The functional outcome with metallic radial head implants in the treatment of unstable elbow fractures: a long-term review.

BACKGROUND: A long-term review of metal prosthetic radial head replacement in patients with radial head fractures associated with gross instability of the elbow has been performed. METHOD: Twenty patients were reviewed using a modified Mayo Clinic functional rating index system. The mean follow-up was 12.1 years, with a range from 6 to 29 years. RESULTS: Results were excellent in 12 patients, good in 4 patients, fair in 2 patients, and poor in 2 patients. A metal radial head replacement restored elbow stability when fracture of the radial head occurred in combination with dislocation of the elbow, rupture of the medial collateral ligament, fracture of the proximal ulna, and/or fracture of the coronoid process. CONCLUSION: We conclude that a metal radial head prosthesis has select indications. We advocate its use when the radial head cannot be reconstructed in the setting of a clinically unstable elbow. Results suggest that it functions well on a long-term basis.

Biomechanical analysis of the Medoff sliding plate.

BACKGROUND: A new device for fixation of hip fractures the Medoff plate was biomechanically tested and compared with the Ambi plate and Gamma nail. METHODS: Six pairs of human cadaveric femurs were used. The characteristics evaluated were structural stiffness, strain distribution, and modes of failure. Results were compared with the Ambi plate and Gamma nail biomechanical studies from a previous study that used the same methods. RESULTS: The Medoff plate was stiffer than the other two implants for intertrochanteric fractures, and for segmental subtrochanteric fracture. The Medoff plate was more load sharing than the other implants in these fracture configurations. The mean load to failure was lower than for the Ambi plate or the Gamma nail. CONCLUSION: The Medoff plate is a better load-sharing device than the Ambi (DHS) or Gamma nail systems. The main concern is its structural weakness. The implant failed at loads 50% less than other devices. The greatest risk of implant failure is with unstable subtrochanteric fractures.

Fracture of the patella following total knee arthroplasty.

The charts of 21 patients (22 knees) with significant radiographic changes of the patella after total knee arthroplasty were reviewed. The average patient age was 73 years, and average follow-up after arthroplasty was 7.3 years. Lateral release, fat pad excision, quadriceps tendon release, and previous surgery were implicated in the etiology of fracture of the patella. Five cases had type 1 pattern (sclerosis, fragmentation, and no fracture), 5 cases had type 2 pattern (undisplaced fracture and fragmentation), and 12 cases had type 3 pattern (displaced fracture and fragmentation). Type 1 and 2 patterns required no surgical treatment and were rated good to excellent according to the Hospital for Special Surgery Disability Score Sheet. Patients with a type 3 pattern who did not undergo surgery were rated poor to fair, while patients with a type 3 pattern who underwent surgical treatment (patellectomy, removal of the patellar component, or excision arthroplasty for infection) were rated good. Patellectomy is the treatment of choice for patients with displaced fractures of the patella. A classification system for the pattern of patellar changes is proposed.

Micromotion secondary to axial, torsional, and shear loads in two models of cementless tibial components.

Tibial component loosening and lack of bone ingrowth remain serious problems in uncemented knee arthroplasty. Initial implant stability is the most important factor in achieving bone ingrowth. Eccentric axial loading causing liftoff has been identified as a potential problem, but the role of torsion and shear stability is unclear. This study assesses the micromotion in two uncemented components subjected to eccentric axial (lateral, medial, posterior, anterior), shear, and torsional loads. Four configurations were tested: Tricon M (pegs) (Smith and Nephew Richards, Memphis, TN), Genesis (stem only) (Smith and Nephew Richards), Genesis with screws, and Genesis with pegs. Nine pairs of cadaver tibias were implanted, and cyclic loads were applied. Micromotion was measured with two linear variable differential transformers. Micromotion values for each mode of loading were compared using a one-way analysis of variance. Genesis with screws had the least micromotion for all applied loads (14-33 micrometers), whereas Genesis with stem only has the maximum value of micromotion (27-212 micrometers). Genesis wit and Tricon had intermediate ranges of micromotion (32-121 and 107-140 micrometers, respectively). It is concluded that peg fixation and stem fixation are inadequate and result in significant micromotion. Stem plus screws provides the most stable fixation and may be compatible with bone ingrowth.

Hydroxyapatite coating on carbon composite hip implants in dogs.

In 33 dogs we implanted femoral stems made either of carbon composite, some coated with hydroxyapatite, or of titanium alloy with a porous coating. Osseointegration was greater in the hydroxyapatite-coated than in the un-coated stems (p less than 0.001). Push-out tests, at an average of 7.2 months after implantation, showed a six-fold increase in interface shear strength and a twelve-fold increase in shear stiffness in the hydroxyapatite-coated group compared with noncoated implants. The highest shear-strength values were found in the porous-coated titanium alloy stems, around which there was also the most resorptive bone remodelling.

The natural history of suspected scaphoid fractures.

Clinically suspected scaphoid fractures are common injuries. The authors prospectively followed up, by serial radiography and bone scanning, 23 patients who had a history of trauma to the carpus and associated localized tenderness to the anatomic "snuff box": in 15 patients the radiographs and bone scans were negative; in 5 the radiograph was equivocal and the bone scan positive. The authors concluded that patients with clinically suspected scaphoid fractures and negative radiographs can be treated symptomatically without immobilization in a cast. Patients with equivocal radiographs should be assumed to have a fractured scaphoid and treated accordingly.

A plaster-pylon technique for below-knee amputation.

We reviewed 83 patients after below-knee amputation. In 56 with 69 amputations early management was by plaster-pylon. A plaster cast is applied in the operating room, and a pylon added one week later, after which full weight-bearing is allowed. We compared these patients with 27 who had soft bandaging. The 'healing' time was reduced from 98 days to 40 days, and there were no major complications in the plaster-pylon group. The technique is simple and cheap and can be used by paramedical staff without specialised training or equipment.

The stability of intertrochanteric fractures treated with a sliding screw-plate.

Failure of fixation is a major complication of the treatment of unstable intertrochanteric fractures. A retrospective review was performed of 54 such fractures treated with a sliding screw-plate device. Linear and angular displacements were calculated from radiographs taken at operation and serially until healing was complete. Linear displacement was related to fracture instability, but the neck-shaft angle was relatively constant during healing. Complications were often due to failure of the sliding mechanism of the implant. We conclude that a sliding screw-plate allows controlled collapse of the major fragments but maintains the neck-shaft angle even in unstable fractures.

Lower extremity amputations: a 5-year review and comparative study.

In order to review major lower extremity amputations at the Toronto East General and Orthopaedic Hospital Inc. between 1979 and 1984, 60 patients with 42 below-knee, 17 mid-thigh and 20 Callander through-knee amputations were studied retrospectively. The three amputation groups demonstrated comparable rates of stump healing. A previous history of vascular surgery on the extremity increased the risk for both delayed healing and failure to heal. The Callander through-knee amputees were rehabilitated earlier and more easily than were the mid-thigh amputees, and once rehabilitated they were more likely to continue using their prostheses. The authors recommend that, when possible, the chosen site of amputation for the majority of patients should be below the knee, but when this is not practical a through-knee amputation should be done in preference to a mid-thigh amputation.

Delayed union and nonunion of the tibia: experience in a community teaching hospital.

Delayed union and nonunion are frequent sequelae of high-energy tibial fractures, particularly compound ones. The authors studied 45 such cases; of these, 20 fractures were compound. The authors analysed the initial management but found no apparent correlation between the initial management of these fractures and subsequent delayed union or nonunion. The Phemister bone-grafting technique was used to achieve union and was considered a safe, efficacious method. Aggressive initial management of the soft-tissue component of tibial fractures is recommended to minimize the possible development of chronic osteomyelitis, a serious complication that occurred in eight patients and necessitated below-knee amputation in three.

Treatment of unstable fractures of the distal radius by external fixation.

The Roger Anderson external fixator was used in the treatment of unstable fractures of the distal radius in 52 patients, and the results evaluated after a follow-up averaging 58 months. The indications for its use were failure to maintain adequate closed reduction using plaster, and instability of the fracture as determined by the initial radiographs. Our radiological criteria for instability included dorsal angulation of more than 20 degrees, fractures involving the joint, radial shortening of more than 10 mm, and severe dorsal comminution. Using the Lucas modification of the Sarmiento demerit point-rating system, we found that 46 patients (89%) had good or excellent results and six (11%) were classified as fair. There were no poor results. Seven patients (14%) developed complications. None of these affected the long-term results except in one elderly woman where the pins loosened and had to be removed.

Use of a pylon for early ambulation after below-knee amputation: a preliminary report.

The fitting of a prosthesis immediately after amputation offers many advantages. These include early ambulation, more rapid healing of the amputation site and a decrease in the number of complications resulting from prolonged bed rest. The major problems preventing the widespread use of immediate fitting are the specialized prosthetic care required and the high cost of the appliance. The authors describe a new pylon designed for early ambulation after below-knee amputation. Its application does not require special training, it is inexpensive, safe and effective. This pylon was used in the early postoperative period in 20 amputees, without any major complications.

Replacement of the radial head in the treatment of unstable elbow fractures.

The use of a radial head prosthesis for the treatment of fractures of the radial head associated with gross instability of the elbow is described. Seventeen fractures occurring in seventeen patients treated at the Toronto East General Hospital from 1966 to 1979 are analysed. Instability of the elbow occurs when fracture of the radial head is combined with dislocation of the elbow, fracture of the proximal ulna, fracture of a major portion of the coronoid process and rupture of the medial ligament. Stability can be restored in these injuries by inserting a radial head prosthesis which acts as a joint spacer. A metallic prosthesis which acts as a joint spacer. A metallic prosthesis was used in 15 patients and a silastic cap in 2. The results of this method of treatment for a difficult problem age good. We are not advocating the routine use of a prosthesis for simple fractures of the radial head. It is indicated for injuries where stability is poor after excision of the radial head. There is little information in the literature regarding the use of a prosthesis for radial head fractures.

A bioengineering analysis of force actions at the knee in normal and pathological gait.

The paper describes a simplified bioengineering analysis for the determination of force actions at the knee joint for normal and pathological gaits. The stance phase of the gait cycle only is considered, and gravitational and inertia forces are excluded from the analysis. The anatomical and functional assumptions required for analysis are discussed. Force actions transmitted at the knee joint by the bearing surfaces, muscles and ligaments for normal individuals are presented with reference to magnitude and phasic relationship for the activity of level walking. Bearing loads transmitted at the knee joints of pathological limbs are also discussed.

Treatment of infected un-united femoral shaft fractures.

Twenty patients treated for osteomyelitis following intramedullary fixation of fractures of the femoral shaft were assessed from the standpoint of antibiotics, internal fixation, drainage, sequestrectomy and external support. Analysis of intramedullary fixation in the form of Küntscher nailing with respect to the rate of union, duration of treatment and number of operative procedures, suggests that rigid intramedullary fixation is superior to plates and screws and plays an important role in development of union in the presence of infection.