[Pathomechanical aspects of intra-articular calcaneus fractures. Typing, grading and surgical therapy]. / Die Pathomechanik der intraartikulären Calcaneusfrakturen. Typisierung, Graduierung und operative Therapie.

The forces to produce fractures of the os calcis are combined compression and shear under a cranio-caudal impulse of 10-40 kN and a short time of stroke about 10-40 ms. The main patterns in biomechanics of calcaneal fractures are the time of stroke and the geometrical position of the foot in the moment of impact. Furthermore individual structural changes of the calcaneal cancellous bone, age, diseases as Diabetes mellitus and vascular obliterations are to be respected. Operative treatment of these fractures needs an understanding of the pathomechanism of the intracalcaneal shear-tension-forces. With plantarflexion of the foot combined with vertical forces within 40 ms to the anterior talocalcanear facette impact-fractures of the anterior part can be expected. These forces develop a posterior directed shear tension parallel to the axis of the os calcis, dividing the bone horizontally in two parts (Typ A, 44-56%), well-known as tongue-type fracture. Compression of the posterior talo-calcaneal joint leads to an impact of this structure producing the joint depression type within about 30 ms in dorsoflexion of the foot (Type B, 42%) together with sagittal shear fractures. High-energy forces are supposed to produce the so-called primary fractures of the sustentacular process in about 10 ms in a supinated position of the foot (Type C, 2-10%); these fractures represent in cases of dislocation an indication for open reduction and internal fixation. In our own experience with 45 cases in 35 patients using the lateral or/and medial approach no infection happened. Palmer's lateral approach was preferred.

[Kinematics of the pelvis. Grading and pathomechanical classification of injuries of the pelvic joints and kinematic and clinical consequences of surgical management]. / Die Kinematik des Beckens. Graduierung und pathomechanische Einteilung der Beckenfugenverletzungen und die kinematischen und klinischen Konsequenzen ihrer operativen Versorgung.

The concept of kinematics as an idea basic to the operative and non-operative treatment of pelvic trauma, whether a fractures or a pelvic joint dislocation, is gaining ground in thinking and in technical management. The human pelvic ring may be interpreted by kinematic aspects as a three-bar linkage moving with three bony links (sacrum and both ossa coxae), (n = 3), in three real joints (symphysis pubis and both sacroiliac joints, (g = 3), as a transformer of great forces into small movements, and as a halter under periodic oscillating femoral impulses. The closed kinematic chain of the symmetric pelvic girdle possesses eight degrees of freedom (sigma g f = 8) subject to two external parameters of influence (F = 2), the gravity exerted by the trunk acting on the sacrum as a driving link caudally and ventrally, jointly creating a ring tension inside the pelvis. The guided linkage allows synthesis of a kinematic number and a positive movement equation in accordance with the spatial kinematic rule: F = 6(n-1)-6g + sigma g f = 2. This formula is applied to the investigation of all possible of pelvic joint dislocations types and fractures, and different forms of surgical treatment are described.(ABSTRACT TRUNCATED AT 250 WORDS)

[kinematic consideration of the shoulder girdle and its consequences on common surgical methods]. / Kinematische Betrachtung des Schultergürtels und deren Konsequenz auf verbreitete Operationsverfahren.

Motility of the upper extremities is the sum of movements of an open kinematic chain made up of the hands and the lower and upper arms in the humero-scapular joints which are integrated in the closed kinematic chains of the bilateral symmetrical shoulder girdles. Each shoulder girdle assembles three kinematic links (scapula, clavicle, hemithorax), with three joints (sternoclavicular, acromioclavicular, thoraco-scapular), creating a three-bar linkage. This linkage may be characterized as an effective transformer of motion with 11 degrees of freedom ensuring wide ranges of motions. This motion-transformer acts strictly as a guided linkage, allowing a precise reference between initial motion and functional result. The operative transfixation of acromioclavicular joints in the case of either dislocation or arthrodesis, also of the sternoclavicular joint reduces the degree of kinematic freedom from 11 to 8 and alters the shoulder as a motion-transformer into a rigid girdle with a variable length of support, with degeneration of the shoulder linkage. Surgical treatment of acromioclavicular dislocation with coraco-clavicular fusion using a screw as described by Bosworth produces osseus strain and a girdle under twofold static in determination (F = -2) with pressure forces causing bone deformation, loosening of the screw and fatigue fractures. This operation therefore cannot yet be recommended. Additional cadaver experiments with means of strain gauge cells have shown that lengthening of the clavicle by 0.5 cm increases the forces transmitted from the elevated arm to the hemithorax by 16%. Shortening of the osteotomized clavicle by only 1 cm leads to an increase of these forces by about 40%.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of prolonged fluoride therapy for osteoporosis: bone composition and histology.

To examine the long-term effects of fluoride therapy in osteoporosis, we obtained iliac crest biopsies from 11 osteoporotic patients 6 to 12 years after they had started fluoride therapy. Although basal biopsies were not obtained, nine subjects had been biopsied 4 years prior to the second biopsy. In addition, 4 subjects had stopped fluoride therapy prior to the second biopsy. Biopsy samples were divided and analyzed: (a) histomorphometrically for bone formation and mineralization; and (b) for mineral content. Parameters of bone formation were increased in the first biopsy of all patients; they remained elevated in the second biopsy of subjects still receiving fluoride, but decreased to normal values in subjects who stopped fluoride therapy. Parameters of mineralization (i.e., osteoid width and osteocytic osteoid) were elevated in the first biopsy, but had decreased in the second biopsy whether fluoride was stopped or not. There was no woven bone in these biopsies. Bone mineral content, whether measured as density or by summation of the individual ions (% mineral), was higher than normal in all subjects, whether or not they were still receiving fluoride. These results suggest that prolonged fluoride therapy of osteoporosis continues to stimulate bone formation, but does not cause a progressive mineralization defect. Mineral content is acutely increased following fluoride therapy, and persists after therapy is discontinued.

Low molecular weight proteinuria exacerbates experimental ischemic renal injury.

To determine whether tubular reabsorption of low molecular weight proteins (LMWPs) alters ischemic tubular injury, rats were infused with 25 mg of lysozyme (isoelectric point (pI) 11.3), cytochrome C (pI 10.6), ribonuclease (pI 8.7), or myoglobin (pI 7.0), and during this time 25 minutes of bilateral renal artery occlusion (RAO) was induced. RAO control rats received either saline or 25 mg of albumin. Renal injury was assessed 24 hours later by blood urea nitrogen, creatinine, and histology. Lysozyme, ribonuclease, and myoglobin each exacerbated ischemic damage (increased tubular necrosis, cast formation, azotemia), but to comparable degrees (e.g., blood urea nitrogen range 75 +/- 8 to 100 +/- 5 mg/dl versus controls, 29 +/- 2 to 36 +/- 7; p less than 0.01). Rendering lysozyme anionic (pI 4.5) by succinylation did not diminish its acute renal failure-potentiating effect. Cytochrome C which is freely filtered but poorly reabsorbed had a minimal impact on the ischemic process. Infusion of LMWPs did not alter blood pressure, renal blood flow, or induce renal injury in the absence of RAO. During a sublethal ischemic event (10 minutes of RAO) LMWP infusion exacerbated proximal tubular luminal membrane damage before an adverse effect on other critical determinants of cell integrity were apparent (adenine nucleotide pools, oxidant stress). We conclude that endocytic LMWP reabsorption by proximal tubules can exacerbate superimposed ischemic tubular necrosis independent of any direct nephrotoxic protein effect. This action is not influenced by protein isoelectric point and appears to be mediated by a primary intensification of ischemic luminal membrane damage.

The role of skeletal calcium deficiency in postmenopausal osteoporosis.

A previous study of iliac crest composition identified skeletal calcium deficiency in 25% of 56 postmenopausal osteoporotic patients evaluated prior to the use of stanozolol or calcitonin. This report is a follow-up of biopsy data after 2 years of treatment with drug or placebo in 31 patients, 11 of whom had skeletal calcium deficiency. The study diet, consisting of 1 g elemental calcium plus 400 U Vitamin D, repaired the skeletal calcium deficiency in all patients, treated and untreated alike. Total body calcium (TBC) results were influenced by separation into calcium deficient and normal mineral groups, apparent treatment response being observed largely in patients with calcium deficiency. It is suggested that if all postmenopausal women ingested 1 g elemental calcium plus 400 U Vitamin D daily, skeletal calcium deficiency in osteoporosis would disappear as a problem. Meanwhile, it is important to recognize that repair of calcium deficiency is an important variable capable of influencing bone response to therapy and the evaluation thereof.

Effects of dietary alteration of bicarbonate and magnesium on rat bone.

To study the effects of bicarbonate and magnesium on bone, mild acidosis and/or hypermagnesemia were produced in growing rats by feeding ammonium chloride and/or magnesium sulfate. Bone composition, quantitative histomorphometry, and mineral x-ray diffraction (XRD) characteristics were measured after 6 wk of treatment. The results demonstrated that both acidosis (decreased HCO3) and hypermagnesemia inhibited periosteal bone formation, and, when combined, results were summative; and the previously observed in vitro role of HCO3- and Mg2+ as inhibitors of crystal growth were confirmed in vivo. XRD measurements demonstrated that decreased plasma HCO3 resulted in larger crystals and increased Mg resulted in smaller crystals. However, the combined XRD effects of acidosis and hypermagnesemia resembled acidosis alone. It is postulated that the final composition and crystal structure of bone are strongly influenced by HCO3- and Mg2+, and the effects are mediated by the combined influence on both osteoblastic bone formation and the growth of hydroxyapatite.

[Biomechanical analysis of the medullary bone nail and its locking]. / Biomechanische Analyse des Marknagels und seiner Verriegelung.

By mechanical definition an intramedullary nail is not a nail but rather a bendable feather, subject to longitudinal tension and to a lesser degree to transverse pressure. Reaming the medullary canal is necessary for centralization of the nail as well as to increase the area of contact with the bone. However, this procedure is detrimental to the bone metabolism and reduces its elasticity against torsional forces. The dynamic locking nail-system is more biologic than conventional nailing and it reduces rotatory instability with the help of additional components, such as transverse screws. Only static locking allows true static weight bearing with crutches, but not dynamic mobilisation. Nails with conventional strength and in leaf of trefoil formation are superior to other designs. However, an improved angle in the proximal locking is suggested, as this would allow for a three to four times greater weight bearing.

[Comparative implant analysis in the operative treatment of unstable per- and subtrochanteric femoral fractures and results of 300 osteosyntheses with the 130 degree double T plate]. / Vergleichende Implantatanalyse zur operativen Behandlung instabiler per- und subtrochanterer Oberschenkelfrakturen und die Ergebnisse von 300 Osteosynthesen mit der 130 degrees-Doppel-T-Platte.

We have found that the 130 degrees-Double-T-Plate, when used to repair unstable intertrochanteric femoral fractures in patients in the eighth decade, where high morbidity (92%), osteoporosis and immobility is common, lowers the postoperative complication rate (8,5%), mortality rate (12%) hospital course (means = 24 days) and, last but not least, the total cost of medical care. The biomechanical superiority of these implants over others was shown by comparing moments of inertia, elasticity, bending strength, load capacity and spring constant. In 300 cases of unstable intertrochanteric femoral fractures treated with the 130 degrees-Double-T-Plate, 79% yielded very good to good results, 11% satisfactory results and 10% poor results.

[Biomechanics of intramedullary nailing and its interlocking]. / Zur Biomechanik des Marknagels und seiner Verriegelung.

Mechanically an intramedullary nail cannot be conceived of as a nail but rather as a bendable feather subject to longitudinal tension and, to a lesser degree, to transverse pressure. Reaming the medullary canal is necessary for centralizing of the nail as well as for increasing the area of contact with the bone. However, this procedure is detrimental to the bone metabolism, thus reducing its elasticity against torsional forces. The dynamic locking nail-system is more biologic than conventional nailing, with rotatory instability being reduced by additional components, such as transverse screws. By applying static locking only true static weight bearing with crutches, will be ensured but no dynamic mobilisation. Nails with conventional strength and in trefoil leaf formation are superior to other designs. However, an improved angle in the proximal locking is suggested, as this will allow the weight bearing to be increased three to four times.

[Stable osteosynthesis of unstable per- and subtrochanteric femoral fractures using the 130 degrees double-T plate]. / Die belastungsstabile Osteosynthese instabiler per- und subtrochanterer Oberschenkelfrakturen mit der 130 grade-Doppel-T-Platte.

Operative treatment of instable inter- and subtrochanteric fractures with a new 130 degrees-double-T-plate allowed, in spite of high-risk patients (age x=81 to 84 years, multimorbidity 92%), full maximum load by the third day after operation and a shorter time of hospitalization of 22.5 days. Mortality rate came up to 9%. Load experiments showed that the double-T-profiled 130 degrees-plate with increased lateral moment of resistance could support a weight five times greater than that supported by 130 degrees-implants with transversal blades or DHS-screws. In addition, the double-T (I-Beam) profiled 130 degrees-angled-plate had a resistance to bending two-and-a-half times greater than the hip compression screw from Pohl and has demonstrated its marked clinical success. Follow-up made in 256 patients for 6 to 66 months after double-T-plate osteosynthesis showed good results in 82.2% of the patients satisfied with the outcome of surgery, 13.9% needed two crutches and found the result achieved poor. Only 3.9% of all patients achieved no walking capability.

Bone matrix and mineral abnormalities in postmenopausal osteoporosis.

Iliac crest biopsies from 56 postmenopausal osteoporotic females with spontaneous compression fractures and decreased total body Ca were compared to similar tissue from 48 normal controls. Biopsies were analyzed for bone density, Na, Ca, Mg, P, Co3, and hydroxyproline (OH-P). From the results OH-P/matrix, % mineral, and the ion content of the mineral were calculated. osteoporotic subjects showed decreased bone density, % mineral in bone, and OH-P in the bone matrix. Within the mineral, CO3 and Ca/P were decreased, while Na and Mg were increased. Statistical analysis showed that matrix OH-P and % mineral varied independently, and therefore the patients were separated into 4 subgroups: Group Ia: decreased matrix OH-P with normal % mineral (n = 9), Group Ib: decreased matrix OH-P with decreased % mineral (n = 5), Group IIa: normal matrix OH-P with normal % mineral (n = 33), Group IIb: normal matrix OH-P with decreased % mineral (n = 9). Decreased % mineral was associated with decreased bone density and an increase in Na and Mg in the mineral, which suggests skeletal Ca deficiency. Decreased matrix OH-P was associated with decreased bone density and, in the low % mineral group, with decreased mineral CO3 and Ca/P, suggesting a mineral of decreased mean crystal size. When both abnormalities coexisted (Group Ib), the greatest reduction in total body Ca was seen. Patients with normal matrix and normal % mineral (Group IIa) still had decreased bone density. The results suggest that in a large, clinically homogeneous population of postmenopausal osteoporotic women, 4 subgroups can be identified by differences in chemical composition of iliac crest biopsies.

[Surgical treatment of instable per- and subtrochanteric femure fractures with the 130 degrees double-T-plate. Clinico-experimental report]. / Die operative Behandlung instabiler per- und subtrochanterer Oberschenkelfrakturen mit der 130 degrees-Doppel-T-Platte. Klinisch-experimenteller Bericht.

1. Operative treatment of instable inter- and subtrochanteric fractures with a new 130 degrees double-T plate allowed, in spite of high-risk patients (age mean = 85 years, multimorbidity approximately 92%), full maximum stress by the third day after the operation and a shorter time of hospitalisation of 22.5 days. Lethality was 12.2%. - 2. Load experiments showed that the double-T-profiled 130 degrees plate with increased lateral moment of resistance could support a weight five times greater than that supported by 130 degrees implants with transversal blades, and had a resistance to bending two-and-a-half times greater than hip compression screws. In an 'intertrochanteric' position the plate could carry 3000 N and in a 'subtrochanteric' position 1000 N without permanent deformity. - 3. A review was carried out in 62.6% of the patients 6-32 months after double-T-plate osteosynthesis. Acceptable results were revealed in 80.7%. Of the 98 patients reviewed 44% had complete freedom of movement, 34.6% walked with a stick, 15.4% required crutches and 6% were unable to walk.

Normal maturational changes in bone matrix, mineral, and crystal size in the rat.

Normal rat bone maturation has been studied using biochemical methods and hydrazine separation of matrix and mineral for X-ray diffraction. In the bone, the amount of mineral increases between 4 and 22 weeks of age, while in the matrix, the ratio of noncollagenous protein to collagen progressively decreases. In mineral, in the absence of serum ion changes, growth in mean crystal size appears to be the determinant of the changing ratios of calcium, magnesium, carbonate, and phosphorus, and of the increasing mineral density.

Role of calcium in bone maturation arrest after thyroparathyroidectomy in the rat.

Thyroparathyroidectomy in the rat results in decreased plasma calcium and magnesium and increased phosphorus. The associated bone changes are decreased calcium, hydroxyproline, carbonate, and wholebone density. Bone magnesium, sodium, mineral density, and percent crystallinity are increased. The delayed matrix formation and mineralization previously identified by histologic techniques are herein characterized by direct measurement as arrest of the normal increase of hydroxyproline/matrix and percent mineral. The bone mineral present is of high density and x-ray-diffraction crystallinity, suggesting a decrease in the mineralization front high in the amorphous phase and/or small nondiffracting crystalloids. The chemical studies reveal that in the absence of available Ca, Mg and Na are substituted, and CO3 is decreased. The restoration of these plasma and bone abnormalities to normal by a diet high in CaCO3 adds further emphasis to the essential role of Ca in bone cell function.