[Trigger points - Diagnosis and treatment concepts with special reference to extracorporeal shockwaves]. / Triggerpunkte - Diagnose und Behandlungskonzepte unter besonderer Berücksichtigung extrakorporaler Stoßwellen.

The 70-year-old trigger point theory has experienced a growing scientific confirmation and clinical significance as a consequence of recent muscle pain research. The trigger point pain formation is caused by high levels of vasoneuroactive substances. Depending on intensity and duration of the muscle stimulus the central pain processing is modified and leads to characteristic referred pain patterns. The most effective conventional forms of treatment are aimed at a direct mechanical manipulation of the trigger point as are new forms of therapy with focused and radial shockwaves. By using high pressures the focused shockwaves in particular are suitable to provoke local and referred pain and thus simplify the trigger point diagnosis. The empirically found therapeutic effect of shockwaves on muscles is hypothetical and can be explained in analogy with validated reactions of shockwaves in non-muscle tissues. Overall, the shockwave therapy on muscles represents a confirmation and extension of the existing trigger point therapy. It seems to be suitable for treating functional muscular disorders and myofascial pain syndromes within the locomotor system.

[Pyrost, a spongious, mineral bone substitute. Experimental bases and 13-year clinical experience in over 1000 cases]. / Mineralisches, spongiöses Knochenersatzmaterial Pyrost. Experimentelle Grundlagen und 13 Jahre klinische Erfahrung bei über 1000 Fällen.

In different animal investigations Pyrost demonstrated osteoconductive and osteostimulative effects. In ectopic tissues and especially in conditions of low osteogenetic potency, the combination of Pyrost and autogenic bone marrow effects bone formation. In a clinical prospective study, Pyrost was implanted in 1117 cases in the following indications: Donor site defects after bone transplantation, bone defects after tumor resection, revision of THA, acetabuloplasty, fracture treatment, pseudarthrosis and lengthening osteotomy, spondylodesis. In 87.3% the regeneration of the bone defects was complete, in 8% a partial regeneration was found. Excessive bone formation took place in 2.7%, insufficient regeneration in 2.0% in cases of instability or infection. According to the clinical results Pyrost is a suitable bone substitute in small bone defects and it is a valuable completion to the autogenic bone graft in large defects. In disadvantageous bone bed Pyrost has to be augmented with bone marrow and in large segmental defects the combination with autogenic bone grafts is recommendable. Presupposition for the application of bone substitutes like Pyrost in large defects is a sufficient primary stability of the bone bed. The application in infected tissue is not favorable.

[Cruciate ligament injuries with knee joint effusion--why can the Lachman sign not be elicited?]. / Kreuzbandverletzung mit Kniegelenkserguss--weshalb ist das Lachman-Zeichen nicht auslösbar?

In acute anterior cruciate ligament (ACL) lesions with effusion of the knee joint it is often difficult to realize a positive Lachman sign. It was suggested that the tension of the joint capsule may reduce tibial displacement although the ACL is completely disrupted. In 10 cadaver knee joints the ACL was dissected and the capsule was closed again. By a canula the knee joints were filled with isotonic saline solution in steps of 20 ml up to 100 ml. Before and after dissection of the ACL and during filling the joint we measured the anterior tibial displacement by use of the MEDmetric KT 1000 arthrometer. In a second series we examined 5 patients with acute effusion of the knee joint before and after puncture of the effusion. We detected the electromyographic activity of the quadriceps muscle end and the hamstrings during the KT 1000 test and patellar reflex. In the cadaver tests we found no reduction of the anterior tibial translation while filling the joint with saline solution. The electromyographic examinations showed a reflectory action in the quadriceps muscle and in the hamstrings when the Lachman test was performed. In the quadriceps muscle the electromyographic amplitude was reduced after puncture; the hamstrings showed a drastically reduced amplitude and duration of the signal. When patellar reflex was performed we recorded an electromyographic action in both muscle groups, too. Puncture could only reduce the signals of the hamstrings. Our results suggest that the reduction of the anterior drawer and the Lachman test in acute effusion is caused not mechanically by the tension of the capsule but by a reflectory muscle action of the hamstrings.

Ceramic femoral head fractures in total hip arthroplasty.

A failure analysis was performed of 4341 alumina ceramic heads articulating with 2693 alumina ceramic and 1464 polymer sockets implanted over 20 years (1974 to 1994). From 1974 to 1982, a mushroom shaped head with ceramic neck was used in 1069 cases, and from 1982 to 1994 a ball type head was used in 3272 cases. In the ceramic/ceramic cases, the average followup was 11 years, and in the polymer pairing cases, the average followup was 6 years. In ceramic self pairing with the mushroom shaped head, the fracture rate was 0.4% (5 of 1069). With the ball type head, the fracture rate was 0.06% (1 of 1763). In articulation with polymer sockets, only 1 head fracture occurred (0.07%). In the group of cases with ceramic/ceramic pairing, the reason for fracture was direct trauma in 4 cases, recurrent neck impingement in 2 cases, and fatigue failure in 1 case. The only case with ceramic head fracture in polymer pairing also was caused by direct trauma. Fractures of the alumina ceramic heads cannot be avoided, but the use of ball type neckless heads brought the fracture rate close to 0. Under the aspect of material safety, it seems to be possible to use the great advantage of the superior low wear of the alumina/alumina couple with negligible fracture risk.

[Experimental studies on the role of intramedullary alignment rods in the etiology of fat embolisms in knee endoprostheses]. / Experimentelle Untersuchungen zur Rolle des intramedullären Führungsstabes bei der Entstehung der Fettembolie in der Knieendoprothetik.

Fat embolism syndrome (FES) during implantation of an uncemented resurfacing type of total knee replacement is the leading cause of postoperative mortality. A possible explanation might be the insertion of a solid intramedullary alignment rod, resulting in an intrafemoral pressure increase. On 45 cadaveric human femora we measured the resulting intramedullary pressure during insertion of three different alignment rods: a solid rod and a hollow shaped guiding rod, both 10 mm in diameter, and a fluted alignment rod of 8.5 mm in diameter. The highest intramedullary pressures occurred after placement of a solid 10 mm alignment rod (3.77 +/- 0.44 bar), followed by a fluted 8.5 mm rod (2.53 +/- 0.28 bar). In both cases, the increased pressure led to an extrusion of bone marrow contents through the venous system of the proximal femur. The least increase occurred after insertion of a hollow shaped alignment rod (0.26 +/- 0.03 bar) without any fat extrusion. Our study confirms the hypothesis that insertion of solid intramedullary alignment rods during preparation of the femoral shaft results in a dangerous pressure increase, so that embolization can occur. To minimize the risk of a FES, instruments should be modified in a manner, that only hollow shaped alignment rods are used.

Chondropathia patellae and knee muscle control. An electromyographic study.

The activity of knee-related muscles was registered via exercising on a bicycle ergometer by 17 patients with clinically diagnosed chondropathia patellae. M. quadriceps activity was shorter and the hamstring activity longer in the chondropathy group compared with a matched healthy control group. The changes in m. quadriceps occurred to an almost equal extent in lateral and medial sections. In five patients with unilateral complaints, the electromyographic changes were nevertheless noted on both sides. The study shows that chondropathia patellae involves a change in muscle control affecting not only the knee extensors but also the hamstrings. Through the changed innervation pattern the coactivation phase, i.e. the phase of simultaneous activation of knee flexors and extensors at the end of the extension phase, takes place at a higher angle of flexion. Physiotherapy should involve all knee-related muscles and should include not only isometric but also dynamic exercises.

[Clinical relevance of tunnel position and interference screw location after replacement-plasty of the anterior cruciate ligament with a patellar ligament transplant]. / Klinische Relevanz von Bohrkanalposition und Interferenzschraubenlage nach Ersatzplastik des vorderen Kreuzbandes mit Ligamentum-patellae-Transplantat.

Fifty-eight patients had a prospective follow-up examination 1 year after arthroscopic ACL replacement. Stability measurement was done using a KT-1000 arthrometer. The side-to-side difference was less than 2 mm in 40 patients, 2-4 mm in 11 patients and more than 4 mm in 7 patients. The position of the tibial and femoral tunnels and interference screw was measured from the postoperative X-ray. The positions of screws and tunnels were highly variable. However, there was no statistical correlation between the position of the femoral interference screw and stability measurement or between the position of the femoral interference screw and flexion contracture or between the position of the tibial interference screw and the extension contracture. However, out of six patients with the femoral tunnel in an extremely anterior position (> 20 mm anterior of the over the top position), only one patient had a stable joint (< 2 mm difference in KT 1000 with 89 N anterior shear load) at follow-up. A screw divergence of more than 10 degrees was found in 18 patients. A tibial interference screw with more than 30 degrees of divergence was seen in seven patients. The primary fixation strength of the bone block could be diminished in these cases. This may have an impact on the early rehabilitation protocol.

[Proprioceptive deficit following cruciate lesions--afferent disorder or compensatory mechanism?]. / Propriozeptives Defizit nach Kreuzbandschädigung--afferente Störung oder kompensatorischer Mechanismus?

It was suggested that the ACL has not only mechanical functions but also acts as proprioceptive organ. In cruciate deficient knees pathological patterns of muscle control were found. These findings could be caused by a disturbed afferent signal from the disrupted ACL or by secondary changes in muscle innervation, which shall protect the instable knee against subluxation. 33 patients with unilateral operative ACL repair (21 cases with primary suture, 12 cases with autogenous ligamentum-patellae-reconstruction; average post op 36.5 yr) were examined clinically and with the KT 1000 arthrometer (MEDMETRIC Inc.). Patients history was evaluated by using the LYSHOLM score. During a cycling task the electromyographic activity was monitored from the thigh muscles (M. vastus lat. and med., lat. and med. hamstrings). In comparison to the ACL deficient patients, we tested 25 healthy subjects of same age and activity level. In the ACL group the following differences to the normals were found: the M. vastus lat. showed a significantly delayed onset, earlier end and shorter duration. M. vastus med. had the same pattern; the delayed begin of activity and the shorter duration were statistically significant. M. biceps femoris showed a significant later onset and shorter duration. So did the medial hamstrings; the differences, however, were not statistically significant. There was no significant difference between operated and healthy leg in the ACL group. By comparing the primary sutures and the ligamentum-patellae-reconstructions no significant differences were found. The instable patients (KT 1000 > 3 mm) of the ACL group showed more distinct differences in the EMG pattern than the patients with stable knee joints.(ABSTRACT TRUNCATED AT 250 WORDS)

[Primary stability of autologous and heterologous implants for intervertebral body spondylodesis]. / Die primäre Belastbarkeit autologer und heterologer Implantate für die interkorporelle Spondylodese.

In this study, we tested the stability of the xenograft SURGIBONE and of human iliac crest graft depending on the donor's bone density. The mean load bearing capacity of SURGIBONE was 4816 N, the compressive strength 32.8 N/mm2. This even exceeds the values given by the producer. Yet in clinical use the material caused problems by collapses or lysis of the graft. According to our results, those failures can not be explained by missing primary stability. Perhaps there is a immunogenic reaction of the host against the remaining protein as it once was proved for the "kielspan"-graft. The iliac crest grafts of donors with normal bone density had a load bearing capacity of 3397 N. Grafts of donors with reduced bone density of less than 60 mg/ml Ca-Equivalent showed reduced load bearing capacities of 2265 N. DEXA (Dual-Energy X-Ray Absorptiometry) seems to be suitable to scan preoperatively the iliac crest graft stability in order to recognize the danger of reduced stability by osteoporosis.

Changes in muscular activity after knee arthrotomy and arthroscopy.

The object of this study was to find out whether an arthrotomy of the knee would damage joint proprioception. Twenty patients who underwent arthrotomy, and 20 patients after arthroscopy, were tested on a modified ergometer and the electromyographic action of their quadriceps and hamstrings recorded. The quadriceps action started later and had a shorter duration (20 ms) after arthrotomy. The differences are statistically significant in intra-individual comparison both for vastus lateralis and medialis, in comparison with the normal group for only the vastus medialis. There were no significant differences in muscle control after arthroscopy. These results are in favor of preferring arthroscopy to arthrotomy whenever possible.

[Biomechanical principles of after-care in replacement of the anterior cruciate ligament]. / Biomechanische Grundlagen der Nachbehandlung der Ersatzplastik des vorderen Kreuzbandes.

The patellar tendon graft replacing the anterior cruciate ligament undergoes histomorphological and biomechanical changes. From literature we can estimate a force of 200 N to be a critical limit of graft load after ACL-plasty in humans. The comparison with the graft loads under various conditions provided the following conclusions: Unlimited passive motion of the knee joint can be done without risk. Early weight bearing is possible. Active extension exercise against gravity could damage the graft in the range of 0 to 20 degrees of flexion in some patients. A rehabilitation protocol has to regard these biomechanical principles. In a prospective study 74 patients underwent rehabilitation according to the protocol described. An extension contracture of more than 10 degrees was seen in 9 patients. In all cases it was due to a notch-impingement or a cyclops. One year after operation 57 patients had a follow up. The side to side-difference in anterior drawer measured with a KT-1000-arthrometer was less than 2 mm in 45 patients. Six patients had difference between 2 and 4 mm. In six patients the difference was more than 4 mm.

[Intramedullary pressure in the femur during boring and nailing with modern compression interlocking nails--risk of fat embolism?]. / Intramedulläre Drücke im Femur bei Aufbohrung und Nagelung mit modernen Kompressions-Verriegelungsnägeln--Gefahr einer Fettembolie?

Fat embolism syndrome occurs in only 0.9-4% of patients with long bone fractures and especially with intramedullary nailing. Earlier publications have shown that intramedullary manipulation, e.g. reaming and nailing, can produce high pressures of up to 1 bar. The design of the new non-slotted interlocking compressions nails seems to increase the pressure in the femoral cavity. We measured the intramedullary pressure during reaming of the marrow cavity and insertion of compression nails (OSTEO), using cadaver femora and a piezo pressure transducer. We simulated a proximal fracture and performed 30 drilling and 20 nailing procedures. On average we detected a maximum pressure of 0.26 bar during drilling and 0.63 bar during nailing. During reaming the pressure increased when the reamer had passed the narrow diaphysis and reached the metaphysis. When the tried to enlarge the femoral canal by pushing and pulling the reamer repeatedly we measured high pressure peaks. During nailing we detected short impulses lasting a few milliseconds. The results show that the new compression nail do not produce higher intramedullary pressure than slotted nails. It is possible to avoid a dangerous pressure level by using a careful operative technique.

Lateral tibial avulsion fractures and disruptions to the anterior cruciate ligament. A clinical study of their incidence and correlation.

Avulsion fractures of the lateral tibial plateau, known as the lateral capsular sign, are increasingly associated with anterior cruciate ligament (ACL) ruptures. This phenomenon, known as the Ségond fracture, is a bony avulsion of the menisco-tibial ligament. Stress, which can lead to an avulsion of this kind, almost always occurs during knee flexion and internal tibial rotation, and in most cases only after damage to the primary ACL stabilizer. Examination of 151 ACL ruptures revealed a Ségond fracture in 9% of patients. Nearly all were caused by sports injuries and, understandably, the accident mechanism always included knee flexion and internal rotation of the tibial. In a similarly large number of other knee injuries without damage to the ACL, only one case of a Ségond fracture was found. This phenomenon, which is easy to detect by radiograph, can thus be regarded as a strong indication of the presence of a ligament injury.