Surgical management of renal cancer metastasis in the humerus: novel use of a trabecular metal spacer.

Humeral metastases from renal cell carcinoma are not uncommon. Current surgical practice centres around adequate tumour resection, but often at the expense of functional outcome. The use of trabecular metal (TM) implants is well described in spine and joint surgery. However, their use as a reconstruction device in osseous tumour surgery has yet to be reported. We present our experience in using a TM vertebral body replacement device (VBR) in treating a patient with painful bilateral diaphyseal humeral metastases. Resection of the tumour resulted in defects which the TM-VBR was able to fill. The defect was then bridged with a locking plate and cables. At 2-year clinical and radiographic review, bony integration and a return to pain free, near-normal function was achieved.

The posterior acetabular wall (PAW): an aid to acetabular orientation at primary THA.

INTRODUCTION: Incorrect acetabular component positioning during total hip arthroplasty (THA) may lead to dislocation, impingement, wear and revision. Surgeons commonly use the transverse acetabular ligament (TAL) as a landmark for acetabular component orientation. The posterior acetabular wall (PAW) is a structure easily viewed on plain radiography and its position can help guide acetabular component position. In this study, we examine the efficacy of preoperative radiographs in predicting cup position relative to the PAW. METHODS: Prospective data was recorded on radiographic findings of the posterior wall (prominent, normal, deficient) on a consecutive series of 200 primary THAs utilising a standardised posterior approach. The final cup position relative to the wall was recorded (prominent, flush, deep). Cup inclination and version were then assessed by postoperative radiography and any instances of dislocation recorded. RESULTS: There were 117 females and 83 males with a mean age of 66.5 years. 154 were recorded as having a normal PAW on radiographs, 152 had the cup positioned in line with the TAL and flush to the PAW. 29 had a deficient PAW and 27 of these had a cup positioned prominently with 17 having a prominent PAW and of these 16 a deep cup position. Postoperative radiographs showed a mean cup version of 20.8° and inclination of 44.7° using this method. There were 21 outliers (10.5%) with no dislocations at a minimum 12-month follow-up. CONCLUSIONS: The TAL is a continuation of the posterior labrum. As such, the posterior wall is a useful adjunct to and surrogate landmark for the TAL. It has the added advantage that it is visible on radiographs and so aids surgical planning with respect to cup positioning.

Hip stability after ligamentum teres resection during surgical dislocation for cam impingement.

PURPOSE: The purpose of this study was to investigate whether patients who have undergone surgical hip dislocation with excision of the ligamentum teres exhibited symptoms of a Type I ligamentum teres rupture. METHOD: A questionnaire was designed to enquire about specific symptoms attributed to Type I injuries (complete rupture) in the literature: gross instability, incomplete reduction, inability to bear weight and mechanical symptoms. 217 consecutive patients were surveyed and 161 patients (75%) returned 168 questionnaires (75%). Mean age was 34 and median follow-up was 51 months (35 to 97). RESULTS: All patients were able to fully weight bear after surgery while 77% experienced no groin pain and 61% experienced no pain on exercise. 35% of patients experienced popping and locking in their operated hip and 24% had subjective feeling of their hip giving way. CONCLUSION: Patients who have had surgical excision of the ligamentum teres during open osteochondroplasty for cam deformities do not exhibit symptoms of a Type I ligamentum teres rupture. Our results show that minor instability symptoms may be present but symptoms present more like to Type II (partial) injuries. We propose that Type II injuries be divided into Type IIa; partial tear and Type IIb; iatrogenic rupture.

Hang them high: a hands-free technique for limb-holding during surgical preparation.

We describe the use of a suspension system to provide hands-free elevation and traction of lower limbs during preoperative skin preparation. The technique is particularly useful for fractured limbs that are often both awkward to elevate by hand and present a physical challenge to lift and hold. Furthermore, limb-lifting and holding has been identified by the National Association of Orthopaedic Nurses as a commonly performed task associated with high risk of work-related musculoskeletal disorders. The National Association of Orthopaedic Nurses Task Force has recommended the use of assisted lifting and holding devices if the task of limb elevation and or holding exceeds its recommended limits. The principal determinants of these limits are the weight of the leg, the height it is elevated above the chest, and the time for which it is held. The maximal weight recommended for a two hand lift is 35 pounds, which is often less than the weight of a patient's leg whose total body weight is over 190 pounds. The maximal limit is below 35 pounds for lifts above chest height and for holds over 1 minute. Because the average size and weight of American citizens is increasing, so has the need for devices to assist with lifting and holding in the operating room. This technique also can improve operating room efficiency because a member of the operating team is not engaged in holding the limb during the skin preparation and draping. The limb is also held reliably with constant in-line traction by this technique. This reduces the chance for accidental decontamination of the skin or further movement of the fracture and potential secondary soft tissue damage if the limb holder loses or changes their grip.

In vitro influence of stem surface finish and mantle conformity on pressure generation in cemented hip arthroplasty.

BACKGROUND AND PURPOSE: Under physiological loads, debonded cemented femoral stems have been shown to move within their cement mantle and generate a fluid pump that may facilitate peri-prosthetic osteolysis by pressurizing fluid and circulating wear debris. The long-term physiological loading of rough and polished tapered stems in vitro has shown differences in performance, with greater interface pressures generated by the rough stems. In this study we investigated the individual effects of stem surface finish, degree of mantle wear, and mode of loading on the stem pump mechanism. METHOD: Rough and polished stems were loaded under different regimes in artificially worn cement mantles that permitted either 2 or 5 degrees of rotational stem movement, and the interface pressures were compared. RESULTS: The pressures generated by the rough and polished stems were similar in either type of mantle. The pattern of pressure generation in the 2-degree mantles was similar to the pressures generated by rough stems after long-term loading, but the high posterior wall pressures fell and the tip pressures increased in the 5-degree mantles. The torsional loads were principal drivers of pressure generation in all areas of the interface other than the implant tip, where axial loading predominated. INTERPRETATION: Femoral stems with rotational instability under cyclic torsional loads generate elevated interface fluid pressures and flows independently of stem surface finish. The rough surface finish is only important in creating this instability in tapered stems.

In vitro comparison of the effects of rough and polished stem surface finish on pressure generation in cemented hip arthroplasty.

BACKGROUND AND PURPOSE: High pressures around implants can cause bone lysis and loosening. We investigated how pressures are generated around cemented femoral stems. METHOD: We compared the pressures generated by rough and polished tapered stems at their cement interfaces, in an in vitro model, before and after 1 million load cycles. RESULTS: At the start of the study, the loading of both polished and rough stems generated interface pressures that were not statistically significantly different. After 1 million load cycles, the rough stems generated greater interface pressures than at the start (p = 0.03), with maximum pressure wave amplitudes of 450,000 Pa or 3,375 mm Hg. The pressures generated by polished stems were similar before and after 1 million load cycles, and were lower than the pressures generated by the rough stems (p = 0.01). Stem loading caused micromotion between the stem and cement. Polished stems migrated distally in the cement but retained rotational and axial stability. The rough stems also migrated distally and wore the cement mantle, leading to increased rotational instability. INTERPRETATION: The change in the rotational micromotion of the rough stem is likely to be the principal cause of the increased stem pump output and to be a key factor in the longevity of cemented femoral implants.

The use of traction to simplify intramedullary fixation of paediatric forearm fractures.

A minority of paediatric and early adolescent diaphyseal forearm fractures require operative fixation. The method of closed reduction and intramedullary stabilisation of such fractures using stainless steel pins or flexible titanium nails has well documented success rates. The literature proposing their use advises the wires are inserted with the forearm resting free on a radiolucent arm table. In our experience, this technique is demanding; the fracture sites are unstable, often with soft tissue interposition, and the proximal radial fragment is difficult to control by closed means because of the overlying muscle mass. The technique, we describe, employs a standard Maquet Orthostar traction table (Maquet, Colima Ave, Hylton Riverside, Sunderland, UK) to effect a stable closed reduction of diaphyseal forearm fractures to simplify the procedure of passing the radial wire. The traction is then released to allow elbow flexion and the ulna wire to be passed, the ulna fracture having been reduced by the traction and stabilised by the radial wire. In summary, the use of traction to reduce and stabilise the radial fracture has simplified the surgery and reduced operative time.