Distal radioulnar joint: functional anatomy, including pathomechanics.

The distal radioulnar joint allows the human to rotate the forearm to place the hand in a desired position to perform different tasks, without interfering with the grasping function of the hand. The ulna is the stable part of the forearm around which the radius rotates; the stability of the distal radioulnar joint is provided by the interaction between ligaments, muscles and bones. The stabilizing structures are the triangular fibrocartilage complex, the ulnocarpal ligament complex, the extensor carpi ulnaris tendon and tendon sheath, the pronator quadratus, the interosseous membrane and ligament, the bone itself and the joint capsule. The purpose of this review article is to present and illustrate the current understanding of the functional anatomy and pathomechanics of this joint.

Biomechanical comparison of the hand-based transplant used in bone-tissue-bone scapho-lunate ligament reconstruction.

Although work has been published comparing the five most commonly used transplant techniques to the properties of the scapho-lunate interosseous ligament (SLIL), no study has been carried out which compares the biomechanical properties of the different bone-tissue-bone autografts to each other, using a standard methodology of testing. The hypothesis of this study was that mechanically significant differences in the material properties of commonly used bone-tissue-bone exist when compared to each other. We tested the dorsal part of the SLIL and the five most quoted transplants in the literature: capitate to trapezoid; trapezoid to second metacarpal; third metacarpal-carpal; dorsal capitate-hamate; 4-5 extensor retinaculum. For each transplant, we measured failure load, failure displacement, width, and thickness. Anova was used to compare the different results obtained and the level of significance attributed to P<0.05. Load to failure were: SLIL 94.3±42.86N; capitate to trapezoid 37.7±23.13N; trapezoid to second metacarpal 45.43±14.28N; third metacarpal-carpal 60.11±19.94N; dorsal capitate-hamate 63±25.51N; 4-5 retinaculum 15.67±10.7N. Only the dorsal capitate-hamate ligament showed to have no significant (P>0.05) difference in term of load to failure, all the others was significantly weaker (P<0.05). Previous biomechanical studies have identified the dorsal region of the SLIL as the most structurally and functionally important area of the SLIL. As a result, attention has been more specifically brought to the replacement of the dorsal portion of the SLIL. An attempt to achieve a reconstruction that reproduces more closely the SLIL has generated research on the use of bone-tissue-bone composite graft, several donor sites have been used in order to find the most similar. Our results suggest that, using a normalized method to compare the previously described grafts harvested at the wrist level, that the dorsal capitate-hamate ligament has the closest properties to the native dorsal scapho-lunate ligament.

The effect of radioscapholunate fusion on wrist movement and the subsequent effects of distal scaphoidectomy and triquetrectomy.

Radioscapholunate arthrodesis is a salvage procedure indicated for osteoarthritis of the radiocarpal joint involving the lunate facet of the radius. This cadaver study examines changes in wrist motion resulting from radioscapholunate arthrodesis, and the effects of surgical techniques to improve the range of motion. Simulated radioscapholunate arthrodesis, distal scaphoidectomy and triquetrectomy were carried out sequentially on six cadaver forearms and measurements (maximum flexion/extension and radial/ulnar deviation) were taken in the intact situation and after each surgical step using a magnetic tracking device. Radioscapholunate arthrodesis diminishes the amplitudes of movements of the wrist in all directions, but range of motion in the radioscapholunate fused wrist improves after scaphoidectomy and improves further after triquetrectomy (88% of original flexion/extension and 98% of original radial/ulnar deviation). Radioscapholunate arthrodesis causes a significant change in kinematics between the hamate and the triquetrum in flexion/extension.

[Radioulnar impingement after distal ulnar resection and ulnar head hemiresection interposition arthroplasty (Bowers procedure). An experimental biomechanical study]. / Radioulnares Impingement nach Resektion der distalen Ulna und Ulnakopfhemiresektions-Interpositionsarthroplastik nach Bowers - Eine experimentelle biomechanische Studie.

Resection of the distal ulna (Darrach operation) and the ulnar head hemiresection interposition arthroplasty (Bowers procedure) are common methods of treating the arthrotic distal radioulnar joint (DRUJ). The purpose of this study was to evaluate the dynamic effects of both the Bowers operation and the resection of the distal ulna on radioulnar impingement and dorsal-palmar displacement and to compare their biomechanical performances. With a dynamic forearm simulator forearm rotation was performed with simultaneous loading of relevant muscles. Torque along the forearm axis was generated by simulated muscle action with loading of the relevant tendons while the wrist was constrained to prescribed ranges of motion. The instability of the radius relative to the ulna was evaluated using displacement data of digitized landmarks in an ulnar coordinate system. Seven fresh-frozen cadaver upper extremities were used. Resection of the distal ulna created a significant instability of the forearm with movement of the radius ulnarly. Anteroposterior translations in each loading condition could be detected as well but the magnitude of displacement was little and less predictable. The results of the Bowers operation demonstrated significantly less instability compared with the Darrach results. Our data demonstrates that the dynamic behavior of the Bowers procedure is superior to the mechanical performance of complete resection of the distal ulna.

[Dynamic radioulnar convergence after Darrach operation, soft tissue stabilizing operations of the distal ulna and ulnar head prosthesis implantation--an experimental biomechanical study]. / Dynamische radioulnare Konvergenz nach Darrach-Operation, Weichteilstabilisierungsoperationen der distalen Ulna und Ulnakopfprothesenimplantation--Eine experimentelle biomechanische Studie.

The most common method of treating the arthrotic distal radioulnar joint (DRUJ) is resection of the entire ulnar head (Darrach procedure). Complications related to instability of the distal forearm resulting from loss of the ulnar head are usually manifested by pain and weak grip strength and have remained the drawbacks of this procedure. In an attempt to mechanically stabilize the distal forearm, an endoprosthesis was developed to replace the ulnar head after Darrach resection. The purpose of this study was to: 1) evaluate the dynamic effects of the Darrach procedure on radioulnar convergence; and 2) evaluate the mechanical efficacy of two soft tissue stabilizing techniques (Pronator quadratus advancement flap and ECU/FCU tenodesis) for the unstable distal ulnar stump and 3) the stability after the implantation of an ulnar head endoprosthesis following a Darrach resection on radioulnar convergence. With a dynamic PC-controled forearm simulator the rotation of 7 fresh-frozen cadaver upper extremities was actively and passively performed while loading relevant muscles. Resultant total forearm torque and the 3-dimensional kinematics of the ulna, radius and third metacarpal were recorded simultaneously. The implantation of the ulnar head endoprosthesis effectively restored the stability of the DRUJ. There were significantly better results after the implantation of the prosthesis compared with the Darrach and the soft tissue stabilization procedures. This study provides laboratory validity to the option of implanting an ulnar head endoprosthesis as an attempt to stabilize the distal forearm after Darrach resection in lieu of performing soft tissue stabilization techniques.

The dynamic radioulnar convergence of the Darrach procedure and the ulnar head hemiresection interposition arthroplasty: a biomechanical study.

Resection of the entire ulnar head (Darrach operation) and the hemiresection interposition arthroplasty are common methods of treating the arthritic distal radioulnar joint (DRUJ). Biomechnical investigation about both of these procedures is lacking. The purpose of this study was to evaluate the dynamic effects of both the hemiresection interposition arthroplasty and the Darrach procedure on radioulnar convergence and dorsal-palmar displacement and to compare their biomechanical behaviours. With a dynamic computer-controlled testing device, cadaveric forearm rotation was performed with simultaneous loading of relevant muscles. Torque along the forearm axis was generated by simulated muscle action through pneumoactuators attached to relevant tendons while the wrist was constrained to prescribed ranges of motion. The instability of the radius relative to the ulna was evaluated using displacement data of digitized landmarks in an ulnar coordinate system. Seven fresh-frozen cadaver upper extremities were used. The Darrach resection created an extreme instability of the forearm with movement of the radius ulnarly. Anteroposterior translations in each loading condition could also be detected, but the magnitude of displacement was small and less predictable. The results of the hemiresection interposition arthroplasty demonstrated significantly less instability compared with the Darrach results.

Second-generation cementless total hip arthroplasty. Eight to eleven-year results.

BACKGROUND: Second-generation cementless femoral components were designed to provide more reliable ingrowth and to limit distal osteolysis by incorporating circumferential proximal ingrowth surfaces. We examined the eight to eleven-year results of total hip arthroplasty with a cementless, anatomically designed femoral component and a cementless hemispheric acetabular component. METHODS: Ninety-two consecutive primary total hip arthroplasties with implantation of a femoral component with a circumferential proximal porous coating (Anatomic Hip) and a cementless hemispheric porous-coated acetabular component (Harris-Galante II) were performed in eighty-five patients. These patients were prospectively followed clinically and radiographically. Six patients (seven hips) died and five patients (seven hips) were lost to follow-up, leaving seventy-four patients (seventy-eight hips) who had been followed for a mean of ten years (range, eight to eleven years). The mean age at the time of the arthroplasty was fifty-two years. RESULTS: The mean preoperative Harris hip score of 51 points improved to 94 points at the time of final follow-up; 86% of the hips had a good or excellent result. Thigh pain was reported as mild to severe after seven hip arthroplasties. No femoral component was revised for any reason, and none were loose radiographically at the time of the last follow-up. Two hips underwent acetabular revision (one because of dislocation and one because of loosening). Kaplan-Meier survivorship analysis was performed with revision or loosening of any component as the end point. The ten-year survival rate was 96.4% +/- 2.1% for the total hip prosthesis, 100% for the femoral component, and 96.4% +/- 2.1% for the acetabular component. Radiolucencies adjacent to the nonporous portion of the femoral component were seen in sixty-eight (93%) of the -seventy-three hips with complete radiographic follow-up. Femoral osteolysis proximal to the lesser trochanter was noted in four hips (5%). No osteolysis was identified distal to the lesser trochanter. Periacetabular osteolysis was identified in twelve hips (16%). Five patients underwent exchange of the acetabular liner because of polyethylene wear. CONCLUSIONS: This second-generation cementless, anatomically designed femoral component provided excellent clinical and radiographic results with a 100% survival rate at ten years. The circumferential porous coating of this implant improved ingrowth and prevented distal osteolysis at a mean of ten years after the arthroplasty.

Rotational instability and malrotation after total knee arthroplasty.

Total knee arthroplasty has become the standard treatment for various disabling disorders of the knee and has proven long-term success. Surgical technique and prosthetic design have evolved to produce consistent and excellent results. Despite the current success of total knee arthroplasty, complications remain.

Problems with cementless total knee arthroplasty at 11 years followup.

One hundred two patients with 131 consecutive cementless total knee arthroplasties that retained the posterior cruciate ligament were followed up prospectively. The average age of the patients was 58 years (range, 32-75 years). The mean followup on the surviving knee arthroplasties was 11 years (range, 7-16 years). The patellar component was metal-backed in the first 112 (85%) knees, cementless all-polyethylene in the last 17 (13%) knees, and two knees had a prior patellectomy. Forty-four metal-backed patellar components (48%) were revised; nine were loose, and 35 had polyethylene wear through. Thirteen femoral components (12%) were revised because of femoral abrasion from a failed metal-backed patellar component. No other femoral component was revised, loose, or had osteolysis develop. Nine (8%) tibial components had failure of ingrowth; eight have been revised. Partial radiolucencies occurred in 53% of the tibias. Thirteen (12%) small osteolytic lesions developed, all around screws or screw holes in the tibial components. At an average of 11 years followup, cementless fixation yielded mixed results: cementless femoral fixation was excellent and metal-backed patellar components had a 48% patellar revision rate. Cementless tibial components had an 8% aseptic loosening rate and a 12% incidence of small osteolytic lesions. Based on these results, the authors have abandoned cementless fixation in total knee arthroplasty.

Gout-induced arthropathy after total knee arthroplasty: a report of two cases.

Gout, although relatively rare in joint replacements, can present as an acute or chronic painful knee or hip arthroplasty. Gout and acute infection of a joint replacement can be difficult to differentiate, with the physical examination and laboratory study results frequently being similar. Both conditions can present with a rapid onset of joint pain, swelling, erythema, and constitutional symptoms, including fevers and malaise. Laboratory findings in both conditions often include an elevated leukocyte count, erythrocyte sedimentation rate, and C-reactive protein level. Negatively birefringent, needle-shaped crystals in the synovial fluid confirm the diagnosis of gout. The mistaken diagnosis of septic arthritis in a joint replacement with crystal-induced synovitis can lead to inappropriate open debridement or component removal. The current study includes a review of the literature and presents two cases of gout after total knee arthroplasty. These cases suggest that in situations of suspected sepsis without synovial fluid crystals, operative intervention is indicated with a presumed diagnosis of septic arthritis. The identification of chalky white or yellow deposits in the synovium or bone is highly suggestive of gout. The definitive diagnosis is made by polarized light histologic evaluation of these tissues. If these deposits are present in the absence of a positive preoperative culture, positive Gram stain for bacteria, or component loosening, component retention is indicated.

Optimizing femoral component rotation in total knee arthroplasty.

Femoral component rotation is important in total knee arthroplasty to optimize patellofemoral and tibiofemoral kinematics. More recently, the epicondylar axis has been cited as the definitive landmark for femoral component rotation. However, there are few studies to support the validity of this rotational landmark and its effect on the patellofemoral and tibiofemoral articulations. In the current study, a total knee arthroplasty was done in 11 knees from cadavers. The knees were tested with various femoral component rotations from 5 degrees internal rotation to 5 degrees external rotation referenced to the epicondylar axis and to the posterior femoral condyles. Each knee acted as its own internal control. The knees were actively ranged from 0 degrees to 100 degrees by a force on the quadriceps tendon in an Oxford knee simulator. Three-dimensional kinematics of all three components were measured whereas a multiaxial transducer imbedded in the patella measured patellofemoral forces. Femoral component rotation parallel to the epicondylar axis resulted in the most normal patellar tracking and minimized patellofemoral shear forces early in flexion. This optimal rotation also minimized tibiofemoral wear motions. These beneficial effects of femoral rotation were less reproducibly related to the posterior condyles. Rotating the femoral component either internal or external to the epicondylar axis worsened knee function by increasing tibiofemoral wear motion and significantly worsening patellar tracking with increased shear forces early in flexion. Based on the current study, the femoral component should be rotationally aligned parallel to the epicondylar axis to avoid patellofemoral and tibiofemoral complications.

Treatment of isolated injuries of the lunotriquetral ligament. A comparison of arthrodesis, ligament reconstruction and ligament repair.

We studied 57 patients with isolated lunotriquetral injuries treated by arthrodesis, direct ligament repair, or ligament reconstruction. The outcomes were compared by using written questionnaires, the Disabilities of the Arm, Shoulder and Hand (DASH) score, range of movement, strength, morbidity and rates of reoperation. Isolated lunotriquetral injury was confirmed by arthroscopy or arthrotomy. The mean age of the patients was 30.7 years (15.4 to 53.7) and the injuries were subacute or chronic in 98.2%. Eight patients underwent lunotriquetral reconstruction using a distally-based strip of the tendon of extensor carpi ulnaris, 27 had lunotriquetral repair and 22 had lunotriquetral arthrodesis. The mean follow-up was 9.5 years (2 to 22). The probability of remaining free from complications at five years was 68.6% for reconstruction, 13.5% for repair, and less than 1% for arthrodesis. Of the lunotriquetral arthrodeses, 40.9% developed nonunion and 22.7% developed ulnocarpal impaction. The probability of not requiring further surgery at five years was 68.6% for reconstruction, 23.3% for repair and 21.8% for arthrodesis. The DASH scores for each group were not significantly different. Objective improvements in strength and movement, subjective indicators of pain relief and satisfaction were significantly higher in the lunotriquetral repair and reconstruction groups than in those undergoing arthrodesis.

Posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis.

BACKGROUND: Although initial reports on posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis have been encouraging, a high rate of late instability necessitating revision has been reported recently. The purpose of the present prospective study was to analyze the results of posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis. METHODS: Seventy-two posterior cruciate ligament-retaining total knee arthroplasties in fifty-one patients with rheumatoid arthritis were studied prospectively. All procedures were performed with the Miller-Galante I prosthesis. Eighteen patients (twenty-four knees) died before the eight-year follow-up and one patient (two knees) was lost to follow-up, leaving forty-six knees (thirty-two patients) for review. These forty-six knees were evaluated clinically (with particular attention to posterior instability) and radiographically at annual intervals for a mean of 10.5 years (range, eight to fourteen years). RESULTS: Forty-four (95%) of forty-six knees had a good or excellent result at a mean of 10.5 years. However, nine (13%) of the original seventy-two knees had revision of the implant, with six of the revisions performed because of failure of a metal-backed patellar component. The rate of survival at ten years was 93% 4% with femoral or tibial revision for any reason as the end point and 81% 5% with any reoperation as the end point. There was no aseptic loosening in any knee. Posterior instability was identified clinically and/or radiographically in two (2.8%) of the original seventy-two knees; both unstable knees were in the same patient. CONCLUSION: Posterior cruciate ligament-retaining total knee arthroplasty yielded satisfactory clinical and radiographic results in patients with rheumatoid arthritis at intermediate-term follow-up (mean, 10.5 years). Therefore, we believe that it remains an excellent treatment option for these patients.

The effect of component placement on knee kinetics after arthroplasty with an unconstrained prosthesis.

The mechanical success of a total knee replacement demands stable patellar tracking without subluxation and, stable tracking, in turn, can depend largely on the medial-lateral forces restraining the patella. Patellar button medialization has been advocated as a means of reducing subluxation, and experimental evidence has shown femoral component rotation also affects medial-lateral forces. Surgeons have choices in femoral component rotation and patellar button medialization and must frequently make intra-operative decisions concerning component placement because of anatomical variations among patients. Thus, in seeking to minimize medial-lateral patellar force, we examined the effects of patellar button medialization and external femoral component rotation. The study used an unconstrained total knee system implanted in nine cadaveric specimens tested on a knee simulator operating through flexion angles up to 100 degrees. Tests included all combinations of external femoral component rotation of 0 degree, 2.5 degrees, and 5 degrees and patellar placement at the geometric center and at 3.75 mm medial to the geometric center. A video-based motion analysis system tracked patellar and tibial kinematics while a six-component load cell measured patellofemoral loads. Repeated measures analysis of variance revealed a statistically significant decrease in the average medial-lateral force with button medialization but no significant change with femoral component rotation. Neither femoral component rotation nor patellar button medialization had an effect on the normal component of the patellar reaction force. External femoral component rotation did cause significant increases in lateral patellar tilt, in tibial varus angle, and in external tibial rotation. Button medialization caused significant increases in lateral patellar tracking, lateral patellar tilt and external tibial rotation. The results in medial-lateral patellar forces quantify the benefit of patellar button medialization and discount any benefit of femoral rotation. The change in tibial kinematics with patellar button medialization and femoral component rotation cannot be measured in vivo with current technology, and the precise clinical implications are unknown.

Functional ligamentous anatomy of the trapezium and trapeziometacarpal joint (gross and arthroscopic).

A detailed description of the ligamentous anatomy of the thumb basal joint is presented from a gross, arthroscopic, and functional point of view. All 16 ligaments that stabilize the trapezium and trapeziometacarpal (TM) joint are discussed in association with their presumed functional relevance regarding trapezial and trapeziometacarpal joint stability. Geometric and mathematical models are introduced to help describe and support anatomic observations with regard to ligament function. The dorsoradial ligament appears to be an important stabilizer of the TM joint against dorsally directed forces. The trapeziotrapezoid, trapezio-II metacarpal, and trapezio-III metacarpal ligaments appear to function as tension bands to help support the trapezium against cantilever bending forces imparted onto the trapezium by the thumb metacarpal.

Long-term followup of the Miller-Galante total knee replacement.

One hundred seventy-two consecutive cemented Miller-Galante-I total knee arthroplasties in 155 patients were compared with 109 consecutive cemented Miller-Galante-II total knee arthroplasties in 92 patients. The average followup was 11 years (range, 8-15 years) and 9 years (range, 8-10 years), respectively. Of the 172 Miller-Galante-I arthroplasties, there have been 21 revisions; 15 patellar revisions; two included femoral revisions attributable to abrasion. Six additional well-fixed femoral and tibial components were revised: two for early instability, one for pain, one for periprosthetic fracture, and two for infection. No component had aseptic loosening or osteolysis. Using revision or loosening of any components as the end point, the Kaplan-Meier 10-year survivorship was 84.1% +/- 4.1%. Of the 109 Miller-Galante-II arthroplasties, there have been no component revisions, no aseptic loosening, and no osteolysis. Using revision or loosening of any components as the end point, the Kaplan-Meier 10-year survivorship was 100%. The Miller-Galante knee systems showed excellent fixation with no loosening and no osteolysis at as many as 15 years. Additionally, there have been no component revisions for late instability at as many as 15 years. Finally, the high prevalence of patellofemoral complications with the Miller-Galante-I design has been obviated with the Miller-Galante-II design.

Cementless acetabular reconstruction after acetabular fracture.

BACKGROUND: Total hip arthroplasty in patients with posttraumatic arthritis has produced results inferior to those in patients with nontraumatic arthritis. The use of cementless acetabular reconstruction, however, has not been extensively studied in this clinical context. Our purpose was to compare the intermediate-term results of total hip arthroplasty with a cementless acetabular component in patients with posttraumatic arthritis with those of the same procedure in patients with nontraumatic arthritis. We also compared the results of arthroplasty in patients who had had prior operative treatment of their acetabular fracture with those in patients who had had prior closed treatment of their acetabular fracture. METHODS: Thirty total hip arthroplasties were performed with use of a cementless hemispheric, fiber-metal-mesh-coated acetabular component for the treatment of posttraumatic osteoarthritis after acetabular fracture. The median interval between the fracture and the arthroplasty was thirty-seven months (range, eight to 444 months). The average age at the time of the arthroplasty was fifty-one years (range, twenty-six to eighty-six years), and the average duration of follow-up was sixty-three months (range, twenty-four to 140 months). Fifteen patients had had prior open reduction and internal fixation of their acetabular fracture (open-reduction group), and fifteen patients had had closed treatment of the acetabular fracture (closed-treatment group). The results of these thirty hip reconstructions were compared with the intermediate-term results of 204 consecutive primary total hip arthroplasties with cementless acetabular reconstruction in patients with nontraumatic arthritis. RESULTS: Operative time (p < 0.001), blood loss (p < 0.001), and perioperative transfusion requirements (p < 0.001) were greater in the patients with posttraumatic arthritis than they were in the patients with nontraumatic arthritis. Of the patients with posttraumatic arthritis, those who had had open reduction and internal fixation of their acetabular fracture had a significantly longer index procedure (p = 0.01), greater blood loss (p = 0.008), and a higher transfusion requirement (p = 0.049) than those in whom the fracture had been treated by closed methods. Eight of the fifteen patients with a previous open reduction and internal fixation required an elevated acetabular liner compared with one of the fifteen patients who had been treated by closed means (p = 0.005). Two of the fifteen patients with a previous open reduction and internal fixation required bone-grafting of acetabular defects compared with seven of the fifteen patients treated by closed means (p = 0.04). The thirty patients treated for posttraumatic arthritis had an average preoperative Harris hip score of 41 points, which increased to 88 points at the time of follow-up; there was no significant difference between the open-reduction and closed-treatment groups (p = 0.39). Twenty-seven patients (90%) had a good or excellent result. There were no dislocations or deep infections. The Kaplan-Meier ten-year survival rate, with revision or radiographic loosening as the end point, was 97%. These results were similar to those of the patients who underwent primary total hip arthroplasty for nontraumatic arthritis. CONCLUSIONS: The intermediate-term clinical results of total hip arthroplasty with cementless acetabular reconstruction for posttraumatic osteoarthritis after acetabular fracture were similar to those after the same procedure for nontraumatic arthritis, regardless of whether the acetabular fracture had been internally fixed initially. However, total hip arthroplasty after acetabular fracture was a longer procedure with greater blood loss, especially in patients with previous open reduction and internal fixation. Previous open reduction and internal fixation predisposed the hip to more intraoperative instability but less bone deficiency.

Vascularized orthotopic osteochondral transplantation of the canine proximal femur.

Osteochondral vascularized proximal femoral allografts were orthotopically transplanted in five adult beagles (four experimental and one control). The experimental animals were placed on 0.1 mg/kg of FK506 intravenously for 7 days, and then converted to 1.0 mg/kg orally. Biopsies of the femoral heads were taken at 3 weeks postoperatively and at 1-month intervals thereafter. The specimens were studied histologically with a hemotoxylin and eosin staining technique. Bone biopsies showed no microscopic evidence of rejection, and only minimal evidence of necrosis. Patency of the microvascular anastomosis was confirmed with bone scanning, using technitium 99m phosphate, arteriograms, and by Doppler flowmeter. All animals had an uneventful postoperative course, with achievement of full weight-bearing status by postoperative day 10, and normal activity by 1 month postoperatively. There were no infections or hip dislocations. One animal sustained a femoral neck fracture and was sacrificed at 4 months. At 6 months, the remaining animals were sacrificed. At necropsy, the experimental animals and the normal dog showed viable chondrocytes and osteocytes, with minimal bone necrosis. No dislocations or allograft rejections were observed. Based on this small series, a successful technique has been developed for orthotopic transplantation of a vascularized hip joint in a canine model.

The anatomy of the ligaments of the wrist and distal radioulnar joints.

The ligaments of the wrist are responsible for guiding and constraining the complex motion of the carpal bones relative to the forearm bones, the metacarpals, and contiguous carpal bones. The majority of wrist ligaments are found within the joint capsule as organized thickenings composed of parallel collagen fascicles, small caliber nerves and blood vessels, and lined on their deep surfaces by synoviocytes. The palmar radiocarpal ligament complex is composed of the radioscaphocapitate, long radiolunate, radioscapholunate and short radiolunate ligaments. The ulnocarpal ligaments include the ulnolunate, ulnotriquetral and ulnocapitate ligaments. Dorsally, the radiocarpal joint is spanned by the dorsal radiocarpal ligament. Palmar ligaments connecting the proximal and distal carpal rows include the scaphotrapeziotrapezoid, scaphocapitate, triquetrocapitate and triquetrohamate ligaments. Within each row are interosseous ligaments connecting adjacent carpal bones, each divisible into dorsal and palmar components. There are unique regions within some of the ligaments, such as a zone of fibrocartilage in the proximal regions of the scapholunate and lunotriquetral interosseous ligaments, and strong deep regions connecting the trapezoid, capitate, and hamate. The distal radioulnar joint is connected by the triangular fibrocartilage complex, composed of a fibrocartilaginous disc and the palmar and dorsal radioulnar ligaments. The ulnocarpal ligaments attach to the palmar radioulnar ligament rather than directly to the ulna, allowing increased independence between wrist and forearm motion.