In orthopaedic spine surgery pedicle screw systems are used for stabilisation of the spine after injuries or disorders. With an percutaneous operation method surgeons are faced with huge challenges compared to an open surgery, but it's less traumatic and the patient benefits with a faster rehabilitation and less traumatic injuries. The screw positions and the required rod dimensions for the stabilising connection between the screws are hard to define without an open view on the operating field. Because of these facts a new smart device based system for rod shape determination was invented. Therefore, an application was developed, which integrates a localiser module to get the position data of the pedicle screws, with help of rigid bodies placed on top of the pedicle screws down-tubes. An algorithm was developed to choose the best fitting rod to connect the pedicle screws with help of calculating the rod length and the rod radius. The system was tested in a test scenario where four pedicle screws were drilled into a wooden plate. The positions of the screws were adjusted to fit a curved and a straight rod. In the test scenario the application chose always the rod correctly.

The key for a successful total hip replacement (THR) and the longevity of the implant is the correct alignment of the acetabular cup which is to be considered as the most critical component. The alignment of the cup is defined with respect to anterior pelvic plane (APP). The APP defines the reference for the anteversion and inclination angles which sets the basis for the correct alignment of the implant. The angle of the plane is created by three distinct anatomical landmarks which are represented by two anterior superior iliac spines (ASIS) and the symphysis pubis. The angle of the APP in respect to the coronal plane defines the pelvic tilt (PT) which can be anterior or posterior. The rotation of the pelvis highly depends on the individual anatomy of the subject. This means that a neutral pelvic tilt (PT) in supine position is rarely observed and also may be dissimilar in standing position. In this paper we present a non-invasiveness and cost-effective prototype for measuring the patient-specific PT under the use of a navigated smart-device based ultrasound system for supporting surgery planning. In view of the non-invasiveness method the system can be used to measure pre- and postoperative pelvic orientation. With the use of an artificial hip reference model different cases were measured. The computed results look very promising with a standard deviation of ±1°.

Purposes

To compare the acetabular component size relative to the patient's native femoral head size between conventional THA (CTHA) approach and robotic-guided THA (RGTHA) to infer which of these techniques preserves more acetabular bone.

Introduction

Accurate component placement in total hip arthroplasty (THA) improves post-operative stability and reduces wear and aseptic loosening. Methods for achieving accurate stem placement have not been as extensively studied as cup placement.

We present to you a match-controlled study assessing co-existing arthroscopic findings during hip arthroscopy in patients with an intraoperative diagnosis of a central acetabular osteophyte (CAO). We feel that this manuscript is both pertinent and timely.

Recent literature has described the entity of central acetabular impingement, in which an osteophyte of the cotyloid fossa impinges against the superomedial femoral head and fovea. The technique for central acetabular decompression has also been described to treat this entity. The primary purpose of this study was to report the prevalence of femoral head articular damage in a matched cohort of patients with and without central acetabular osteophyte (CAO) that was identified during hip arthroscopy. A secondary purpose was to identify the rates of co-existing intraarticular pathology in both patient groups.

Intraoperative data was collected prospectively on all patients undergoing hip arthroscopy at our institution between February 2008 to March 2015,. The inclusion criteria for this study were the presence of a CAO identified during hip arthroscopy for a labral tear and/or femoroacetabular impingement (FAI). Exclusion criteria were revision surgeries, Tönnis grade 1 and higher, and previous hip conditions such as Legg-Calves-Perthes disease, avascular necrosis, and prior surgical intervention. The matched cohort control group was selected based on gender, age within 5 years, body mass index (BMI), and workers' compensation claim, on a 1:3 ratio to patients who underwent hip arthroscopy for a labral tear and/or FAI and did not have a CAO.

The CAO group consisted of 126 patients, which were matched to 378 patients in the control group. The grades of femoral and acetabular chondral damage were significantly different between the two groups (p<0.01).

This study showed that patients with CAO had a significantly higher prevalence of femoral and acetabular chondral damage, size of articular defects on both surfaces and the prevalence of LT tears compared to matched controls.

Background

Preservation of acetabular bone during primary total hip arthroplasty (THA) is important, because proper stability of cementless acetabular cup during primary THA depends largely on the amount of bone stock left after acetabular reaming. Eccentric or excessive acetabular reaming can cause soft tissue impingement, loosening, altered center of rotation, bone-to-bone impingement, intraoperative periprosthetic fracture, and other complications. Furthermore, loss of bone stock during primary THA may adversely affect subsequent revision THA.

Background

Preservation of acetabular bone during primary total hip arthroplasty (THA) is important, because proper stability of cementless acetabular cup during primary THA depends largely on the amount of bone stock left after acetabular reaming. Eccentric or excessive acetabular reaming can cause soft tissue impingement, loosening, altered centre of rotation, bone-to-bone impingement, intra-operative periprosthetic fracture, and other complications. Furthermore, loss of bone stock during primary THA may adversely affect subsequent revision THA.

Parathyroid hormone (PTH) and derivatives such as teriparatide (PTH (1–34)) have gained major attention in recent years in treatment of osteoporosis due to their anabolic action on the bone remodelling cycle. These drugs are currently the only available agents being classified as sole anabolic. Interestingly, action of these agents strongly depends on the way they are administered. While these drugs act catabolically when given continuously, they act anabolically when administered in a pulsatile way. Several hypotheses have been proposed to explain this behaviour. However, so far no agreement as regards detailed underlying biochemical regulation has been made. Parallel to intense experimental research to resolve this problem a few mathematical models have been proposed dealing with this subject. In this paper we propose a novel underlying mechanism for anabolic action of PTH based on mathematical modelling of bone cell population dynamics. Using this model allows us to investigate various hypotheses put forward by bone biologists. Additionally, comparison with other theoretical models proposed in the literature will be made.

The medical treatment of eight patients with paraparesis associated with Paget's disease of the vertebrae is described. Treatment, for 3 to 87 months, with calcitonin or with diphosphonates produced marked clinical improvement in seven of these patients. From this series and a review of 19 additional case reports it is concluded that favourable clinical response is seen in about 90 per cent of patients, and that this may occur very rapidly. Results are as good or better than those obtained by surgical decompression. It seems possible that paraparesis in some cases may be due to diversion of blood supply from the spinal cord to the highly vascular Pagetic bone giving rise to a vascular "steal" syndrome. It is suggested that medical treatment should be used more widely to avoid or delay the need for operation and reduce the risks of recurrence. These patients, however treated, require lifelong follow-up because relapses are common.