Introduction Literature indicates that following microdiscectomy significant loss of disc height with corresponding recurrent back and/or leg pain may occur. Loss of disc material due to herniations and/or surgery can accelerate degeneration of the disc. NuCore™ Injectable Nucleus is an in-situ curing protein polymer hydrogel which mimics the properties of the natural nucleus. It is intended as an adjunct to microdiscectomy, replacing the natural nucleus lost to herniation and discectomy. The hydrogel is injected as a fluid through the annular defect, and adheres to the surrounding discal tissue as it cures. The material is designed to immediately fill the nuclear void and seal the anulotomy; and, in the long term, prevent recurrent herniation and further degeneration of the disc.

Methods Pre-clinical studies showed the device restores biomechanics, and the material is biocompatible, resistant to expulsion forces, and highly durable under simulated in vivo loading. A multi-center pilot clinical study is underway to evaluate NuCore™ Injectable Nucleus as an adjunct to microdiscectomy. At the time of this writing, the material has been implanted into thirteen patients aged between 23 and 52 years (6 females, 7 males) following a standard microdiscectomy procedure for monosegmental radicular pain non-responsive to conservative treatment. L5/S1 was treated in ten cases and L4/5 in three cases.

Results All surgeries were successfully completed using between 0.3 and 2.6cc of hydrogel, with an average injection volume of 1.2cc. Six patients currently are at twelve months follow-up and four others have reached six months. In all cases, pain subsided as normally expected following standard microdiscectomy. Neurologic evaluation, Oswestry index, SF36 and VAS scores were taken pre- and post-operatively, and at six, twelve, twenty-six, and fifty-two weeks post-op. All measures showed significant improvement. Average ODI scores dropped from 44 preoperatively to less than 10 at 12-month follow-up. Leg pain dropped from an average preoperative score of 6.8 to less than 1.0 at 12-month follow-up. All categories of the SF36 showed substantial improvement over preoperative scores. No patient had any device related complication. MRI assessments confirmed stable positioning of the implants at all time-points, and no recurrent herniations. Analysis of standing plain films indicated improved disc height maintenance relative to published literature, with an average loss of disc height at completed follow-ups of 4.4%.

Discussion To our knowledge, this is the first injectable nucleus replacement to have been implanted as an adjunct to microdiscectomy. Early clinical results indicate that NuCore™ Injectable Nucleus can be reliably used as a nuclear defect-filler. All patients are doing well clinically, and disc height and function appear to be maintained over the course of follow-up. Though early results indicate potential functional benefits, longer term follow-up will be necessary to fully determine the functional benefits of this treatment. Additional clinical studies have been approved to investigate the use of this hydrogel as an early intervention in degenerative disc disease.

Introduction Vertebroplasty and kyphoplasty have been gaining popularity for treating vertebral fractures. Current reviews provide an overview of the procedures but are not comprehensive and tend to rely heavily on personal experience. This paper aimed to compile all available data and evaluate the clinical outcome of the two procedures. The objective was to evaluate the safety and efficacy of vertebroplasty and kyphoplasty using the data presented in published clinical studies, with respect to patient pain relief, restoration of mobility and vertebral body height, complication rate, and incidence of new adjacent vertebral fractures.

Methods This is a systematic review of all the available data presented in peer reviewed published clinical trials (69 papers). Where possible a quantitative aggregation of the data was performed. Data was collected for each study under the headings: general information, participants, intervention, outcomes, complications, and follow-up. Outcome data was collected detailing: pain relief, general health, functional improvements, satisfaction with treatment, and reduction in kyphosis. Complications included: cement leakage (asymptomatic and symptomatic), neurological deficits, cardiovascular, pulmonary and any other clinically relevant complication. Long term follow-up information included all the items recorded under the heading “outcome” with the addition of new fracture details.

Results A large proportion of subjects experienced some pain relief (87% vertebroplasty, 92% kyphoplasty). Vertebral height restoration was possible using kyphoplasty (average 6.6°) and for a subset of patients using vertebroplasty. Cement leaks occurred for 41% and 9% of treated vertebrae for vertebroplasty and kyphoplasty respectively. New fractures of adjacent vertebrae occurred for both procedures at rates that are greater than the general osteoporotic population but approximately equivalent to the general osteoporotic population that had a previous vertebral fracture.

Discussion The pain relief experienced by patients is promising for both kyphoplasty and vertebroplasty in the short term (< 1 year). Leakage of the PMMA is the most common complication and may pose significant danger. Higher leakage rates have been reported for vertebroplasty studies compared to kyphoplasty studies. Particularly kyphoplasty has the ability to reduce the kyphotic angle and restore vertebral height. The critical factor for the restoration of vertebral height would appear to be fracture age.

Minimal-invasive augmentation techniques have been advocated to treat osteoporotic vertebral body fractures (VBFs). Kyphoplasty is designed to address both fracture-related pain as well as the kyphotic deformity usually associated with the fracture. Previous studies have indicated the potential of the technique for immediate pain relief and reduction of vertebral height, but whether this is a lasting effect, has not been well investigated. The current prospective study reports on our experience and the one-year results in 27 kyphoplasty procedures in 24 patients with PMMA for osteoporotic VBFs.

Pain was assessed on a 0–10 VAS. Deformity and reduction of the vertebral body was measured as the angulation between the two endplates on standing lateral radiographs. All parameters were taken pre-op, one day and two months post-operatively and after one year. Multiple regression analysis was conducted to determine the importance of independent factors as predictors of the achieved fracture reduction.

All but one patient experienced pain relief directly following the procedure with a lasting effect after 2 months and also one year in 25 cases. An average vertebral kyphosis reduction of 47.7% was achieved with no loss of reduction after one year. Pain relief was not related to the amount of reduction. The potential for reduction was related to pre-op kyphosis, level treated, and fracture age, but not to the age of the patient.

In this series, kyphoplasty was an effective treatment of VBFs in terms of pain relief and durable reduction of deformity. However, whether spinal realignment results in an improved long-term clinical outcome remains to be investigated.

Vertebroplasty, which is the percutaneous injection of bone cement into vertebral bodies has recently been used to treat painful osteoporotic compression fractures. Early clinical results have been encouraging, but very little is known about the consequences of augmentation with cement for the adjacent, non-augmented level.

We therefore measured the overall failure, strength and structural stiffness of paired osteoporotic two-vertebra functional spine units (FSUs). One FSU of each pair was augmented with polymethyl-methacrylate bone cement in the caudal vertebra, while the other served as an untreated control.

Compared with the controls, the ultimate failure load for FSUs treated by injection of cement was lower. The geometric mean treated/untreated ratio of failure load was 0.81, with 95% confidence limits from 0.70 to 0.92, (p < 0.01). There was no significant difference in overall FSU stiffness. For treated FSUs, there was a trend towards lower failure loads with increased filling with cement (r² = 0.262, p = 0.13).

The current practice of maximum filling with cement to restore the stiffness and strength of a vertebral body may provoke fractures in adjacent, non-augmented vertebrae. Further investigation is required to determine an optimal protocol for augmentation.

Surgical dislocation of the hip is rarely undertaken. The potential danger to the vascularity of the femoral head has been emphasised, but there is little information as to how this danger can be avoided. We describe a technique for operative dislocation of the hip, based on detailed anatomical studies of the blood supply. It combines aspects of approaches which have been reported previously and consists of an anterior dislocation through a posterior approach with a ‘trochanteric flip’ osteotomy. The external rotator muscles are not divided and the medial femoral circumflex artery is protected by the intact obturator externus. We report our experience using this approach in 213 hips over a period of seven years and include 19 patients who underwent simultaneous intertrochanteric osteotomy. The perfusion of the femoral head was verified intraoperatively and, to date, none has subsequently developed avascular necrosis. There is little morbidity associated with the technique and it allows the treatment of a variety of conditions, which may not respond well to other methods including arthroscopy. Surgical dislocation gives new insight into the pathogenesis of some hip disorders and the possibility of preserving the hip with techniques such as transplantation of cartilage.