The Spinebot—A Robotic Device to Intraoperatively Quantify Spinal Stiffness

Degenerative spine problems and spinal deformities have high socio-economic impacts. Current surgical treatment is based on bony fusion that can reduce mobility and function. Precise descriptions of the biomechanics of normal, deformed, and degenerated spinal segments under in vivo conditions are needed to develop new approaches that preserve spine function. This study developed a system that intraoperatively measures the three-dimensional segmental stiffness of patient's spine. SpineBot, a parallel kinematic robot, was developed to transmit loads to adjacent vertebrae. A force/torque load cell mounted on the SpineBot measured the moment applied to the spinal segment and calculated segmental stiffnesses. The accuracy of SpineBot was characterized ex vivo by comparing its stiffness measurement of five ovine specimens to measurements obtained with a reference spinal testing system. The SpineBot can apply torques up to 10 N·m along all anatomical axes with a total range of motion of about 11.5 deg ± 0.5 deg in lateral bending, 4.5 deg ± 0.3 deg in flexion/extension, and 2.6 deg ± 0.5 deg in axial rotation. SpineBot's measurements are noisier than the reference system, but the correlation between SpineBot and reference measurements was high (R2 > 0.8). In conclusion, SpineBot's accuracy is comparable to that of current reference systems but can take intraoperative measurements. SpineBot can improve our understanding of spinal biomechanics in patients who have the pathology of interest, and take these measurements in the natural physiological environment, giving us information essential to developing new “nonfusion” products.

Spine deformities in patients with cerebral palsy; the role of the pelvis

INTRODUCTION

Progressive neuromuscular spinal deformities with pelvic obliquity and loss of sitting balance are typical features of severely affected patients with cerebral palsy. The pelvis represents the key bone between the spine and the lower extremity when it comes to deciding whether and when to operate and if spine or hip surgery first is beneficial. The pelvis can be looked at as the lowest vertebra and as the rooftop of the lower extremities.

BIOMECHANICAL CONSIDERATIONS

To allow for a normal spinal shape, the pelvis needs to be horizontal in the frontal plane and mildly anterior tilted in the sagittal plane, less for sitting and more for standing. Any abnormal pelvic position requires spinal compensation and challenges the equilibrium control of the individual. Both anatomical neighbourhoods - the spine and the hip joints - have to be considered when spinal deformities, hip instability and contractures evolve, in conservative therapy (bracing, physiotherapy, seating in the wheelchair) and when surgical interventions are weighed out against each other.

SURGICAL CONSIDERATIONS

Multiple anatomical factors such as sagittal profile and pelvic orientiation, pelvic transverse plane asymmetries and lumbosacral malformations have to be considered in case the pelvis is instrumented with sacral and iliac screws. Rotational deformities and asymmetries of the pelvic bones make the safe insertion of long screws challenging. Advantages of primary pelvic fixation include correction of pelvic obliquity, especially considering the lever arm of the whole spinal construct. The risk of revision surgery due to progression of distal curves is also reduced. Disadvantages of pelvic fixation include the complexity of the additional intervention, which may result in longer operating times, increased risk of blood loss, infection and hardware malpositioning.

[Etiology and significance of growth disturbances of the spine]

BACKGROUND

The majority of growth disturbances of the spine are acquired and their etiology is still unknown. Both scolioses and sagittal profile disorders are most commonly of idiopathic origin.

ETIOLOGY

The etiology is multifactorial and besides genetic, hormonal and mechanical factors also metabolic components seem to be involved. The risk of progression of an existing deformity is particularly high during the pubertal growth spurt. Accordingly, regular clinical and radiological controls should be carried out in this vulnerable period. Recently, spinal deformities have been classified according to the time of diagnosis rather than according to their etiology, considering the increasing knowledge about the correlation between spinal and thoracic growth and the associated maturation of the lungs. Therefore, the term "early onset scoliosis" considers all deformities of the spine diagnosed before the age of 10 years.

TREATMENT

In the case of failure of conservative treatment options, which have to be applied for as long as possible, definitive spinal fusion surgery should be delayed by the use of growth-sparing surgical techniques, aiming to achieve as normal pulmonary function as possible.

Complex spine deformities in young patients with severe osteogenesis imperfecta: current concepts review

The severity of osteogenesis imperfecta (OI), the associated reduced quality and quantity of collagen type I, the degree of bone fragility, ligamentous laxity, vertebral fractures and multilevel vertebral deformities all impair the mechanical integrity of the whole spinal architecture and relate to the high prevalence of progressive kyphoscoliotic deformities during growth. Bisphosphonate therapy may at best slow down curve progression but does not seem to lower the prevalence of deformities or the incidence of surgery. Brace treatment is problematic due to pre-existing chest wall deformities, stiffness of the curve and the brittleness of the ribs which limit transfer of corrective forces from the brace shell to the spine. Progressive curves entail loss of balance, chest deformities, pain and compromise of pulmonary function and eventually require surgical stabilization, usually around puberty. Severe vertebral deformities including deformed, small pedicles, highly brittle bones and chest deformities, short deformed trunks and associated issues like C-spine and cranial base abnormalities (basilar impressions, cervical kyphosis) as well as deformed lower and upper extremities are posing multiple peri- and intraoperative challenges. Hence, an early multidisciplinary approach (anaesthetist, pulmonologist, paediatric orthopaedic spine surgeon) is mandatory. This paper was written under the guidance of the Spine Study Group of the European Paediatric Orthopaedic Society. It highlights the most pertinent information given in the current literature and various practical aspects on surgical care of spine deformities in young OI patients based on the personal experience of the contributing authors.

Immediate hip spica is as effective as, but more efficient than, flexible intramedullary nailing for femoral shaft fractures in pre-school children

Flexible intramedullary nailing (FIN) is the gold standard treatment for femur fracture in school-aged children. It has been performed successfully in younger children, although Spica cast immobilisation (SCI) has been the most widely used strategy to date.

METHOD

A retrospective analysis was performed between two comparable groups of children aged 1-4 years with a femoral shaft fracture. Two University hospitals, each using specific treatment guidelines, participated in the study: SCI in Group I (Basel, Switzerland) and FIN in Group II (Lausanne, Switzerland).

RESULTS

Group I included 19 children with a median age of 26 months (range 12-46 months). Median hospital stay was 1 day (range 0-5 days) and casts were retained for a median duration of 21 days (range 12-29 days). General anaesthesia was used in six children and sedation in four. Skin breakdown secondary to cast irritation occurred in two children (10.5%). The median follow-up was 114 months (range 37-171 months). No significant malunion was noted. Group II included 27 children with a median age of 38.4 months (range 18.7-46.7 months). Median hospital stay was 4 days (range 1-13 days). All children required general anaesthesia for insertion and removal of the nails. Free mobilisation and full weight bearing were allowed at a median of 2 days (range 1-10 days) and 7 days (range 1-30 days), respectively, postoperatively. Nail exteriorisation was noted in three children (11%). The median follow-up was 16.5 months (range 8-172 months). No significant malunion was reported.

CONCLUSIONS

Young children with a femoral shaft fracture treated by SCI or FIN had similarly favourable outcomes and complication rates. FIN allowed earlier mobilisation and full weight bearing. Compared to SCI, a greater number of children required general anaesthesia. In a pre-school child with a femoral shaft fracture, immediate SCI applied by a paediatric orthopaedic team following specific guidelines allowed early discharge from hospital with few complications.

Greenstick fractures of the middle third of the forearm. A prospective multi-centre study

BACKGROUND

Greenstick fractures suffered during growth have a high risk for refracture and posttraumatic deformity, particularly at the forearm diaphysis. The use of a preemptive completion of the fracture by manipulation of the concave cortex is controversial and data supporting this approach are few.

AIM

Aim of this study was to determine the factors which predispose to refracture and deformities, and to define therapeutic strategies.

METHODS

We prospectively gathered clinical and radiographic data over a period of one year on greenstick fractures of the middle third of the forearm in children as part of a multi-centre study. Endpoint was a follow-up visit at one year. Radiographic deformity, state of consolidation at resumption of physical activities and refracture rate were analysed statistically (ANOVA, Student's t-test and Pearson's chi-square test) with regard to patient age, gender, fracture type, therapy and time in plaster.

RESULTS

We collected the data of 103 patients (63 boys, 40 girls), average age 6.6 years (1.3-14.5 years), the vast majority of whom had a combined greenstick fracture of the radius and ulna. 6.7% of the patients sustained a refracture within 49 days (29-76) after plaster removal. They were significantly older (p=0.017) with a significantly higher incidence of manual completion of the fracture with radiographic signs of partial consolidation (p=0.025). Residual deformities were significantly smaller after completion of the fracture compared to reduction without completion (p=0.019) or plaster fixation alone (p<0.005).

CONCLUSIONS

Completion of a greenstick fracture does not prevent refracture. Nevertheless, it diminishes the extent of secondary deformities in cases where the primary angulation exceeds the remodelling capacity. Prevention of refracture should include a routine radiographic follow-up 4-6 weeks after injury with continuation of plaster fixation in cases of partial consolidation.

Digital imaging data on CD-R: a time trap for orthopaedic surgeons in outpatient clinics

PURPOSE

X-rays are presented on CD-Rs in a digital format with increasing frequency. This technique is potentially more time-consuming for the clinician compared to conventional pictures.

METHODS

Ten sets of six X-rays for each case were prepared in both the conventional way and in digital format on CD-R. The order was randomised. Time in seconds was measured for six experienced orthopaedic residents to present the most recent a.p. view out of a given set. As a precondition, the computer was turned on and the same viewing software was used for all digital sets. The results were compared using a non-linked Student's t-test (significance level P = 0.05).

RESULTS

The presentation of conventional X-rays required 21 s (+/-7.5 s) and of digital X-rays 90 s (+/-27 s), respectively (P < 0.001).

CONCLUSION

In spite of ideal conditions, digital X-rays on CD-R need significantly more time in the orthopaedic clinic. In major centres, patients present with different software and software in other languages, which increase the required time even further. This latter problem will be assessed in another study. This increase of preparation time required by a highly qualified staff member has implications on the economics and logistics and has a negative impact on daily clinical practice. One of the solutions might be that the CD-Rs be given to the registration desk and the data being already prepared when the patient sees the doctor. This can also include it being implemented in the digital system used in the inpatient part of the hospital and, therefore, making any other consultations or second opinions easily accessible.

Marked initial displacement predicts complications in physeal fractures of the distal radius: an analysis of fracture characteristics, primary treatment and complications in 109 patients

BACKGROUND

Factors predicting redisplacement in the cast and early complications in distal radial physeal injuries have not been analyzed before.

PATIENTS AND METHODS

We analyzed 109 consecutive children with displaced physeal fractures of the distal radius treated by manipulation under anesthesia

RESULTS

Acute carpal tunnel syndrome developed in 2 patients. Posttraumatic swelling necessitating trimming, splitting or removal of the primary circular cast occurred in one-sixth of the patients. Half of the fractures healed in malunion despite an anatomic primary reduction in 85% of the cases. According to logistic regression models, marked initial malposition of the fracture (< 50% displacement or < 20% angulation) was an independent risk factor for complications and redisplacement. Non-anatomic reduction of the fracture was an additional independent risk factor for redisplacement.

INTERPRETATION

The risk of an acute carpal tunnel syndrome should be remembered in patients with marked primary displacement of the fracture. To avoid redislocation, pin fixation of the fracture in patients close to skeletal maturity should be considered if there is a marked initial malposition of the fracture, or if fully anatomic reduction cannot be achieved.

Improvement of motor-evoked potentials by ketamine and spatial facilitation during spinal surgery in a young child

Monitoring motor evoked potentials is desirable during spine surgery but may be difficult to obtain in small children. In addition, the recording of reliable signals is often hampered by the presence of various anesthetics. We report the case of a young child whose motor evoked potentials were successfully monitored using a ketamine-based anesthesia and a newly introduced stimulation technique consisting of combined spatial and temporal facilitation.

A South Australian population-based study of congenital talipes equinovarus

The aims of this study were to provide a population-based prevalence for congenital talipes equinovarus (CTEV), to conduct an epidemiological investigation into the risk factors for CTEV and describe associated features. The study used a retrospective case-control design of CTEV notified to the South Australian Birth Defects Register between 1986 and 1996 inclusive, linking characteristics of mother and baby from the perinatal data collection. The prevalence of isolated CTEV was 1.1/1000 total births (n = 231). Four factors were significantly associated with an increased risk of CTEV: maternal Aboriginal race (ORadj = 2.0; 95% CI 1.1, 3.6), male gender (ORadj = 2.4; 95% CI 1.8, 3.2), maternal anaemia (ORadj = 1.8; 95% CI 1.0, 2.9) and maternal hyperemesis (ORadj = 3.6; 95% CI 1.3, 9.8). The prevalence of CTEV associated with another birth defect or syndrome (n = 157) was 0.7/1000 total births. CTEV was associated with specific birth defects and also with oligohydramnios when another birth defect was present.

[Pediatric spinal injuries]

Spine injuries during growth are rare, but in comparison to adults they are more often associated with neurologic impairment. They also may occur without visible injuries in X-rays. The problems of conventional radiologic diagnostics include before all the differential diagnosis between synchondrosis, apophysis and fracture lines. MRI is indicated in case of neurologic deficits without radiologic abnormalities. In principle the fracture types correspond to those seen in adults. In addition growth specific injuries of the end-plates (growth plates) or ring apophysis may occur. Stable compression fractures are treated conservatively. The spontaneous remodelling capacity for posttraumatic deformities decreases with age: in children below the age of ten years the remodelling capacity for posttraumatic kyphosis is excellent whereas deformities in the frontal plane show no or only incomplete remodelling. Unstable fractures and injuries with associated compression of neural structures should be treated conservatively.

[Spondylolysis and spondylolisthesis during growth]

Spondylolysis and Spondylolisthesis present with typical age and activity-related issues: in newborns the pars interarticularis is always intact. Only bipedal ambulators develop spondylolysis, mostly during early childhood. Corresponding to the mechanical etiology, the incidence of spondylolysis is higher in athletes who repeatedly have to hyperextent and rotate their lumbar spine for example gymnasts, javelin throwers etc. Spondylolysis is one of the most frequent diagnosis among adolescents with lumbar back pain. However, most of the people with an interrupted Pars interarticularis (about 6% of the population) never become symptomatic or if they do, they respond very well to conservative treatment (adaptation of physical activity, active physical therapy and bracing). If pain persists in combination with an intact intervertebral disc of the slipped segment, we recommend a direct repair of the Pars interarticularis instead of an intersegmental fusion. Patients with low grade Spondylolisthesis (Meyerding I, II) require repeated radiological follow-up during growth because of the inherent risk of slip progression. If a slip of more than 50% is detected before the end of growth, operative treatment is indicated. High grade olisthesis (Meyerding III, IV) leads to anterior shift of the whole trunk, kyphosis of the slipped vertebra with subsequent compensatory lumbar hyperlordosis and flattening of the thoracic spine. Pelvic flexion is clinically evident. Reduction of the slipped and kyphotic vertebra with correction of the spinal, sacral and pelvic profile is recommended and preferable to simple fusion in situ.

[Spontaneous corrections, growth disorders and post-traumatic deformities after fractures in the area of the forearm of the growing skeleton]

Growth phenomena after paediatric forearm fractures are described. The capacity for spontaneous remodelling of malunions should be primarily considered in the treatment of fractures of the growing skeleton. Thus, unnecessary reductions, anaesthesia and posttraumatic deformities can be prevented. Generally speaking, a high remodelling capacity can be expected in cases of enough remaining growth, proximity to a physis with high activity, and if the main deformity lies in the plane of motion of the nearest joint. It is widely accepted that distal radius and/or ulna fractures are fully remodelled up to the age of 11 to 12 years. However, the remodelling capacity of fractures of the proximal and middle third of the shaft is smaller and less well known. Stimulating growth disturbances at the upper extremities are clinically of minor importance. Growth arrests are rare. Their fateful occurrence is not predictable and not closely related to fracture pattern or amount of dislocation.

Free fat interpositional graft in acute physeal injuries: the anticipatory Langenskiöld procedure

Free fat graft interposition has been used extensively in management of physeal injuries with established growth disturbances. The use of this technique as part of the management of acute physeal injuries has not been reported. Here we report on its application in acute physeal injuries, where it has prevented the formation of an anticipated physeal arrest.

[Screw osteosynthesis in dislocated fractures of the radial condyle of the humerus in the growth period. A prospective long-term study]

Pseudoarthrosis and cubitus valgus as main complications following displaced fractures of the radial condyle in children can be prevented by open reduction and fixation by K wires. However, delayed union and stimulation of the radial physis with condylar overgrowth and varisation of the elbow as well as fishtail deformities of the distal end of the humerus are reported nevertheless. To prevent those growth disturbances all primary and secondary (4-day X-ray control) displaced fractures of the radial condyle, i.e. those with a central gap of more than 2 mm, were prospectively treated by open reduction and osteosynthesis with a metaphyseal lag screw beginning 1974. Sixty-six patients (41 boys, 25 girls) with an average follow-up of 10 years (2-22 years) sustained 28 primary and 6 secondary displaced fractures. In 5 cases a K wire fixation was performed in view of the smallness of the fragment. Two children with conservative treatment following overlooked displaced fractures showed condylar overgrowth and varisation of the elbow. Screw osteosynthesis led to symmetric elbow angles and function in all cases, whereas fishtail deformities could be observed in 8 of 27 children, probably as a consequence of the remaining central fracture instability.

CONCLUSION

Open reduction and osteosynthesis with a metaphyseal lag screw prevents condylar overgrowth in displaced fractures of the radial condyle by guaranteeing fracture healing in anatomic position within 3-4 weeks. However, fishtail deformity can not be prevented by metaphyseal compression only.

[Imported dengue fever following a stay in the tropics]

We report on a tourist returning from Thailand, who presented with classical dengue fever. While in Thailand a 36-year-old Swiss female laboratory assistant suddenly developed fever, devastating headache, retro-ocular pain, myalgia and arthralgia, photophobia, nausea and diarrhea. In addition she suffered from epistaxis, urogenital and skin bleeding, and a morbilliform exanthema. After her return to Switzerland we noted lymphadenopathy and splenomegaly, enanthema and laboratory findings of mild hepatitis, thrombocytopenia and leukopenia. The diagnosis of dengue virus infection was verified serologically. Apart from a long lasting convalescent asthenia we observed restitutio ad integrum within days under symptomatic therapy. Epidemiological clinical and diagnostic aspects of dengue virus infection are discussed.

Proteases and antiproteases related to the coagulation system in plasma and ascites. Prediction of coagulation disorder in ascites retransfusion

To improve the ability to predict the occurrence of coagulation disorders in ascites retransfusion and, in addition, to better define the nature of the coagulation disorder, several proteases and antiproteases were analyzed in ascites and plasma before ascites retransfusion in 17 patients. Plasminogen, alpha 2-antiplasmin, antithrombin III, and fibrin(ogen) degradation products in ascites were significantly altered in patients who later developed abnormal coagulation as compared to those who did not. Only plasminogen and alpha 2-antiplasmin in ascites achieved a sufficient predictive value for the occurrence of coagulation abnormalities. The pattern of the coagulation abnormalities observed strongly suggests fibrinolysis induced by the infusion of plasminogen activators as the cause of the coagulation disorder in ascites retransfusion procedures.

Proteases and antiproteases related to the coagulation system in plasma and ascites--influence of dexamethasone

Fibrinolysis induced by the infusion of plasminogen activators into the circulation has been shown to cause coagulation disorders in ascites retransfusion. Dexamethasone is known to inhibit the synthesis of plasminogen activators by peritoneal macrophages. We therefore assessed its potential in preventing the occurrence of fibrinolysis by injecting 16 mg dexamethasone intraperitoneally in 10 patients 24 h before ascites retransfusion was performed. In addition, the effect of dexamethasone upon the activity or concentration of several proteases and antiproteases related to coagulation in plasma and ascites was analyzed on 15 occasions. An increase of the activity of plasminogen, alpha 2-antiplasmin, and antithrombin III, and in the concentration of alpha 1-protease inhibitor in ascites was induced by the dexamethasone injection. However, the reaction was not identical in all patients. Those patients having an increase of plasminogen activities of 0.6 CTA U/ml or more did not show signs of fibrinolysis during retransfusion. The results obtained indicate that intraperitoneal injection of dexamethasone decreases the concentration of plasminogen activators in ascites and thereby reduces the risk of coagulation disorders during retransfusion procedures. Since the effect is variable and not sustained, assessment of preoperative plasminogen concentrations is mandatory in order to prevent complications.