In this in vitro study of the
hip joint we examined which soft tissues act as primary and secondary
passive rotational restraints when the hip joint is functionally
loaded. A total of nine cadaveric left hips were mounted in a testing
rig that allowed the application of forces,
Reported rates of dislocation in hip hemiarthroplasty
(HA) for the treatment of intra-capsular fractures of the hip, range
between 1% and 10%. HA is frequently performed through a direct
lateral surgical approach. The aim of this study is to determine
the contribution of the anterior capsule to the stability of a cemented
HA through a direct lateral approach. . A total of five whole-body cadavers were thawed at room temperature,
providing ten hip joints for investigation. A Thompson HA was cemented
in place via a direct lateral approach. The cadavers were then positioned
supine, both knee joints were disarticulated and a digital torque
wrench was attached to the femur using a circular frame with three
half pins. The wrench applied an external rotation force with the
hip in extension to allow the hip to dislocate anteriorly. Each
hip was dislocated twice; once with a capsular repair and once without
repairing the capsule. Stratified sampling ensured the order in
which this was performed was alternated for the paired hips on each
cadaver. . Comparing peak
Objectives. We aimed to further evaluate the biomechanical characteristics
of two locking screws versus three standard bicortical
screws in synthetic models of normal and osteoporotic bone. Methods. Synthetic tubular bone models representing normal bone density
and osteoporotic bone density were used. Artificial fracture gaps
of 1 cm were created in each specimen before fixation with one of
two constructs: 1) two locking screws using a five-hole locking
compression plate (LCP) plate; or 2) three non-locking screws with
a seven-hole LCP plate across each side of the fracture gap. The
stiffness, maximum displacement, mode of failure and number of cycles
to failure were recorded under progressive cyclic torsional and
eccentric axial loading. Results. Locking plates in normal bone survived 10% fewer cycles to failure
during cyclic axial loading, but there was no significant difference
in maximum displacement or failure load. Locking plates in osteoporotic
bone showed less displacement (p = 0.02), but no significant difference
in number of cycles to failure or failure load during cyclic axial loading
(p = 0.46 and p = 0.25, respectively). Locking plates in normal
bone had lower stiffness and
Objectives. The use of two implants to manage concomitant ipsilateral femoral
shaft and proximal femoral fractures has been indicated, but no
studies address the relationship of dynamic hip screw (DHS) side
plate screws and the intramedullary nail where failure might occur
after union. This study compares different implant configurations
in order to investigate bridging the gap between the distal DHS
and tip of the intramedullary nail. Methods. A total of 29 left synthetic femora were tested in three groups:
1) gapped short nail (GSN); 2) unicortical short nail (USN), differing
from GSN by the use of two unicortical bridging screws; and 3) bicortical
long nail (BLN), with two angled bicortical and one unicortical bridging
screws. With these findings, five matched-pairs of cadaveric femora
were tested in two groups: 1) unicortical long nail (ULN), with
a longer nail than USN and three bridging unicortical screws; and
2) BLN. Specimens were axially loaded to 22.7 kg (50 lb), and internally
rotated 90°/sec until failure. Results. For synthetic femora, a difference was detected between GSN and
BLN in energy to failure (p = 0.04) and
A total of 80 patients with an acute rupture of tendo Achillis were randomised to operative repair using an open technique (39 patients) or non-operative treatment in a cast (41 patients). Patients were followed up for one year. Outcome measures included clinical complications, range of movement of the ankle, the Short Musculoskeletal Function Assessment (SMFA), and muscle function dynamometry evaluating dorsiflexion and plantar flexion of the ankle. The primary outcome measure was muscle dynamometry. Re-rupture occurred in two of 37 patients (5%) in the operative group and four of 39 (10%) in the non-operative group, which was not statistically significant (p = 0.68). There was a slightly greater range of plantar flexion and dorsiflexion of the ankle in the operative group at three months which was not statistically significant, but at four and six months the range of dorsiflexion was better in the non-operative group, although this did not reach statistically significance either. After 12 weeks the peak
Aims. Varus-valgus constrained (VVC) implants are often used during revision total knee arthroplasty (TKA) to gain coronal plane stability. However, the increased mechanical
Objectives. The most prevalent disorders of the shoulder are related to the
muscles of rotator cuff. In order to develop a mechanical method
for the evaluation of the rotator cuff muscles, we created a database
of isometric force generation by the rotator cuff muscles in normal
adult population. We hypothesised the existence of variations according
to age, gender and dominancy of limb. Methods. A total of 400 healthy adult volunteers were tested, classified
into groups of 50 men and women for each decade of life. Maximal
isometric force was measured at standardised positions for supraspinatus,
infraspinatus and subscapularis muscles in both shoulders in every
person.
We hypothesised that a minimally invasive peroneus
brevis tendon transfer would be effective for the management of
a chronic rupture of the Achilles tendon. In 17 patients (three
women, 14 men) who underwent minimally invasive transfer and tenodesis
of the peroneus brevis to the calcaneum, at a mean follow-up of
4.6 years (2 to 7) the modified Achilles tendon total rupture score
(ATRS) was recorded and the maximum circumference of the calf of
the operated and contralateral limbs was measured. The strength
of isometric plantar flexion of the gastrocsoleus complex and of
eversion of the ankle were measured bilaterally. Functional outcomes
were classified according to the four-point Boyden scale. . At the latest review, the mean maximum circumference of the calf
of the operated limb was not significantly different from the pre-operative
mean value, (41.4 cm, 32 to 50 vs 40.6 cm, 33 to
46; p = 0.45), and not significantly less than that of the contralateral
limb (43.1 cm, 35 to 52; p = 0.16). The mean peak
As has been shown in larger animal models, knee immobilization can lead to arthrofibrotic phenotypes. Our study included 168 C57BL/6J female mice, with 24 serving as controls, and 144 undergoing a knee procedure to induce a contracture without osteoarthritis (OA). Experimental knees were immobilized for either four weeks (72 mice) or eight weeks (72 mice), followed by a remobilization period of zero weeks (24 mice), two weeks (24 mice), or four weeks (24 mice) after suture removal. Half of the experimental knees also received an intra-articular injury. Biomechanical data were collected to measure passive extension angle (PEA). Histological data measuring area and thickness of posterior and anterior knee capsules were collected from knee sections.Aims
Methods
We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion
The aim of this retrospective study was to assess the incidence of early periprosthetic femoral fracture (PFF) associated with Charnley-Kerboull (CK) femoral components cemented according to the ‘French paradox’ principles through the Hueter anterior approach (HAA) in patients older than 70 years. From a prospectively collected database, all short CK femoral components implanted consecutively from January 2018 to May 2022 through the HAA in patients older than 70 years were included. Exclusion criteria were age below 70 years, use of cementless femoral component, and approaches other than the HAA. A total of 416 short CK prostheses used by 25 surgeons with various levels of experience were included. All patients had a minimum of one-year follow-up, with a mean of 2.6 years (SD 1.1). The mean age was 77.4 years (70 to 95) and the mean BMI was 25.3 kg/m2 (18.4 to 43). Femoral anatomy was classified according to Dorr. The measured parameters included canal flare index, morphological cortical index, canal-calcar ratio, ilium-ischial ratio, and anterior superior iliac spine to greater trochanter (GT) distance.Aims
Methods
Objectives. Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL). Materials and Methods. A total of 54 osteoporotic human cadaver thoracic and lumbar vertebrae were instrumented with pedicle screws (uncemented, solid cemented or fenestrated cemented) and augmented with high-viscosity PMMA cement (0 mL, 1 mL or 3 mL). The insertion
In 11 paediatric patients (seven girls and four
boys, from 12 to 15 years old) with unilateral obligatory patellar dislocation
and ligamentous laxity vastus medialis advancement, lateral release,
partial patellar ligament transposition and Galeazzi semitendinosus
tenodesis was undertaken to stabilise the patella. The diagnostic criterion
for ligamentous laxity was based on the Beighton scale. Outcomes
were evaluated radiologically and functionally by measurement of
the range of knee movement and isokinetic testing. The evaluation
also included the Lysholm knee scale. Follow-up studies took place
at a mean of 8.1 years (5 to 15) post-operatively. Normal patellar tracking without any recurrence of dislocation
was obtained in ten out of 11 patients. Pain related to vigorous
activity was reported by nine patients. Compared with the opposite
normal side, the isokinetic tests revealed a statistically significant
decrease in the maximal
Although absorbable sutures for the repair of acute Achilles tendon rupture (ATR) have been attracting attention, the rationale for their use remains insufficient. This study prospectively compared the outcomes of absorbable and nonabsorbable sutures for the repair of acute ATR. A total of 40 patients were randomly assigned to either braided absorbable polyglactin suture or braided nonabsorbable polyethylene terephthalate suture groups. ATR was then repaired using the Krackow suture method. At three and six months after surgery, the isokinetic muscle strength of ankle plantar flexion was measured using a computer-based Cybex dynamometer. At six and 12 months after surgery, patient-reported outcomes were measured using the Achilles tendon Total Rupture Score (ATRS), visual analogue scale for pain (VAS pain), and EuroQoL five-dimension health questionnaire (EQ-5D).Aims
Methods
The February 2024 Spine Roundup360 looks at: Surgeon assessment of bone – any good?; Robotics reduces radiation exposure in some spinal surgery; Interbody fusion cage versus anterior lumbar interbody fusion with posterior instrumentation; Is robotic-assisted pedicle screw placement an answer to the learning curve?; Acute non-traumatic spinal subarachnoid haematomas: a report of five cases and a systematic review of the literature; Is L4-L5 lateral interbody fusion safe and effective?
We have compared the time to recovery of isokinetic
quadriceps strength after total knee replacement (TKR) using three
different lengths of incision in the quadriceps. We prospectively
randomised 60 patients into one of the three groups according to
the length of incision in the quadriceps above the upper border
of the patella (2 cm, 4 cm or 6 cm). The strength of the knees was
measured pre-operatively and every month post-operatively until
the peak quadriceps
Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model. We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition.Aims
Methods
A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions.Aims
Methods