stabilizing the patella in the extremes of knee motion.

Adipose Tissue↗
PubMed2004

Risk evaluation of thermal injury to the cervical spine during intradiscal laser application in vitro.

OBJECTIVE: We aimed to investigate temperature distribution during laser and its possible thermal damage to the neurovascular structures. BACKGROUND DATA: Percutaneous laser disc decompression (PLDD) is now being performed as a minimally invasive intradiscal technique for the operative therapy of non-sequestered herniated cervical discs. As yet, no experimental basic research has been reported with regard to temperature rise and distribution in the cervical region during laser radiation. MATERIALS AND METHODS: An in vitro laser procedure was performed on human cervical intervertebral discs under standardized conditions. A thermo-camera was used to monitor in real-time the zones sensitive to temperature increase. RESULTS: Average intervertebral disc volume was 2000 mm3. With a total energy conduction of 600 Joules, a temperature increase of around 30 degrees C was shown with an initial temperature of 28 degrees C at the posterior longitudinal ligament lying immediately in front of the myelon. The defect volume was less than 1% of the total intervertebral disc volume. CONCLUSION: If, during laser application, the total amount of conducted energy is too high, with an unfavorable position of the fibers in the intervertebral space, there is a risk of thermal damage to the spinal cord and nerve roots.

Cervical Vertebrae↗
PubMed2004

Biomechanical and kinematic influences of a total infrapatellar fat pad resection on the knee.

BACKGROUND: This biomechanical study was performed to evaluate the consequences of total infrapatellar fat pad resection on knee kinematics and patellar contact pressure. HYPOTHESIS: Resection of the infrapatellar fat pad produces significant changes in knee kinematics and patellar contact pressure. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Isokinetic knee extension was simulated on 10 human knee cadaveric specimens (6 men, 4 women; mean age at death, 44 years). Joint kinematics were evaluated by an ultrasound-based 3D motion analysis system, and retro-patellar contact pressure was measured using an electronic pressure-sensitive film. All data were taken before and after resection of the infrapatellar fat pad and statistically analyzed. RESULTS: A total resection of the infrapatellar fat pad resulted in a significant decrease of the tibial external rotation relative to the femur between 63 degrees of flexion and full knee extension (maximum: 3 degrees rotation difference at 0 degrees knee flexion, P = .011), combined with a significant medial translation of the patella between 29 degrees and 69 degrees of knee flexion (range, 0.9-1.3 mm, P = .017-.028). Retro-patellar contact pressure was significantly reduced (from 20% to 25%, P = .008-.021) at all flexion angles. CONCLUSION: A resection of the infrapatellar fat influences patellar biomechanics and knee kinematics. CLINICAL RELEVANCE: The infrapatellar fat pad may have a biomechanical function and may play a role in anterior knee pain syndrome.

Adipose Tissue↗
PubMed2004

Reconstructive operations for the upper limb after brachial plexus palsy.

Limited function due to paralysis following brachial plexus lesions can be improved by secondary operations of the bony and soft tissue. Between April 1994 and December 2000, 109 patients suffering from arm-plexus lesions underwent a total of 144 reconstructive operations guided by our concept of integrated therapy. The average age at the time of surgery was 32 years (range: 15-59). The following operations were performed: shoulder arthrodesis (23), trapezius transfer (74), rotation osteotomy of humerus (9), triceps to biceps transposition (9), transposition of forearm flexors or extensors (8), latissimus transfer (7), pectoralis transfer (1), teres major transfer (1), transposition of flexor carpi ulnaris to the tendons of extensor digitorum (10), and wrist arthrodesis (2). Prospectively, in all patients, the grade of muscle power of the affected upper extremity was evaluated prior to surgery. The follow-up period for all 144 operations was, on average, 22 months (range: 6-74). By means of operative measures, almost all patients obtained an improvement of shoulder function (100%) and stability (>90%), elbow flexion (85%), and hand, finger, and thumb (100%). When muscles malfunction after brachial plexus lesions, one should take into account the individual neuromuscular defect, passive joint function, and bony deformities; different procedures such as muscle transpositions, arthrodeses, and corrective osteotomies can then be performed to improve function of the upper extremity. Each form of operative treatment presents patients with certain benefits and all are integrated into a total treatment plan for the affected extremity.

Adolescent↗
PubMed2003

Clinical results of arthroscopic meniscal repair using biodegradable screws.

This study was performed to assess the clinical results of meniscus refixation using biodegradable Clearfix meniscal screws. Between July 1999 and June 2001 this technique was performed on 65 patients, of whom 60 (27 women, 33 men; 92%) were followed up by clinical examination after an average of 18 months (range 8-34). The average age of the patients at the time of surgery was 30 years (15-58). Two patients had already undergone a partial meniscectomy at the time of follow up; three patients had had a recurrence of typical clinical signs of a meniscal tear. The other 55 patients rated the overall clinical result as "excellent" (n=21), "good" (n=31) or "satisfactory" (n=3). The average Lysholm score [20] at the time of examination was 93 (49-100) points. The Tegner-Lysholm activity grade [29] preinjury was 5.6 (3-9), compared to a grade of 5.1 (3-9) at the follow-up examination. As a result of our study, biodegradable screws can be recommended as fixation devices with a high rate of good and excellent clinical results.

Absorbable Implants↗
PubMed2003

The influence of limited postoperative weight-bearing on the outcome of drilling in osteochondritis dissecans tali.

INTRODUCTION: This prospective study was performed to assess the influence of limited weight-bearing on the outcome of osteochondral drilling in the treatment of an osteochondritis dissecans tali. MATERIALS AND METHODS: Of a total of 85 patients, 68 (80%; 37 male, 31 female, average age 28 years) were followed up after open or arthroscopic drilling between July 1990 and March 2000. The total outcome of 6 weeks limited postoperative weight-bearing (n=26) was compared with the outcome of 12 weeks limited weight-bearing (n=42). The average follow-up time was 4.8 years after surgery. RESULTS: A significant increase (p<0.01) in the HSS and AOFAS scores was found for the entire study group ranging from HSS: 82 points; AOFAS: 68 points before surgery to HSS: 94 points; AOFAS: 90 points at the time of assessment. The duration of limited weight-bearing did not significantly influence the outcome of surgery. Through osteochondral drilling, the average AOFAS score increased 20 points (73/93) and the HSS score 12 points (84/96) in the 6-week group and the AOFAS score 23 points (65/88) and the HSS score 12 points (80/92) in the 12-week group. The total outcome between the two postoperative treatment regimens showed no significant difference. CONCLUSION: Osteochondral drilling is an adequate therapy for osteochondritis dissecans tali. The postoperative duration of limited weight-bearing does not significantly influence the surgical outcome.

Adolescent↗
PubMed2002

Long-term outcome following high tibial osteotomy with tension bend principle.

BACKGROUND: High tibial osteotomy has been successfully performed on patients with varus gonarthrosis for many years now. The prospective study presented here serves to verify the long-term outcome of this procedure. METHODS: A supratuberous high tibial osteotomy was carried out on 100 patients with varus gonarthrosis. Since then, 5 patients have died, and 6 patients could not be traced. The regaining rate was 94%. From a total of 89 patients with 101 operated knee joints, 46 were men and 43 women. The mean age at the time of surgery was 58 years. The patients were clinically and radiologically examined 10 years postoperatively and the knee score and function score ascertained according to the International Knee Society. RESULTS: The knee score showed a statistically significant increase from 31 points prior to surgery to 79 points at the time of follow-up; the function score likewise increased from 46 points to 78 points. In addition, 77.5% of patients would undergo the same surgery again, while 79% of patients claimed their condition to have improved following surgery. The preoperative full-length weight-bearing radiograph demonstrated an axis shift in the varus position of on average 9.6 degrees at 10 years postoperatively, an overcompensation in the valgus position of 1 degrees on average. At the time of follow-up, 81% did not require repeat surgery of the knee. CONCLUSION: With a correct diagnosis and accurate surgical techniques, positive clinical and radiological long-term results can be expected. Therefore, high tibial osteotomy may constitute an important contribution to our algorithm in the treatment of varus gonarthrosis.

Adult↗
PubMed2002

The value of knee arthroscopy in patients with severe radiological osteoarthritis.

BACKGROUND: This study was performed to assess the value of knee arthroscopy in patients with radiological signs of severe osteoarthritis. METHODS: A total of 104 patients (50 men, 54 women, average age 60 years) with radiological knee osteoarthritis grade III/IV were followed up after knee arthroscopy between May 1989 and November 1996. The average follow-up time was 5.4 years after surgery. RESULTS: A significant ( p<0.01) increase in the Lysholm score was found, ranging from 40 points before arthroscopy to 69 points at the assessment. A total of 84 patients (81%) reported an increase in their activities of daily living, 44 patients (43%) were still without any complaints. The total outcome was rated very good or good by 67 patients (65%). Only 21 patients (20%) required further surgery before the assessment. CONCLUSIONS: Knee arthroscopy is a valuable treatment for patients with pain, swelling, and radiological signs of severe osteoarthritis. It improves the patients' activities of daily living and helps to postpone further surgery.

Activities of Daily Living↗
PubMed2002

Transposition of local muscles to restore elbow flexion in brachial plexus palsy.

Between 1994 and 2001, triceps to biceps transfers were done in 10 men and a transfer of the forearm flexors and extensors (Steindler procedure) in nine. All had suffered from a post-traumatic lesion of their brachial plexus, resulting in loss of elbow flexion. Their mean age at the time of the original accident was 27 years (range 16-50 years) and at the time of muscle transfer 35 years (range 22-56 years), with a mean observation period of 20 months (range 6-51 months). In 16 patients, a neurosurgical procedure had been performed after the trauma, and in 22 patients other reconstructive operations had been done. Transfer of the forearm flexors and extensors resulted in active elbow flexion with a mean of 94 degrees (range 70-130 degrees ). After triceps to biceps transposition a mean of 109 degrees (range 70-140 degrees ) was reached. A mean deficit of passive extension of 12 degrees (range 0-30 degrees ) remained after the Steindler procedure, and of 5 degrees (range 0-10 degrees ) after triceps to biceps transposition. Two complications occurred with the Steindler procedure. The transfer of the triceps muscle to the tendon of the biceps and the transfer of the forearm flexors or extensors on loss of elbow flexion, therefore, resulted in adequate movement and strength. Both procedures involve operating close to the elbow joint and had minimal complications. The triceps to biceps transfer is particularly suitable for co-contraction of triceps and biceps.

Accidents, Traffic↗
PubMed2002

Arthroscopic anterior shoulder stabilization: combined multiple suture repair and laser-assisted capsular shrinkage.

The results of laser-assisted capsular shrinkage (LACS) in combination with arthroscopic refixation of the capsulolabral avulsion are compared to those of an arthroscopic Bankart repair alone. In a prospective study, an arthroscopic LACS in combination with a multiple suture capsulolabral refixation according to Caspari and Savoie (Am. J. Sports Med. 12 (1984) 283) was performed from July 1997 to April 1999 on 22 nonselected patients. The clinical results were compared to those of 20 patients following anterior shoulder stabilization according to Caspari without LACS from January 1992 to June 1997. The average follow-up was 59 (21-81) months for the Caspari only and 24 (7-48) months for the Caspari + LACS-group. The observed redislocation rate was reduced to 5% (1/22) through the additional capsular shrinkage, from the initially observed 25% (5/20) of the Caspari only group. A total of 82% of the patients with additional laser shrinkage had a "very good" or "good" outcome when evaluated by Young and Rockwood (J. Bone Joint Surg.73 A (1991) 1) shoulder score, compared to 50% after capsulolabral repair alone. The data show that a capsulolabral repair in combination with LACS provides significantly better clinical results and a lower recurrence rate than the capsulolabral repair alone.

Adult↗
PubMed2002

Osteotomy of the humerus to improve external rotation in nine patients with brachial plexus palsy.

Malfunction of the infraspinatus muscle and teres minor muscle illustrate the typical clinical picture in patients with brachial plexus palsy. The arm hangs down in an inwardly rotated position and elbow flexion is hindered by striking of the lower arm against the thorax. Between 1995 and 2000, we have done external rotational osteotomy of the humerus for nine patients with brachial plexus palsy. The mean age of the patients at the time of operation was 29 years (range 15 to 42). The mean follow-up time was 24 (6 to 69) months. Preoperatively, the patients all had appreciable deficits of external rotation (mean deficit 37 degrees, range 10 degrees to 70 degrees). As a result of osteotomy, external rotation was improved in all patients, the mean increase being 42 degrees (range 25 degrees to 60 degrees). All patients were subjectively content with the improved position of the arm and its function. They were able to move their hands to their faces without striking the lower arm against the chest on elbow flexion, or without compensatory evasive movement of the shoulder.

Adolescent↗
PubMedDate not supplied

Primary stability of shoulder arthrodesis using cannulated cancellous screws.

There are no biomechanical studies available concerned with the primary stability of shoulder arthrodesis. The aim of our biomechanical investigations was to ascertain a minimal material combination with high primary stability for shoulder arthrodesis. For that purpose, the primary stability of 6 different forms of screw arthrodesis was investigated under the stress of abduction, adduction, anteversion, and retroversion. The mean values of the screw arthrodeses were compared with those of a 16-hole plate arthrodesis. All tests were carried out on 24 human specimens without destruction by use of a materials testing machine. The most stable form of screw arthrodesis for the load directions of abduction, adduction, anteversion, and retroversion results from a specific configuration of screws comprising 3 horizontal humeroglenoid screws and 3 vertical acromiohumeral screws (318.5 +/- 99.0 N). For three forms of arthrodesis, each with 3 humerus-glenoid screws (299.9 +/- 95.4 N), no significant difference (P = .530) was found compared with a 16-hole plate arthrodesis (293.4 +/- 89.3 N). The plate arthrodeses only achieved higher power values on abduction and adduction stress in comparison with screw arthrodesis with 3 humerus-glenoid screws. The difference was insignificant. Because arthrodesis with 3 humerus-glenoid screws was significantly more stable on stress of anteversion and retroversion, this particular screw arthrodesis is considered superior to plate arthrodeses. The use of the most stable form of screw arthrodesis may reduce nonunion.

Adult↗
PubMedDate not supplied

Shoulder arthrodesis: indications, technique, results, and complications.

Complications after shoulder arthrodesis are frequent. Through results and comparisons with the literature, the presented article analyzes the correlation of complications with the specific operative techniques, indications, and postoperative treatment. Between 1964 and 2001, a total of 43 cases of shoulder arthrodesis (13 screw and 30 plate arthrodeses) were performed and then analyzed after a mean of 6.7 years (range, 0.5-36 years). Surgery was carried out on 10 female patients (23%) and 33 male patients (77%) with a mean age of 35 years (range, 11-82 years). These patients had the following indications: paralysis (32 [74%]), osteoarthritis or humeral head necrosis (15 [35%]), infection (7 [16%]), and persistent shoulder instability (6 [14%]). The extent of active movement after arthrodesis was 56 degrees abduction (range, 20 degrees - 90 degrees) and 60 degrees forward flexion (range, 20 degrees - 105 degrees), with an increase in the Constant score in all cases, from a mean of 27 points preoperatively to 57 points postoperatively (difference, 30 points). The patients rated the outcome of surgery as excellent, good, or satisfactory in 91% of cases. Complications after shoulder arthrodesis were noted in 12 of 43 patients (28%). The most frequent complications after screw/plate arthrodesis included pseudarthrosis, 2 (15%)/3 (10%); infection, 1 (8%)/4 (13%); and fracture of the humerus, 0/4 (13%). No specific judgment can be attributed to the different osteosynthesis techniques used in shoulder arthrodesis, either in the cases presented at our clinic or in the literature. Pseudarthrosis appeared to be less frequent in cases of plate arthrodesis compared with screw arthrodesis. However, the application of plates resulted more often in infection, postoperative fractures of the humerus, and the necessity for removal of material. Particularly in patients with paralysis, a shoulder arthrodesis resulted in an improvement in postoperative active function and presented a suitable operative option.

Adolescent↗