Peter Tang

Chondroblastoma of Bone

Background: Chondroblastoma of bone is a rare lesion, and few large series have been reported. The purpose of this paper is to report forty-seven cases treated by one group of surgeons and to identify factors associated with more aggressive tumor behavior. Methods: Seventy-three patients with chondroblastoma of bone were treated between 1977 and 1998. We were able to obtain historical data, imaging studies, histological findings, and adequate personal or telephone follow-up to determine the outcome for forty-seven patients. Results: The lesions were distributed widely in the skeleton, but most were in the epiphyses or apophyses of the long bones, especially the proximal part of the tibia (eleven tumors) and the proximal part of the humerus (ten tumors). The principal presenting symptoms were pain and limitation of movement. The treatment consisted of a variety of procedures, but the majority of the patients had intralesional curettage and packing with allograft or autograft bone chips or polymethylmethacrylate. Most of the patients had an excellent functional result, although in three osteoarthritis developed in the adjacent joint. Seven patients (15 percent) had a local recurrence; three of them had a second recurrence and one, a third recurrence. One patient died of widespread metastases, and another who had metastases to multiple sites was alive and disease-free after aggressive treatment of the metastatic lesions. Conclusions: While the size of the lesion, the age and gender of the patient, the status of the growth plate, and an aneurysmal-bone-cyst component to the tumor had no significant effect on the recurrence rate, lesions around the hip (the proximal part of the femur, the greater trochanter, and the pelvis) accounted for the majority (five) of the seven recurrent tumors and one of the two metastatic lesions.

Surgical treatment of hemangiomas of soft tissue.

Hemangioma is one of the most common soft tissue tumors comprising 7% of all benign tumors. The etiology is unclear. Many treatment modalities for the symptomatic deep subdermal or intramuscular hemangioma have been used, but surgical excision is the preferred treatment. During the past 20 years, 89 patients with soft tissue hemangiomas were treated by surgical excision at the authors’ institution. This study was done to define the clinical characteristics of pathologically proven hemangiomas and to evaluate the outcome of the operative procedures. Intralesional or marginal excision for symptomatic hemangiomas yields satisfactory results for pain relief, functional recovery, and avoidance of recurrence. According to the data a hemangioma of the soft tissues is a benign lesion in which more aggressive surgery (wide or radical excision) or other modalities such as radiation usually are not warranted.

Fatal laryngeal obstruction by iatrogenic subglottic cyst

Prolonged nasotracheal intubation in a 3 1/2-month-old premature infant produced obliteration of the laryngeal ventricle and scarring of vocal cord musculature, and also resulted in the development of subglottic retention cysts, one large enough to cause fatal laryngeal obstruction.

Histologic and functional outcomes of nerve defects treated with acellular allograft versus cabled autograft in a rat model.

Acellular nerve allograft is a new option for bridging nerve defects that allows appropriate diameter matching. The aim of the study was to compare the histologic and functional recovery of nerve defects treated with acellular nerve allograft versus cabled sural nerve autograft.

Effect of white adipose tissue flap and insulin‐like growth factor‐1 on nerve regeneration in rats

Adipose tissue‐derived stem cells and insulin‐like growth factor‐1 (IGF‐1) have shown potential to enhance peripheral nerve regeneration. The purpose of this study was to investigate the effect of an in vivo biologic scaffold, consisting of white adipose tissue flap (WATF) and/or IGF‐1 on nerve regeneration in a crush injury model. Forty rats all underwent a sciatic nerve crush injury and then received: a pedicled WATF, a controlled local release of IGF‐1, both treatments, or no treatment at the injury site. Outcomes were the normalized maximum isometric tetanic force (ITF) of the tibialis anterior muscle and histomorphometric measurements. At 4 weeks, groups with WATF had a statistically significant improvement in maximum ITF recovery, as compared to those without (P < 0.05), and there was an increase in myelin thickness and total axon count in the WATF‐only group versus control (P < 0.01). Functional and histomorphometric data suggest that IGF‐1 suppressed the effect of the WATF. Use of a pedicled WATF improved the functional and histomorphometrical results after axonotmesis in a rat model. IGF‐1 does not appear to enhance nerve regeneration in this model. Utilizing the WATF may have a beneficial therapeutic role in peripheral nerve injuries.

Aggravation of inflammatory response by costimulation with titanium particles and mechanical perturbations in osteoblast- and macrophage-like cells

The interface between bone tissue and metal implants undergoes various types of mechanical loading, such as strain, compression, fluid pressure, and shear stress, from daily activities. Such mechanical perturbations create suboptimal environments at the host bone-implant junction, causing an accumulation of wear particles and debilitating osseous integration, potentially leading to implant failure. While many studies have focused on the effect of particles on macrophages or osteoprogenitor cells, differential and combined effects of mechanical perturbations and particles on such cell types have not been extensively studied. In this study, macrophages and osteoprogenitor cells were subjected to physiological and superphysiological mechanical stimuli in the presence and absence of Ti particles with the aim of simulating various microenvironments of the host bone-implant junction. Macrophages and osteoprogenitor cells were capable of engulfing Ti particles through actin remodeling and also exhibited changes in mRNA levels of proinflammatory cytokines under certain conditions. In osteoprogenitor cells, superphysiological strain increased proinflammatory gene expression; in macrophages, such mechanical perturbations did not affect gene expression. We confirmed that this phenomenon in osteoprogenitor cells occurred via activation of the ERK1/2 signaling pathway as a result of damage to the cytoplasmic membrane. Furthermore, AZD6244, a clinically relevant inhibitor of the ERK1/2 pathway, mitigated particle-induced inflammatory gene expression in osteoprogenitor cells and macrophages. This study provides evidence of more inflammatory responses under mechanical strains in osteoprogenitor cells than macrophages. Phagocytosis of particles and mechanical perturbation costimulate the ERK1/2 pathway, leading to expression of proinflammatory genes.

Scaphoid Excision and 4-Bone Arthrodesis Versus Proximal Row Carpectomy: A Comparison of Contact Biomechanics

PURPOSE We compare scaphoid excision and 4-bone arthrodesis (FBA) with proximal row carpectomy (PRC) in terms of contact pressure, area, and location. METHODS Six cadaveric forearms underwent simulated FBA with K-wires. We measured pressures in the radiocarpal joint with Fuji contact film after we applied a 200-N load via the wrist tendons with the wrist in neutral, flexion, and extension. We repeated the experiment after excising the lunate and triquetrum, to create a PRC in the same specimens. RESULTS Contact pressure in the PRC wrist was significantly greater, by 25%, compared with the FBA wrist for all wrist positions. The PRC wrist had a significantly smaller contact area, by 43%, compared with the FBA wrist. In the FBA wrist, lunate contact was more dorsal in flexion but more volar in extension. In the PRC wrist, capitate contact was more dorsal and radial in flexion, whereas the contact was more volar and ulnar in extension. Comparing contact location, FBA contact was significantly more ulnar than PRC contact in wrist flexion. We found no significant difference in contact translation (the distance between the contact locations in the positions of wrist flexion and extension) for the lunate in FBA or the capitate in PRC. CONCLUSIONS The FBA wrist has significantly lower contact pressure (P < .001), greater contact area (P < .001), and equal contact translation compared with the PRC wrist. These qualities may make FBA less susceptible to degeneration over time. By advancing our understanding of the biomechanics of both wrist procedures, we may better tailor them to the individual patient. CLINICAL RELEVANCE Current biomechanical evidence is lacking for common motion-preserving procedures for wrist arthritis. Comparing contact pressure, area, and location provides a biomechanical basis of our clinical understanding of these surgeries.

Osteochondral resurfacing with proximal row carpectomy: 8-year follow-up.

Degenerative arthrosis of the proximal row remains a challenging problem for both patients and surgeons. Proximal row carpectomy is a motion-preserving treatment option, with studies documenting acceptable long-term outcomes. Proximal row carpectomy is an attractive option because there is no need for fusion to occur between the carpal bones, as in 4-corner fusion. As a result, laborers and smokers may be able to return to work more quickly. However, capitate chondrosis traditionally has been considered a contraindication to proximal row carpectomy. The goal of this study was to review the long-term follow-up of patients who underwent osteochondral resurfacing of capitate chondrosis performed in the same setting as proximal row carpectomy. Final follow-up was obtained in 5 of 8 (63%) patients at an average of 101 months (range, 99-102) after surgery. Grip strength improved at each time point, but wrist flexion and extension decreased. The average Mayo Wrist Score was 74 (range, 65-85) and remained stable or improved in all patients between the 18-month visit and the final visit. The Disabilities of the Arm, Shoulder and Hand (DASH) score was unchanged at final follow-up compared with 18-month follow-up (P=.7). This study found that osteochondral resurfacing of the capitate in the setting of proximal row carpectomy for patients with capitate chondrosis offers good outcomes compared with standard proximal row carpectomy in patients without capitate chondrosis on patient-directed outcome tools (DASH, Mayo Wrist Score) at long-term follow-up of 101 months.

Local Recurrence of Chondroblastoma

To The Editor: We thoroughly enjoyed reading the article, “Chondroblastoma of Bone” (82-A: 1140-5, Aug. 2000), by Ramappa et al. Coincidentally, we have reviewed our own experience with this subject and have found that nine (13%) of our sixty-nine patients had a local recurrence, a figure nearly identical to that from the Boston study. We were unable to identify any risk factors for local recurrence, although two of eight patients with proximal femoral lesions had a local recurrence. The only other frequent sites of recurrence were the proximal part of the humerus (two of sixteen) and the proximal part of the tibia (two of thirteen). We have used curettage alone without bone graft or cement in the vast majority of patients and have been quite happy with the results. It was not clear from the Ramappa paper whether bone cement …

Effect of Capitate Morphology on Contact Biomechanics After Proximal Row Carpectomy

PURPOSE Proximal row carpectomy (PRC) is used as a treatment for a variety of wrist pathologies to maintain motion and to improve strength and decrease pain. Several studies have looked at how PRC alters wrist characteristics, although they did not provide an explanation for the variability observed in outcomes. Studies have classified the capitate into 3 unique types: round, V-shaped, or flat. We hypothesized that these differences in morphology could affect the contact biomechanics between the radius and the capitate after PRC. METHODS A total of 14 cadaveric wrists underwent PRC. They were classified by capitate morphology and then loaded to 200 N in a neutral position, flexion, and extension. We measured contact area, contact pressure, and location using pressure-sensitive film in all 3 positions and compared their morphology types. RESULTS Nine wrists had a round-type capitate, 4 had a V-shaped capitate, and 1 had a flat capitate, which we excluded from statistical analysis. Comparing round and V-shaped types, we found no differences in contact area, pressure, or location in any wrist position For the V-shaped capitates, there was increased contact pressure in flexion and extension compared with the wrist in neutral. Center of pressure translated dorsal and radial in flexion to volar and ulnar in extension for all types. CONCLUSIONS When we compared V-shaped and round-type capitates, we found no significant differences in contact characteristics of the wrist after PRC. There were some differences in contact pressure for V-shaped capitates in various wrist positions. CLINICAL RELEVANCE Differences between round and V-shaped capitates do not appear to affect contact biomechanics after PRC. Thus, these 2 capitate shapes may not necessarily be a factor in the decision-making process to perform PRC.