Cantilever Failure of Modular Uncemented Femoral Revision Stem in Patients with Poor Proximal Femoral Support; How to avoid it?

Objectives: Revision hip arthroplasty is a major surgical challenge and is even more difficult in cases with a deficient proximal femur. Modular uncemented cone body revision femoral stems were introduced as a solution. They have the advantage of optimising joint kinematics by allowing the variable degrees of version, offset and leg length. However, we noticed cantilever failure of such stems, particularly in patients with deficient proximal femoral support. Fatigue fracture of the revision femoral stems should raise questions about its use in patients with insufficient proximal femoral bone support. Methods: We present a case series of five patients with the cantilever failure of Stryker restoration modular stem conical distal femur prosthesis. These cases were identified during a retrospective review of revision hip surgeries performed at our trust. Results: The stem failed after an average of 22.6 months post-revision surgery. Primarily, poor proximal femur bone support with a well-fixed distal stem and secondarily high BMI led to this catastrophic failure in the absence of trauma. All five cases were re-revised to Stanmore proximal femoral replacement and achieved good functional outcomes after an average follow-up of seven years. Conclusion: Proximal femoral bone support should be restored to prevent early cantilever failure of distally fixed proximal modular revision femoral stems. Consider a proximal femoral replacement if we cannot ensure proximal bone support.

Validity of direct magnetic resonance arthrogram in patients with femoroacetabular impingement and their outcome post hip arthroscopy.

Femoroacetabular Impingement is an established cause of labral tears and chondral delamination. The aim was to test the validity of direct magnetic resonance arthrogram [dMRA] in the diagnosis of the same. We also looked at the short term functional outcome in these patients post hip arthroscopy. The dMRA is valuable in diagnosing labral tears nevertheless poor in detecting cartilage delamination. Hip arthroscopic intervention provided a good short-term functional outcome; however, should be offered with caution in patients over 40 years. To our knowledge, this is the single largest series published with similar methodology.

Comparison of the reconstruction trochanteric antigrade nail (TAN) with the proximal femoral nail antirotation (PFNA) in the management of reverse oblique intertrochanteric hip fractures.

Reverse oblique intertrochanteric fractures have unique mechanical characteristics and are often treated with intramedullary implants. We compared the outcomes of the reconstruction trochanteric antegrade nail (TAN) with the proximal femoral nail antirotation (PFNA). Between July 2008 and February 2014, we reviewed all patients with reverse oblique intertrochanteric fractures treated at our hospital. Patients with pathological fractures and those who were treated with other than TAN and PFNA nailing systems were excluded. Preoperative assessment included the Abbreviated mental test score (AMT), the ASA grade, pre-injury mobility and place of residence. Postoperative outcome measures included the type of implant used, time to fracture union, failures of fixation and revision surgeries. Fifty-eight patients were included and divided into two groups based on the treatment: 22 patients treated with TAN and 36 patients treated with PFNA systems. The two groups were well matched with regards to demographics and fracture type. The overall union rate was similar in both groups but the time to union was shorter in the TAN group. There were 8 implant failures in the PFNA (22.2%) group compare to none in the TAN group. Implant failure was associated with the severity of fracture (AO 31.A3.3) but was not related to fracture malreduction or screw position (Tip-apex-distance). Our study suggests that the use of reconstruction system with two screws such as TAN may be more suitable implant for reverse oblique intertrochanteric hip fractures.

The anatomy and function of the obturator externus.

There is limited knowledge regarding the anatomic relationships and functional anatomy of the Obturator Externus muscle (OE). It is described as a muscle which originates from the external bony margin of the obturator foramen with a cylindrical tendon which passes like a sling under the femoral neck and inserts in the trochanteric fossa. The primary aim of this study is to describe the OE morphology and its anatomic relationship to the acetabulum. A secondary aim is to postulate its action. Eighteen fresh human cadaveric hips were dissected to investigate the anatomy of the OE. A plastic model of the pelvis and femur was used to create a string model based on a technique previously described by Beck et al. The plastic model was used to determine the function of the OE.We conclude that the Obturator externus muscle helps to stabilise the head of the femur in the socket. The mechanical model demonstrated that the primary action of the obturator externus muscle was to externally rotate the femur when the hip was in neutral position and flexed at 90°. Its secondary function was as an adductor when the hip was in flexion.

A safe overhang limit for unicompartmental knee arthroplasties based on medial collateral ligament strains: an in vitro study.

Excessive tibial component overhang during unicompartmental knee arthroplasty (UKA) may cause medial collateral ligament (MCL) impingement, which, in turn, may lead to medial knee pain [Chau et al. Tibial component overhang 226 following unicompartmental knee replacement-does it matter? The Knee. 2009;16(5):310-3]. This study examines MCL loads in 6 human cadaveric knees for different levels of overhang using a robotic testing system. The results indicated no statistically significant difference between the baseline MCL load (no overhang) and the 2-mm overhang (P = .261). However, there were significant differences in MCL load between 2- vs 4-mm (P = .012) and 2- vs 6-mm overhang (P = .022). The loads were almost doubled from 2 to 4 mm of overhang. We conclude that, to minimize pain from excessive MCL loading, surgeons should avoid tibial component overhang greater than 2 mm in unicompartmental knee arthroplasties.

Aseptic loosening of total hip replacement presenting as an anterior thigh mass.

Aseptic loosening is one of the commonest complications of total hip replacement that can cause pain and instability. The chronic inflammatory response to the wear debris from the polyethylene or metal can cause osteolysis and implant failure. We report a case of aseptic loosening of the hip, presented with a swelling over the anterior thigh without any pain or instability in the joint. This mass was a foreign body granuloma formed secondary to the polyethylene wear debris due to the instability of the polyethylene in the metal shell. The patient underwent successful revision hip arthroplasty after the removal of the foreign body granuloma.

Bilateral femoral insufficiency fractures likely related to long-term alendronate therapy.

Osteoporosis-related fractures are a major public health problem and one in two women and one in four men are affected with osteoporosis-related fractures. Alendronate (Fosamax) is one of the first bisphosphonates used to treat osteoporosis effectively. Recently, however, there is a concern regarding long bone insufficiency fractures related to long-term alendronate therapy. We report a case of bilateral femoral insufficiency fractures likely related to long-term alendronate therapy, the classic symptoms, signs, and treatment of these fractures.

Stress fracture of the fourth metatarsal in a child: a case report and review of the literature.

Metatarsal stress fractures are uncommon in the children. They usually occur in the distal part of the metatarsal and common in second and third metatarsals. Stress fracture in the proximal fourth metatarsal in a child is very rare. We report a stress fracture in the proximal fourth metatarsal in an 8-year-old boy, which was successfully treated with non-operative management.

Primary septic arthritis of the acromio-clavicular joint: case report and review of literature.

Primary septic arthritis of the Acromio clavicular joint is an uncommon disorder and is rarely seen even in an immunocompromised individual. We report a case of primary septic arthritis of the acromio-clavicular (A-C) joint caused by Staphylococcus aureus without any predisposing factors. The patient was admitted with left shoulder pain, restricted movements and fever. Laboratory parameters showed high C-reactive protein, raised erythrocyte sedimentation rate and leucocytosis. Blood cultures were positive for Staphylococcus-aureus. Magnetic resonance imaging (MRI) using Gadolinium enhancement revealed marked effusion in the A-C joint. Aspiration from the A-C joint revealed a heavy growth of Staphylococcus-aureus. The patient was successfully treated with 8 weeks of appropriate antibiotics with complete resolution of infection and return to full function.